THE SIGNIFICANCE OF CAROTID SINUS REFLEXES FOR THE EFFECTS OF ANOXIA AND CARBON DIOXIDE ON CONVULSIONS

Abstract

The influence of anoxia and of inhalation of CO2 was investigated on chemically induced convulsions in the narcotized cat. Anoxia promptly abolished convulsions in the cat whose carotid sinus nerves and vagi had been cut, whereas it exerted no or a very slight inhibitory effect on the normal animal. CO2 was a powerful inhibitory agent as far as convulsions are concerned in the normal animal, but failed to show such effects after the denervation of the carotid sinuses and bilateral vagotomy. The peculiar reversal in the efficacy of CO2 and anoxia which is produced by the elimination of the buffer nerves is explained by the fact that variations in the tension of O2 and CO2 in the blood and tissues modify in opposite directions the depressor reflexes originating in the carotid sinus and arch of the aorta.