title: Comparison of sympathetic nerve activity normalization procedures in conscious rabbits.
abstract: One of the main constraints associated with recording sympathetic nerve activity (SNA) in both humans and experimental animals is that microvolt values reflect characteristics of the recording conditions and limit comparisons between different experimental groups. The nasopharyngeal response has been validated for normalizing renal SNA (RSNA) in conscious rabbits, and in humans muscle SNA is normalized to the maximum burst in the resting period. We compared these two methods of normalization to determine whether either could detect elevated RSNA in hypertensive rabbits compared with normotensive controls. We also tested whether either method eliminated differences based only on different recording conditions by separating RSNA of control (sham) rabbits into two groups with low or high microvolts. Hypertension was induced by 5 wk of renal clipping (2K1C), 3 wk of high-fat diet (HFD), or 3 mo infusion of a low dose of angiotensin (ANG II). Normalization to the nasopharyngeal response revealed RSNA that was 88, 51, and 34% greater in 2K1C, HFD, and ANG II rabbits, respectively, than shams (P < 0.05), but normalization to the maximum burst showed no differences. The RSNA baroreflex followed a similar pattern whether RSNA was expressed in microvolts or normalized. Both methods abolished the difference between low and high microvolt RSNA. These results suggest that maximum burst amplitude is a useful technique for minimizing differences between recording conditions but is unable to detect real differences between groups. We conclude that the nasopharyngeal reflex is the superior method for normalizing sympathetic recordings in conscious rabbits.
authors.affiliation: Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; and.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Burke
authors.affiliation: Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; and.
authors.forename: Kyungjoon
authors.initials: K
authors.lastname: Lim
authors.affiliation: Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; and.
authors.forename: John-Luis
authors.initials: JL
authors.lastname: Moretti
authors.affiliation: Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; and Department of Pharmacology, Monash University, Clayton, Victoria, Australia geoff.head@baker.edu.au.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Head
mesh_terms: D000200:Action Potentials; D000804:Angiotensin II; D000818:Animals; D062186:Arterial Pressure; D017704:Baroreflex; D001795:Blood Pressure Determination / Q000379:methods; D002138:Calibration; D003243:Consciousness; D003250:Constriction; D059305:Diet, High-Fat; D004195:Disease Models, Animal; D004568:Electrodiagnosis / Q000379:methods* / Q000592:standards; D006339:Heart Rate; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology*; D007668:Kidney / Q000294:innervation*; D008297:Male; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000294:innervation*; D009305:Nasopharynx / Q000294:innervation*; D011817:Rabbits; D012077:Renal Artery / Q000503:physiopathology / Q000601:surgery; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013686:Telemetry / Q000379:methods; D013997:Time Factors
chemical_list: D000804:Angiotensin II
keywords: blood pressure; hypertension; nasopharyngeal stimulation; normalization method; rabbit