S.M.H. was supported by postdoctoral fellowships from the Canadian Institutes for Health Research (CIHR), Heart &#38; Stroke Foundation of Canada (HSFC) and Alberta Innovates Health Solutions (AiHS); J.E.H. is supported by a grant from the National Heart, Lung and Blood Institute PO1HL-51971.

<ol>
	<li>Young, C. N., Davisson, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+assessment+of+neurocardiovascular+regulation+in+the+mouse:+principles,+progress,+and+prospects.">In vivo assessment of neurocardiovascular regulation in the mouse: principles, progress, and prospects.</a> Am J Physiol Heart Circ Physiol. 301 (3), H654-H662 (2011).</li><li>Kass, D. A., Hare, J. M., Georgakopoulos, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+cardiac+function:+a+cautionary+tail.">Murine cardiac function: a cautionary tail.</a> Circ Res. 82 (4), 519-522 (1998).</li><li>Charkoudian, N., Wallin, B. 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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+recording+of+renal+sympathetic+nerve+activity+in+unrestrained,+conscious+mice.">Direct recording of renal sympathetic nerve activity in unrestrained, conscious mice.</a> Hypertension. 60 (3), 856-864 (2012).</li><li>DeBeck, L. D., Petersen, S. R., Jones, K. E., Stickland, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+rate+variability+and+muscle+sympathetic+nerve+activity+response+to+acute+stress:+the+effect+of+breathing.">Heart rate variability and muscle sympathetic nerve activity response to acute stress: the effect of breathing.</a> Am J Physiol Regul Integr Comp Physiol. 299 (1), R80-R91 (2010).</li><li>Krowicki, Z. K., Kapusta, D. 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A., Azar, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+continuous+chronic+measurement+and+recording+of+blood+pressure,+heart+rate+and+activity+in+the+rat+via+radio-telemetry.">A new method for continuous chronic measurement and recording of blood pressure, heart rate and activity in the rat via radio-telemetry.</a> Clin Exp Hypertens A. 13 (5), 885-895 (1991).</li><li>Tallam, L. S., Silva, d. a., A, A., Hall, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Melanocortin-4+receptor+mediates+chronic+cardiovascular+and+metabolic+actions+of+leptin.">Melanocortin-4 receptor mediates chronic cardiovascular and metabolic actions of leptin.</a> Hypertension. 48 (1), 58-64 (2006).</li><li>Van Vliet, B. N., Chafe, L. L., Antic, V., Schnyder-Candrian, S., Montani, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+and+indirect+methods+used+to+study+arterial+blood+pressure.">Direct and indirect methods used to study arterial blood pressure.</a> J Pharmacol Toxicol Methods. 44 (2), 361-373 (2000).</li><li>Zvara, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+non-anesthetized+mouse+model+for+recording+sensory+urinary+bladder+activity.">A non-anesthetized mouse model for recording sensory urinary bladder activity.</a> Front Neurol. 1, 127 (2010).</li><li>Hagan, K. P., Bell, L. B., Mittelstadt, S. W., Clifford, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+dynamic+exercise+on+renal+sympathetic+nerve+activity+in+conscious+rabbits.">Effect of dynamic exercise on renal sympathetic nerve activity in conscious rabbits.</a> J Appl Physiol. 74 (5), 2099-2104 (1985).</li><li>Matsukawa, K., Ninomiya, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+renal+sympathetic+nerve+activity,+heart+rate+and+arterial+blood+pressure+associated+with+eating+in+cats.">Changes in renal sympathetic nerve activity, heart rate and arterial blood pressure associated with eating in cats.</a> J Physiol. 390, 229-242 (1987).</li><li>Stocker, S. D., Muntzel, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recording+sympathetic+nerve+activity+chronically+in+rats:+surgery+techniques,+assessment+of+nerve+activity,+and+quantification.">Recording sympathetic nerve activity chronically in rats: surgery techniques, assessment of nerve activity, and quantification.</a> Am J Physiol Heart Circ Physiol. 305 (10), 6 (2013).</li><li>Burke, S. L., Lambert, E., Head, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+approaches+to+quantifying+sympathetic+nerve+activity.">New approaches to quantifying sympathetic nerve activity.</a> Curr Hypertens Rep. 13 (3), 249-257 (2011).</li><li>Smith, F. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Techniques+for+recording+renal+sympathetic+nerve+activity+in+awake,+freely+moving+animals.">Techniques for recording renal sympathetic nerve activity in awake, freely moving animals.</a> Methods. 30 (2), 122-126 (2003).</li><li>Miki, K., Kosho, A., Hayashida, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+continuous+measurements+of+renal+sympathetic+nerve+activity+and+cardiovascular+function+during+exercise+in+rats.">Method for continuous measurements of renal sympathetic nerve activity and cardiovascular function during exercise in rats.</a> Exp Physiol. 87 (1), 33-39 (2002).</li><li>Yoshimoto, M., Miki, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+renal+sympathetic+nerve+activity+in+freely+moving+mice.">Measurement of renal sympathetic nerve activity in freely moving mice.</a> J Physiol. 560, (2004).</li><li>Yoshimoto, M., Miki, K., Fink, G. D., King, A., Osborn, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+angiotensin+II+infusion+causes+differential+responses+in+regional+sympathetic+nerve+activity+in+rats.">Chronic angiotensin II infusion causes differential responses in regional sympathetic nerve activity in rats.</a> Hypertension. 55 (3), 644-651 (2010).</li><li>Salman, I. M., Sarma Kandukuri, ., Harrison, D., L, J., Hildreth, C. M., Phillips, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+conscious+telemetry+recordings+demonstrate+increased+renal+sympathetic+nerve+activity+in+rats+with+chronic+kidney+disease.">Direct conscious telemetry recordings demonstrate increased renal sympathetic nerve activity in rats with chronic kidney disease.</a> Front Physiol. 6, 218 (2015).</li><li>Morgan, D. A., Despas, F., Rahmouni, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+leptin+on+sympathetic+nerve+activity+in+conscious+mice.">Effects of leptin on sympathetic nerve activity in conscious mice.</a> Physiol Rep. 3 (9), (2015).</li><li>Alfie, M. E., Sigmon, D. H., Pomposiello, S. I., Carretero, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+high+salt+intake+in+mutant+mice+lacking+bradykinin-B2+receptors.">Effect of high salt intake in mutant mice lacking bradykinin-B2 receptors.</a> Hypertension. 29 (1 Pt 2), 483-487 (1997).</li><li>Dietz, J. R., Landon, C. S., Nazian, S. J., Vesely, D. L., Gower, W. 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A., Zuurbier, C. J., Ince, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+ventilation+of+mice.">Mechanical ventilation of mice.</a> Basic Res Cardiol. 95 (6), 510-520 (2000).</li><li>Zuurbier, C. J., Emons, V. M., Ince, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodynamics+of+anesthetized+ventilated+mouse+models:+aspects+of+anesthetics,+fluid+support,+and+strain.">Hemodynamics of anesthetized ventilated mouse models: aspects of anesthetics, fluid support, and strain.</a> Am J Physiol Heart Circ Physiol. 282 (6), H2099-H2105 (2002).</li><li>Farnham, M. M., O'Connor, E. T., Wilson, R. J., Pilowsky, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+preparation+of+mice+for+recording+cardiorespiratory+parameters+in+vivo.">Surgical preparation of mice for recording cardiorespiratory parameters in vivo.</a> J Neurosci Methods. 248, 41-45 (2015).</li><li>Cuellar, J. M., Antognini, J. F., Carstens, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+in+vivo+method+for+recording+single+unit+activity+in+lumbar+spinal+cord+in+mice+anesthetized+with+a+volatile+anesthetic.">An in vivo method for recording single unit activity in lumbar spinal cord in mice anesthetized with a volatile anesthetic.</a> Brain Res Brain Res Protoc. 13 (2), 126-134 (2004).</li><li>Carruba, M. O., Bondiolotti, G., Picotti, G. B., Catteruccia, N., Da Prada, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+diethyl+ether,+halothane,+ketamine+and+urethane+on+sympathetic+activity+in+the+rat.">Effects of diethyl ether, halothane, ketamine and urethane on sympathetic activity in the rat.</a> Eur J Pharmacol. 134 (1), 15-24 (1987).</li><li>Wang, G. F., Mao, X. J., Chen, Z. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urethane+suppresses+renal+sympathetic+nerve+activity+in+Wistar+rats.">Urethane suppresses renal sympathetic nerve activity in Wistar rats.</a> Eur Rev Med Pharmacol Sci. 18 (10), 1454-1457 (2014).</li><li>Xu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+induced+hypothermia+on+renal+sympathetic+nerve+activity+and+baroreceptor+reflex+in+urethane-anesthetized+rabbits.">Effects of induced hypothermia on renal sympathetic nerve activity and baroreceptor reflex in urethane-anesthetized rabbits.</a> Crit Care Med. 28 (12), 3854-3860 (2000).</li><li>Shimokawa, A., Kunitake, T., Takasaki, M., Kannan, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+effects+of+anesthetics+on+sympathetic+nerve+activity+and+arterial+baroreceptor+reflex+in+chronically+instrumented+rats.">Differential effects of anesthetics on sympathetic nerve activity and arterial baroreceptor reflex in chronically instrumented rats.</a> J Auton Nerv Syst. 72 (1), 46-54 (1998).</li><li>Janssen, B. J., Smits, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+control+of+blood+pressure+in+mice:+basic+physiology+and+effects+of+genetic+modification.">Autonomic control of blood pressure in mice: basic physiology and effects of genetic modification.</a> Am J Physiol Regul Integr Comp Physiol. 282 (6), R1545-R1564 (2002).</li><li>Nunn, N., Feetham, C. H., Martin, J., Barrett-Jolley, R., Plagge, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elevated+blood+pressure,+heart+rate+and+body+temperature+in+mice+lacking+the+XLalphas+protein+of+the+Gnas+locus+is+due+to+increased+sympathetic+tone.">Elevated blood pressure, heart rate and body temperature in mice lacking the XLalphas protein of the Gnas locus is due to increased sympathetic tone.</a> Exp Physiol. 98 (10), 1432-1445 (2013).</li></ol>

The authors have nothing to disclose.

Herein we have outlined, demonstrated and validated a novel method for targeted evaluation of RSNA in conscious mice, free to move and rest comfortably in their home cages. Following surgical implantation of an arterial pressure radiotelemeter, an indwelling intravenous infusion catheter and a custom-designed bipolar RSNA electrode, mice recovered from surgery and were left undisturbed for 48 to 72 hours. Mice remained comfortably settled in their home cage at all times (including experimental periods) with unrestricted ...

Interest in using mice in several areas of biomedical research continues to expand with the development of countless genetically engineered models. For the most part, technical advances have kept pace with the increased use of mice in physiology and there is now an impressive selection of miniaturized devices developed specifically for measuring important physiological parameters in mice. Although telemetric devices for direct measurement of autonomic nervous tone in the conscious rat have been available for over a decade, miniaturized devices for assessing nerve activity in conscious mice are currently not available. Investigators typically circumvent this limitation by evaluating the contribution of the autonomic nervous system with indirect methods (i.e. plasma or urine catecholamines, pharmacological autonomic blockade, spectral analysis of patterns of blood pressure/heart rate)1.
While these approaches provide valuable information, the result is a global picture of overall autonomic tone, rather than revealing the discrete contribution of isolated populations of nerves to the phenomenon under investigation. Alternatively, direct recording of activity from specific nerves has been executed in anesthetized mice, which poses a multitude of concerns. It is exceedingly difficult to maintain stable blood pressure within the physiological range in an anesthetized mouse for several hours following surgery. In fact, in these types of experiments, blood pressure is often unreported or presented at extremely low levels (i.e. 60-80 mmHg vs &#62;100mmHg in a conscious mouse)2. The fragility of the cardiovascular system exhibited in an anesthetized mouse preparation often precludes meaningful assessment of autonomic nerve activity, given the codependent relationship between blood pressure and sympathetic tone3,4.
To address this limitation, a new method for direct recording of renal sympathetic nerve activity (RSNA) in conscious, unrestrained mice, undisturbed within their home cages was developed. Both the surgical and experimental approach for successful implementation of this technique is described in detail. This preparation enables the investigator to simultaneously record arterial pressure via radiotelemetry in addition to RSNA, with the added capability to intravenously infuse agents of interest without disturbing the mouse.
Twenty four hours post-surgery, mice behave normally and do not exhibit signs of pain or distress. Experimental recordings may then commence 48 to 72 hours post-surgery while the mouse rests comfortably in its home cage with unrestricted access to food, water and environmental enrichment. Clear RSNA traces are presented and the characteristic responses of this nerve population to normal physical movements of the animal (such as eating and grooming) are demonstrated in addition to pharmacological modulation of systemic blood pressure. The quality and specificity of the RSNA signal is further validated by ganglionic blockade. This manuscript includes the audiovisual complement to an initially published description of this technique5.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Teflon-coated stainless steel multiple stranded wire</td>
			<td>A-M Systems</td>
			<td>793200</td>
			<td>0.001in diameter bare; 0.0055in diameter coated</td>
		</tr>
		<tr>
			<td>#11 Scalpel Blade</td>
			<td>Fisher Scientific</td>
			<td>ALMM9011</td>
			<td></td>
		</tr>
		<tr>
			<td>Soldering Iron and solder</td>
			<td></td>
			<td></td>
			<td>Any make or model suitable</td>
		</tr>
		<tr>
			<td>Male miniature pin connectors</td>
			<td>A-M Systems</td>
			<td>520200</td>
			<td>Brass with gold plating</td>
		</tr>
		<tr>
			<td>Female miniature pin connectors</td>
			<td>A-M Systems</td>
			<td>520100</td>
			<td>Brass with gold plating</td>
		</tr>
		<tr>
			<td>Heat Shrink tubing</td>
			<td>Radio Shack</td>
			<td>Model #: 278-1610 |&#160;Catalog #: 2781610</td>
			<td>1.6 mm diameter</td>
		</tr>
		<tr>
			<td>Polyethylene 90 (PE90) tubing</td>
			<td>VWR</td>
			<td>CA-63018-703</td>
			<td>0.86mm inner diameter; 1.27mm outer diameter</td>
		</tr>
		<tr>
			<td>Dissecting microscope</td>
			<td>Leica Microsystems</td>
			<td>Leica M80</td>
			<td>Any make or model also suitable</td>
		</tr>
		<tr>
			<td>Polyethylene 10 (PE10) tubing</td>
			<td>Braintree Scientific</td>
			<td>PE10&#160;50 FT</td>
			<td>0.28mm inner diameter; 0.61mm outer diameter</td>
		</tr>
		<tr>
			<td>Super Glue Liquid</td>
			<td>Loctite</td>
			<td>n/a</td>
			<td>Liquid Formula; any brand suitable</td>
		</tr>
		<tr>
			<td>Super Glue Gel</td>
			<td>Loctite</td>
			<td>n/a</td>
			<td>Gel Formula; any brand suitable</td>
		</tr>
		<tr>
			<td>Polyethylene tubing</td>
			<td>Scientific Commodities</td>
			<td>BB31695-PE/13</td>
			<td>For pedestal 2.7mm inner diameter; 4.0mm outer diameter</td>
		</tr>
		<tr>
			<td>Hospital Sterilization Services &#38; Ozone Sterilization packets</td>
			<td></td>
			<td></td>
			<td>Contact local hospital sterilization services</td>
		</tr>
		<tr>
			<td>Isoflurane anesthesia</td>
			<td>Abbott</td>
			<td>05260-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Deltaphase isothermal heat pads &#38; surgical table</td>
			<td>Braintree Scientific</td>
			<td>39OP</td>
			<td>Keep heat pads warm in a 37&#176;C water bath; Corresponding surgical table essential</td>
		</tr>
		<tr>
			<td>Glycopyrrolate</td>
			<td>Amdipharm Mercury Company Limited</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane vaporizer system &#38; flow gauge</td>
			<td>Braintree Scientific</td>
			<td>VP I</td>
			<td>Include medical grade oxygen supply</td>
		</tr>
		<tr>
			<td>Tissue scissors</td>
			<td>Fine Science Tools</td>
			<td>14173-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine spring scissors</td>
			<td>Fine Science Tools</td>
			<td>15006-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Small cotton-tipped applicators</td>
			<td>Fisher Scientific</td>
			<td>23400100</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Straight Forceps</td>
			<td>Fine Science Tools</td>
			<td>11254-20</td>
			<td>#5, FST by Dumont Biologie Tip</td>
		</tr>
		<tr>
			<td>Angled Forceps</td>
			<td>Fine Science Tools</td>
			<td>11251-35</td>
			<td>#5/45 FST by Dumont</td>
		</tr>
		<tr>
			<td>Small Absorbent Spears</td>
			<td>Fine Science Tools</td>
			<td>18105-03</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Sigma Aldrich</td>
			<td>BR701605&#160;ALDRICH</td>
			<td></td>
		</tr>
		<tr>
			<td>Kwik-Sil 2 component Silicone Polymer</td>
			<td>World Precision Instruments (WPI)</td>
			<td>KWIK-SIL</td>
			<td>Purchase extra specialized tips from WPI</td>
		</tr>
		<tr>
			<td>5-0 Polysorb Suture</td>
			<td>Tyco Healthcare</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>6-0 Silk Suture</td>
			<td>Braintree Scientific</td>
			<td>SUT-S&#160;104</td>
			<td>Deknatel brand, spool</td>
		</tr>
		<tr>
			<td>Radiotelemetry Probe</td>
			<td>Data Sciences International (DSI)</td>
			<td>TA11-PAC10</td>
			<td></td>
		</tr>
		<tr>
			<td>Radiotelemetry Receiver</td>
			<td>Data Sciences International (DSI)</td>
			<td>PhysioTel RPC-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Ambient Pressure Reference</td>
			<td>Data Sciences International (DSI)</td>
			<td>Apr-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Pressure Output Adapter</td>
			<td>Data Sciences International (DSI)</td>
			<td>R11CPA</td>
			<td></td>
		</tr>
		<tr>
			<td>Rena Pulse Tubing</td>
			<td>Braintree Scientific</td>
			<td>RPT-040</td>
			<td></td>
		</tr>
		<tr>
			<td>Infusion Swivel</td>
			<td>Instech Solomon</td>
			<td>375/D/22</td>
			<td></td>
		</tr>
		<tr>
			<td>Swivel Support Arm &#38; Mount</td>
			<td>Instech Solomon</td>
			<td>SMCLA</td>
			<td></td>
		</tr>
		<tr>
			<td>Polysulfone button&#160;</td>
			<td>Instech Solomon</td>
			<td>LW62S/6</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless steel spring</td>
			<td>Instech Solomon</td>
			<td>PS62</td>
			<td></td>
		</tr>
		<tr>
			<td>Vetbond surgical adhesive</td>
			<td>3M</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Triple Antibiotic Ointment</td>
			<td>Fougera</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>PowerLab 8 Channel Data Acquisition System &#38; Software</td>
			<td>ADInstruments</td>
			<td>PowerLab 8/35</td>
			<td></td>
		</tr>
		<tr>
			<td>PVC Insulated Cable</td>
			<td>Belden</td>
			<td>PVC Audio Connection Cable 32 AWG</td>
			<td></td>
		</tr>
		<tr>
			<td>Preamplification Headstage</td>
			<td>Dagan Corporation</td>
			<td>Model 4002</td>
			<td></td>
		</tr>
		<tr>
			<td>Differential Amplifier</td>
			<td>Dagan Corporation</td>
			<td>EX4-400</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Nitroprusside</td>
			<td>Sigma Aldrich</td>
			<td>71778-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenylephrine</td>
			<td>Sigma Aldrich</td>
			<td>P6126-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Physiological Saline 0.9% NaCl</td>
			<td>Beckton Dickinson</td>
			<td></td>
			<td>Contact local hospital supplier</td>
		</tr>
		<tr>
			<td>hexamethonium</td>
			<td>Sigma Aldrich</td>
			<td>H0879-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless Steel top anti vibration table</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Custom designed in-house; Solid steel plate on a benchtop is also suitable</td>
		</tr>
		<tr>
			<td>Faraday cage</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Custom designed and constructed in-house</td>
		</tr>
		<tr>
			<td>Small animal hair trimmer</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Drugstore, men&#39;s beard trimmer suitable</td>
		</tr>
		<tr>
			<td>Dipilatory Cream</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Veet brand, sensitive skin formula</td>
		</tr>
		<tr>
			<td>10% Povidone Iodine</td>
			<td>Purdue Products</td>
			<td>Betadiene</td>
			<td></td>
		</tr>
		<tr>
			<td>70% Ethanol</td>
			<td>n/a</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Steel microretractors</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Made in-house. Bend a steel paper clip &#38; loop 4-0 silk to form a retractor</td>
		</tr>
		<tr>
			<td>Hemostats</td>
			<td>Fine Science Tools</td>
			<td>13011-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Heat Gun</td>
			<td>Fisher Scientific</td>
			<td>09-201-27</td>
			<td></td>
		</tr>
	</tbody>
</table>

novel approach for simultaneous recording of renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious, unrestrained mice.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity (RSNA) is of great interest in many areas of research such as chronic kidney disease, hypertension, heart failure, diabetes and obesity. Unequivocal assessment of the role of the sympathetic nervous system is thus imperative for proper interpretation of experimental results and understanding of disease processes. RSNA has been traditionally measured in anesthetized rodents, including mice. However, mice usually exhibit very low systemic blood pressure and hemodynamic instability for several hours during anesthesia and surgery. Meaningful interpretation of RSNA is confounded by this non-physiological state, given the intimate relationship between sympathetic nervous tone and cardiovascular status. To address this limitation of traditional approaches, we developed a new method for measuring RSNA in conscious, freely-moving mice. Mice were chronically instrumented with radio-telemeters for continuous monitoring of blood pressure as well as a jugular venous infusion catheter and custom-designed bipolar electrode for direct recording of RSNA. Following a 48-72 hour recovery period, survival rate was 100% and all mice behaved normally. At this time-point, RSNA was successfully recorded in 80% of mice, with viable signals acquired up to 4 and 5 days post-surgery in 70% and 50% of mice, respectively. Physiological blood pressures were recorded in all mice (116&plusmn;2 mmHg; n=10). Recorded RSNA increased with eating and grooming, as well-established in the literature. Furthermore, RSNA was validated by ganglionic blockade and modulation of blood pressure with pharmacological agents. Herein, an effective and manageable method for clear recording of RSNA in conscious, freely-moving mice is described.

Following the described protocol, survival rate was 100% - all mice instrumented in this study survived and recovered well following the surgical procedure. Within 24 hours of surgical preparation, all mice behaved normally, exhibiting typical eating, grooming and exploratory behaviors. No animals showed any sign of pain or distress at this time. 48 hours following surgery, a verifiable and clear RSNA signal was recorded in 10 out of the 12 mice. This signal was maintained in these mice 7...

Watch this Scientific Journal Video about Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice. at

Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity ...

novel-approach-for-simultaneous-recording-renal-sympathetic-nerve

Research

JoVE Journal

Medicine

10.0K Views.  University of Alberta. Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined. 

Video: Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Delivery of Therapeutic Agents Through Intracerebroventricular (ICV) and Intravenous (IV) Injection in Mice

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most often results in failure of potential therapeutics designed for neurodegenerative disorders 1,2. Neurodegenerative diseases such as Spinal Muscular Atrophy (SMA), in which the lower motor neurons are affected, can benefit greatly from introducing the therapeutic agents into the CNS. The purpose of this video is to demonstrate two different injection paradigms to deliver therapeutic materials into neonatal mice soon after birth. One of these methods is injecting directly into cerebral lateral ventricles (Intracerebroventricular) which results in delivery of materials into the CNS through the cerebrospinal fluid 3,4. The second method is a temporal vein injection (intravenous) that can introduce different therapeutics into the circulatory system, leading to systemic delivery including the CNS 5. Widespread transduction of the CNS is achievable if an appropriate viral vector and viral serotype is utilized. Visualization and utilization of the temporal vein for injection is feasible up to postnatal day 6. However, if the delivered material is intended to reach the CNS, these injections should take place while the blood brain barrier is more permeable due to its immature status, preferably prior to postnatal day 2. The fully developed blood brain barrier greatly limits the effectiveness of intravenous delivery. Both delivery systems are simple and effective once the surgical aptitude is achieved. They do not require any extensive surgical devices and can be performed by a single person. However, these techniques are not without challenges. The small size of postnatal day 2 pups and the subsequent small target areas can make the injections difficult to perform and initially challenging to replicate.

Delivery of Therapeutic Agents Through Intracerebroventricular ICV and Intravenous IV Injection in Mice

This article demonstrates two very different methods of injection: 1) into the brain (intracerebroventricular) and 2) systemic (intravenous) to introduce the therapeutic agents into the central nervous system of neonatal mice.

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most ...

Hyperinsulinemic-euglycemic Clamps in Conscious, Unrestrained Mice

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold standard" method for assessing insulin action in vivo. During an insulin clamp, hyperinsulinemia is achieved by a constant insulin infusion. Euglycemia is maintained via a concomitant glucose infusion at a variable rate. This variable glucose infusion rate (GIR) is determined by measuring blood glucose at brief intervals throughout the experiment and adjusting the GIR accordingly. The GIR is indicative of whole-body insulin action, as mice with enhanced insulin action require a greater GIR. The insulin clamp can incorporate administration of isotopic 2[14C]deoxyglucose to assess tissue-specific glucose uptake and [3-3H]glucose to assess the ability of insulin to suppress the rate of endogenous glucose appearance (endoRa), a marker of hepatic glucose production, and to stimulate the rate of whole-body glucose disappearance (Rd).
The miniaturization of the insulin clamp for use in genetic mouse models of metabolic disease has led to significant advances in diabetes research. Methods for performing insulin clamps vary between laboratories. It is important to note that the manner in which an insulin clamp is performed can significantly affect the results obtained. We have published a comprehensive assessment of different approaches to performing insulin clamps in conscious mice1 as well as an evaluation of the metabolic response of four commonly used inbred mouse strains using various clamp techniques2. Here we present a protocol for performing insulin clamps on conscious, unrestrained mice developed by the Vanderbilt Mouse Metabolic Phenotyping Center (MMPC; URL: www.mc.vanderbilt.edu/mmpc). This includes a description of the method for implanting catheters used during the insulin clamp. The protocol employed by the Vanderbilt MMPC utilizes a unique two-catheter system3. One catheter is inserted into the jugular vein for infusions. A second catheter is inserted into the carotid artery, which allows for blood sampling without the need to restrain or handle the mouse. This technique provides a significant advantage to the most common method for obtaining blood samples during insulin clamps which is to sample from the severed tip of the tail. Unlike this latter method, sampling from an arterial catheter is not stressful to the mouse1. We also describe methods for using isotopic tracer infusions to assess tissue-specific insulin action. We also provide guidelines for the appropriate presentation of results obtained from insulin clamps.

The hyperinsulinemic-euglycemic clamp, or insulin clamp, is the gold standard for assessing insulin action in vivo. A method for performing insulin clamps in mice is described. This includes a method for arterial catheterization that permits experiments to be performed in conscious, unrestrained mice with minimal stress.

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold ...

Femoral Arterial and Venous Catheterization for Blood Sampling, Drug Administration and Conscious Blood Pressure and Heart Rate Measurements

In multiple fields of study, access to the circulatory system in laboratory studies is necessary. Pharmacological studies in rats using chronically implanted catheters permit a researcher to effectively and humanely administer substances, perform repeated blood sampling and assists in conscious direct measurements of blood pressure and heart rate. Once the catheter is implanted long-term sampling is possible. Patency and catheter life depends on multiple factors including the lock solution used, flushing regimen and catheter material. This video will demonstrate the methodology of femoral artery and venous catheterization of the rat. In addition the video will demonstrate the use of the femoral venous and arterial catheters for blood sampling, drug administration and use of the arterial catheter in taking measurements of blood pressure and heart rate in a conscious freely-moving rat. A tether and harness attached to a swivel system will allow the animal to be housed and have samples taken by the researcher with minimal disruption to the animal. To maintain patency of the catheter, careful daily maintenance of the catheter is required using lock solution (100 U/ml heparinized saline), machine-ground blunt tip syringe needles and the use of syringe filters to minimize potential contamination. With careful aseptic surgical techniques, proper catheter materials and careful catheter maintenance techniques, it is possible to sustain patent catheters and healthy animals for long periods of time (several weeks).

Chronic catheterization of blood vessels in the rat is often required for administration of substances, obtain blood sample over a period of time or for direct conscious blood pressure measurements. Femoral arterial catheterization of the rat and corresponding measurements of blood pressure in the conscious animal will be demonstrated.

In multiple fields of study, access to the circulatory system in laboratory studies is necessary. Pharmacological studies in rats using chronically ...

Transcutaneous Assessment of Renal Function in Conscious Rodents

Glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional methods to evaluate GFR are cumbersome and time-consuming. In addition, serial blood or urine samples are required, with the associated stress for the experimental animals. A recent technique significantly reduces the investment in time and resources, minimizing the invasiveness and the animal stress, but being equally valid as the traditional approaches. The method measures transcutaneously renal function. Using an optical device and the exogenous renal marker fluorescein isothiocyanate (FITC)-sinistrin, this technique is capable of measuring the elimination kinetics of the marker through the skin. With neither blood nor urine samples nor the associated laboratory assays needed, the results of the transcutaneous measurement are almost instantaneously available. The method has been already validated in different species and successfully applied in several models of renal pathology. Moreover, due to its minimally invasive characteristics, it is suitable for sequential measurements within the same animal. Here is provided a detailed protocol to carry out the transcutaneous assessment of renal function in rodents.

Determination of glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional procedures to measure this parameter are cumbersome and require a large investment of time. Here we describe a faster and minimally invasive method to determinate GFR transcutaneously.

Glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional methods to evaluate GFR are cumbersome and ...

Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. Indeed, research focusing on the discovery of new potential therapeutic targets using genetically altered mice requires a reliable, long-term assessment of the systemic arterial pressure variation. Currently, the gold standard for obtaining long-term measurements of blood pressure in ambulatory mice uses implantable radio-transmitters, which require&#160;artery cannulation. This technique eliminates the need for tethering, restraining, or anesthetizing the animals which introduce stress and artifacts during data sampling. However, arterial blood pressure monitoring in mice via catheterization can be rather challenging due to the small size of the arteries. Here we present a step-by-step guide to illustrate the crucial key passages for a successful subcutaneous implantation of radio-transmitters and carotid artery cannulation in mice. We also include examples of long-term blood pressure activity taken from freely moving mice after a period of post-surgery recovery. Following this procedure will allow reliable direct blood pressure recordings from multiple animals simultaneously.

The goal of this protocol is to assess systemic blood pressure in conscious freely moving mice using implantable radio-telemetry devices.

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. ...

Cavernous Nerve Stimulation and Recording of Intracavernous Pressure in a Rat

The stimulation of the cavernous nerve (CN) and measurement of intracavernous pressure (ICP) have been used extensively to test and evaluate therapies for erectile dysfunction. However, the methods used vary between laboratories, and pitfalls still exist. The goal of this study was to describe a surgical technique that would provide a reliable and reproducible model. By exposing the ischiocavernosus muscle at its point of insertion on the ischial tuberosity, the penile crus could be cannulated with minimal dissection and injury to the structures involved in erectile function. Repeated stimulation of the CN, without the need for lifting and drying, was achieved by using a 125 &#181;m bipolar silver electrode and biocompatible silicon glue to isolate the electrode-nerve complex. This method prevents neuropraxia by reducing stretching and drying the nerve and provides complete isolation of the nerve, negating electrical leakage and preventing stimulation of alternative pathways.

This study describes a simplified surgical procedure and technique for performing cavernous nerve stimulation with the isolation of the nerve-electrode complex using silicone glue and intracavernous pressure measurement.

The stimulation of the cavernous nerve (CN) and measurement of intracavernous pressure (ICP) have been used extensively to test and evaluate therapies for ...

Non-invasive Assessment of Dorsiflexor Muscle Function in Mice

Assessment of skeletal muscle contractile function is an important measurement for both clinical and research purposes. Numerous conditions can negatively affect skeletal muscle. This can result in a loss of muscle mass (atrophy) and/or loss of muscle quality (reduced force per unit of muscle mass), both of which are prevalent in chronic disease, muscle-specific disease, immobilization, and aging (sarcopenia). Skeletal muscle function in animals can be evaluated by a range of different tests. All tests have limitations related to the physiological testing environment, and the selection of a specific test often depends on the nature of the experiments. Here, we describe an in vivo, non-invasive technique involving a helpful and easy assessment of force frequency-curve (FFC) in mice that can be performed on the same animal over time. This permits monitoring of disease progression and/or efficacy&#160;of a potential therapeutic treatment.

Measurement of rodent skeletal muscle contractile function is a useful tool that can be used to track disease progression as well as efficacy of therapeutic intervention. We describe here the non-invasive, in vivo assessment of the dorsiflexor muscles that can be repeated over time in the same mouse.

Assessment of skeletal muscle contractile function is an important measurement for both clinical and research purposes. Numerous conditions can negatively ...

Simultaneous Electrocardiography Recording and Invasive Blood Pressure Measurement in Rats

For studies related to cardiovascular physiology or pathophysiology, blood pressure (BP) and electrocardiography are basic observational parameters. Research focusing on cardiovascular disease models, potential cardiovascular therapeutic targets or pharmaceutical agents requires assessment of systemic arterial pressure and heart rhythm changes. In situations where radio telemetry systems are not available or affordable, the technique of femoral artery cannulation is an alternative way to obtain intra-arterial pressure waveform recordings and systemic BP measurements. This technique is economical and can be performed with standard equipment in animal facilities. However, invasive arterial pressure recording requires cannulation of small arteries, which can be a challenging surgical skill. Here, we present step-by-step protocols for femoral artery cannulation procedures. Key procedures include the calibration of the data acquisition system, tissue dissection and femoral artery cannulation, and setup of the arterial cannulation system for pressure recording. Surface electrocardiography recording procedures are also included. We also present examples of BP recordings from normotensive and hypertensive rats. This protocol allows reliable direct recordings of systemic BP with simultaneous electrocardiography.

Here, we describe a setup for simultaneous recording of electrocardiography and intra-arterial blood pressure (BP) in experimental rats, which can be done with standard equipment in animal facilities and can be applied to physiological or pharmacological studies to investigate pathogenic or therapeutic mechanisms in cardiovascular medicine.

For studies related to cardiovascular physiology or pathophysiology, blood pressure (BP) and electrocardiography are basic observational parameters. ...

Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. The baroreflex is a key homeostatic mechanism to counteract acute, short-term changes in arterial BP and to maintain BP in a relatively narrow physiological range. BP is sensed by baroreceptors located in the aortic arch and carotid sinus. When BP changes, signals are transmitted to the central nervous system and are then communicated to the parasympathetic and sympathetic branches of the autonomic nervous system to adjust HR. A rise in BP causes a reflex decrease in HR, a drop in BP causes a reflex increase in HR.
Baroreflex sensitivity (BRS) is the quantitative relationship between changes in arterial BP and corresponding changes in HR. Cardiovascular diseases are often associated with impaired baroreflex function. In various studies reduced BRS has been reported in e.g., heart failure, myocardial infarction, or coronary artery disease. 
Determination of BRS requires information from both BP and HR, which can be recorded simultaneously using telemetric devices. The surgical procedure is described beginning with the insertion of the pressure sensor into the left carotid artery and positioning of its tip in the aortic arch to monitor arterial pressure followed by the subcutaneous placement of the transmitter and ECG electrodes. We also describe postoperative intensive care and analgesic management. After a two-week period of post-surgery recovery long-term ECG and BP recordings are performed in conscious and unrestrained mice. Finally, we include examples of high-quality recordings and the analysis of spontaneous baroreceptor sensitivity using the sequence method.

The baroreflex is a heart-rate regulation mechanism by the autonomic nervous system in response to blood-pressure changes. We describe a surgical technique to implant telemetry transmitters for continuous and simultaneous measurement of electrocardiogram and blood pressure in mice. This can determine spontaneous baroreflex sensitivity, an important prognostic marker for cardiovascular disease.

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. ...

Repetitive Blood Sampling from the Subclavian Vein of Conscious Rat

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to detect drug exposure. The rat blood sampling method determines the quality of the plasma and further affects the precision of the test results. The subclavian vein blood collection method described in this protocol collects blood samples repeatedly in the conscious state of animals to meet the needs of PK and TK tests. The skills of restraint handling and appropriate procedure of needle incision ensure the success rate of blood collection. It is easy to operate while ensuring the quality of plasma and at the same time catering to animal welfare. However, this method requires skilled operation, and an improper one may cause animal weakness, pain, lameness, and even mortality. The current method has been used in the testing facility for a 4-week oral toxicity study in Sprague Dawley (SD) rats with TK. The maximum amount of blood collected within 24 h did not exceed 20% of the animal's total blood. The animals' body weight was more than 200 g for males and females. The data showed that the animals' bodyweight increased steadily every week, and the clinical observation was normal after repetitive sample collection.

The present protocol describes a simple and efficient method for collecting blood from the subclavian vein in rats. It enables rapid, timely, and easily identifiable sampling without anesthesia and obtains high-quality blood through repetitive sample collection.

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to ...