Dec 1, 1990

Wenckebach periodicity in single atrioventricular nodal cells from the rabbit heart

Circulation
K HoshinoJ Jalife

Abstract

Previous studies have suggested that Wenckebach periodicity in cardiac tissues may occur because of discontinuous propagation across junctional areas in which there is high intercellular resistivity or different cell types. Under these conditions, the impulse may stop altogether at a given junction, or may renew its propagation but only after a step delay imposed by the diastolic time-dependent recovery in the excitability of cells distal to that junction. Accordingly, Wenckebach periodicity in the atrioventricular node may be explained in terms of electrotonically mediated delay in the activation of the nodal cells. To test this hypothesis, we have studied recovery of excitability, and susceptibility to rate-dependent activation failure in single myocytes isolated from the adult rabbit atrioventricular node. Recordings were obtained by using the patch technique in the whole-cell, current clamp configuration. Repetitive stimulation of single atrioventricular nodal myocytes with depolarizing current pulses of critical amplitude yielded frequency-dependent stimulus response patterns that ranged from 1:1, through various Wenckebachlike periodicities (e.g., 5:4 and 4:3) to 2:1 and 3:1. Both typical and atypical Wenckebach structure...Continue Reading

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Citations

Mentioned in this Paper

Periodicity
Resting Potentials
Refractory Period, Electrophysiological
Chinchilla Rabbits
Structure of Atrioventricular Node
Familial Mediterranean Fever
Sick Sinus Syndrome
Nerve Impulses
Metazoa
Electric Stimulation Technique

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