Mechanism of Slow Conduction at the Bulbo-ventricular Junction

Abstract

Delay of conduction of excitation from the ventricle to the bulbus cordis in the frog heart occurred mainly in the narrow junctional area on the ventricular side of the bulbus cordis tissue. The action potential of this tissue was different from that seen in the bulbus cordis and the ventricle, showing a low rate of depolarization and low resting potential. Several physiological phenomena which have been observed in this junctional tissue can also be seen in the A-V nodal tissue. Histological studies revealed a difference in the direction of fibers and the presence of special cells in the junctional tissue. The mechanism responsible for the low conduction velocity in this area can be attributed, in part, to the histological arrangement found in the junctional tissue.