Nitric oxide donors dose-dependently reduce heart rate in rats against the background of blood pressure drop

The effect of nitroglycerin in increasing doses (0.2-1.0 mg/kg) and sodium nitroprusside (1 mg/kg) on the heart rate, P-Q interval of ECG, and blood pressure was studied on 53 albino rats. NO donors nitroglycerin and sodium nitroprusside directly affected vascular endothelium (the maximum decrease in blood pressure was 28.5 and 57.0%, respectively) and produced a dose-dependent negative chronotropic effect (the maximum decrease in heart rate was 13.6 and 27.0%, respectively). These drugs also affected myocytes of the cardiac conduction system: P-Q interval increased by 16.0-29.7%.