Effect of stimulation of the hypothalamus on the activity of the cardiovascular system in long-term experiments

Abstract

In chronic experiments on waking unanesthetized dogs a study was made of the effect produced by stimulating various portions of the hypothalamus on the blood pressure and the frequency of cardiac contractions. Blood pressure was recorded in the coronary artery or in the subcutaneous artery of the knee joint. As demonstrated, stimulation of the posterior hypothalamus (caudal portion of the tuber cinereum and of the mamillary body) increased the blood pressure by 20–40 mm Hg, whereas stimulation of the anterior hypothalamus (the area of the supraoptic and paraventricular nuclei) decreased the pressure in a number of cases by 10–20 mm Hg. The frequency of cardiac contraction usually increased by 10–14 (at times by 60 beats) per minute; the rise in response to stimulation of the anterior hypothalamus was less pronounced. In individual cases there was an insignificant deceleration of the cardiac rhythm by 4–8 contractions per minute. Other autonomic and somatic reactions often accompanied the blood pressure and pulse changes, i.e., the pupil size changes, those of respiration, of the smelling reaction, licking, urination, defecation, general motor excitation, etc.