Effects of rat sinoaortic denervation on the vagal responsiveness and expression of muscarinic acetylcholine receptors

Journal of Cardiovascular Pharmacology
Pedro Paulo da Silva SoaresM C Irigoyen

Abstract

We studied heart rate (HR) responses to vagal electrical stimulation (VES) and the expression of muscarinic acetylcholine receptors (mAChRs) in the rat atria 1 day (SADa) and 20 days (SADc) after sinoaortic denervation (SAD). Arterial blood pressure (BP) was recorded in conscious, unrestrained rats and during vagal electrical stimulation of the vagus nerve. In the acute phase, SADa rats had hypertension, tachycardia, and increased blood pressure lability. In the chronic phase, heart rate and blood pressure in SADc rats returned to normal whereas blood pressure lability remained increased. VES produced a frequency-dependent bradycardia that was higher in SADa and SADc groups. Binding experiments with [H] N-methylscopolamine showed that in the chronic phase of SAD mAChRs density (SADc = 412.2 +/- 28.64, SADa = 273.38 +/- 48.37 and CTR = 241.5 +/- 25.35 fmol/mg of protein, P < 0.05) and affinity increased in SADc rats (reduced dissociation constant: SADc = 0.45 +/- 0.05, SADa = 1.01+/-0.26, and CTR = 0.98 +/- 0.12 mM, P < 0.05). Our study provides evidence that vagal hyperresponsiveness coexists with increased sympathetic activity in SADa rats without a concomitant increase in mAChRs density or affinity, suggesting that complex me...Continue Reading

Citations

Jul 6, 2010·American Journal of Physiology. Heart and Circulatory Physiology·Brett A EnglishRandy D Blakely
Nov 21, 2019·Clinical and Experimental Hypertension : CHE·Élida Mercês Raimundo FernadesLenice Kappes Becker
Dec 15, 2020·Scientific Reports·Nathalia Juocys Dias MoreiraMaria Cláudia Costa Irigoyen

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