Optical mapping of atrioventricular node reveals a conduction barrier between atrial and nodal cells

The American Journal of Physiology
B R Choi, G Salama

Abstract

The mechanisms responsible for atrioventricular (AV) delay remain unclear, in part due to the inability to map electrical activity by conventional microelectrode techniques. In this study, voltage-sensitive dyes and imaging techniques were refined to detect action potentials (APs) from the small cells comprising the AV node and to map activation from the "compact" node. Optical APs (124) were recorded from 5 x 5 mm (approximately 0.5-mm depth) AV zones of perfused rabbit hearts stained with a voltage-sensitive dye. Signals from the node exhibited a set of three spikes; the first and third (peaks I and III) were coincident with atrial (A) and ventricular (V) electrograms, respectively. The second spike (peak II) represented the firing of midnodal (N) and/or lower nodal (NH) cell APs as indicated by their small amplitude, propagation pattern, location determined from superimposition of activation maps and histological sections of the node region, dependence on depth of focus, and insensitivity to tetrodotoxin (TTX). AV delays consisted of tau 1 (49.5 +/- 6.59 ms, 300-ms cycle length), the interval between peaks I and II (perhaps AN to N cells), and tau 2 (57.57 +/- 5.15 ms), the interval between peaks II and III (N to V cells). T...Continue Reading

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Citations

Mar 15, 2001·American Journal of Physiology. Heart and Circulatory Physiology·M RestivoM Boutjdir
Jun 8, 2001·News in Physiological Sciences : an International Journal of Physiology Produced Jointly by the International Union of Physiological Sciences and the American Physiological Society·Guy Salama, Bum-Rak Choi
Aug 20, 2021·Frontiers in Bioengineering and Biotechnology·Nataliia Naumova, Laura Iop

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