Morphological analysis of myocyte relationships in the sinoatrial node in rats.

The presence of action potentials of working atrial cardiomyocytes among action potentials of true and latent pacemakers was revealed in the part of bidimentional maps of distribution of action potentials of sinoatrial node cells on the frontal surface of the right atrium under conditions of short-term culturing using intracellular glass microelectrodes. Detailed submicroscopical analysis of the node tissue was conducted. Sinoatrial node of rat heart consists of typical nodal cells and transition-type cardiomyocytes. Working atrial cardiomyocytes are absent in the tissue of the node. Action potentials of atrial cardiomyocytes among true and latent pacemakers in the course of electrophysiological study are recorded from cells of working myocardium of the thin subepicardial plate coverig the sinoatrial node.