[The effect of acetylcholine on passive electrical properties and intercellular electrical communications in the sinoatrial node of the rabbit heart].

The effect of acetylcholine (ACH) on passive electric properties and intercellular coupling was studied using microelectrode technique in experiments on isolated preparations of the sinoatrial area of the rabbit's heart. The space constant of electrotonic decay (lambda delta) and input resistance (RBX) were measured. ACH was found to reduce lambda delta and increase RBX. Analysis of the experimental data, using the model of thin layer 3-dimensional syncytium, revealed that ACH of 10(-7) M, 10(-6) M and 10(-5) M increased the resistance of intracellular syncytium by factor of 1.25, 1.36 and 1.43, respectively, and decreased the resistance of the electrogenic membrane by factor of 1.13, 1.12 and 1.23, respectively. It is concluded that ACH increases the resistance of intercellular contacts in the sinoatrial node.