On the changes in the atrioventricular conduction time under the effect of acetylcholine.

The aim of the present investigation is to study the effect of acetylcholine on the atrioventricular (AV) conduction time in preparation from rabbit heart right atrium. The artrial electrogram and the action potentials of the His-cells are recorded by means of bipolar electrodes and microelectrodes. The effect of acetylcholine is assessed by the simultaneous changes in the period of the atrial complexes and in the atrioventricular conduction time. The significance of the prolonged period of the atrial complexes for the compensation of the acetylcholine effect on the node area of the conduction system is pointed out. A considerable increase in the refractory periods of the atrioventricular node is found.