[DNA synthesis in myocytes of the heart conduction system in myocardial infarction induced in young rats].

The myocardial infarction was induced in 13- and 21-day-old rats. The extent of the DNA synthesis activation in myocytes of conduction system compartments compared with atrial and ventricular myocytes was evaluated by cumulative indices of labeled nuclei after 30-times-repeated 2H-thymidine injections at 12h intervals. Labeling indices in atrial myocytes are two to six times higher (0.01 < P < 0.001) in rats with infarction than in control. On the contrary, in conduction system compartments there are no statistically significant differences between control and experimental groups (P > 0.05). An activation of DNA synthesis can occur in myocytes of His bundle in some animals.