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Central parasympathetic activation assessed by cardiac vagal motoneuron recordings in rat

Abstract : The parasympathetic supply to the heart is responsible for the short-term regulation of blood pressure (BP), by controlling the heart rate (HR) on a beat-by-beat basis. Decreased cardiac vagal activity is considered an index of poor outcome. The vagal projection of the nucleus ambiguus on the heart is the common pathway for different cardiac reflexes, like the cardiac baroreflex and the von Bezold- Jarisch (BJ) chemoreflex. Recent advances in extracellular recording methods of cardiac vagal motoneurons (CVM) in rat made easier the exploring of these two reflexes. Thus, a better understanding of the mechanisms and sites of action of two drugs could be achieved. 1). An α-2 adrenergic agonist, clonidine, a central hypotensive, influences the short-term regulation of BP. The present work shows an increase of the activity of CVM, together with the slope of the cardiac baroreflex at central level (BP-CVM relationship) when clonidine is administered systemically, in cumulative doses (10-100µg/kg i.v.). A deeper analysis of the CVM activity revealed a possible new mechanism of action of clonidine by fast firing (“doublet”). 2). B-type natriuretic peptide (BNP), used in the treatment of the heart failure, increased significantly the bradycardia and the CVM activity during the activation of the BJ reflex. The bradycardia is proportional to the vagal activation. This proves, by subtractive logic, that the BNP site of action is on the afferent arm of the reflex. Cardiac vagal activation is a solution in the treatment of cardiovascular disorders
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Submitted on : Thursday, June 26, 2008 - 4:23:06 PM
Last modification on : Wednesday, November 20, 2019 - 3:14:56 AM
Long-term archiving on: : Friday, May 28, 2010 - 10:53:45 PM

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Emil Toader. Central parasympathetic activation assessed by cardiac vagal motoneuron recordings in rat. Tissues and Organs [q-bio.TO]. Université Claude Bernard - Lyon I, 2008. English. ⟨tel-00291046⟩

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