[Heart rate regulation during depressor reflexes]

Chronic experiments on cats were made to study the relationship between reflex tachycardia in response to the drug-induced arterial blood pressure fall and spontaneous variations in the initial cardiac rhythm. The existence of inverse linear correlation was shown between the magnitude of chronotropic response and control heart rate before and after beta-adrenergic blockade. The significance of the correlation disclosed for the interpretation of the research data on the relative role of the sympathetic and parasympathetic heart regulation performed in different experimental conditions is discussed.