PMID: 3752273Sep 1, 1986Paper

Vagally induced hyperpolarization in atrioventricular node

The American Journal of Physiology
Todor N MazgalevA Pelleg

Abstract

The effects of postganglionic vagal stimulation on atrioventricular nodal conduction were studied in 12 rabbit atrial-atrioventricular nodal preparations. Vagal stimulation was introduced in the sinus and atrioventricular nodes, separately or in combination, using single bursts of subthreshold stimuli. The sinus cycle length was scanned to identify the phasic effect of vagal stimulation. Action potentials from cells in the AN, N, and NH regions of the atrioventricular node were recorded by microelectrode techniques. Vagally induced hyperpolarization of cells in the atrioventricular node resulted in a phase-dependent prolongation of conduction time and reflected the level of residual hyperpolarization at the moment of arrival of the next atrial beat at the atrioventricular nodal input region. Vagally induced hyperpolarization was membrane potential dependent, although its overall time course was similar at different phases. Increased diastolic depolarization followed the maximal hyperpolarization. This "rebound" observed at certain phases was responsible for paradoxical shortening of the conduction time after vagal stimulation. The predominant effects of local vagal stimulation in the atrioventricular node were observed in cells...Continue Reading

Citations

Jan 25, 2000·American Journal of Physiology. Heart and Circulatory Physiology·P SchiereckW L Mosterd

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