THE RÔLE OF THE HYPOTHALAMUS AND PREOPTIC REGION IN THE REGULATION OF HEART RATE

Abstract

Under chloralose anesthesia, the preoptic region and hypothalamus of 24 normal cats were stimulated. The pulse and blood pressure were recorded from the carotid artery. An avg. increase of heart rate of 5-25% was demonstrated following a 30-sec. stimulation of the hypothalamus. This tachycardia is largely effected through the cardiosympathetic nerves and adrenin, and can be obtained differentially without the accompanying hypertension in animals with the abdominal vessels tied at the level of the diaphragm. Stimulation of the preoptic region resulted in an avg. slowing of the heart of 6-19%. The effect is partly vagal.