Dependence of Protoveratrine-induced Hypotension on the Hypothalamus.

Summary In view of the fact that baroreceptor reflexes depend on excitability of the hypothalamus and that Protoveratrine elicits these reflexes, the action of Protoveratrine in relation to hypothalamic excitability was investigated in the cat. It was found: 1. That injection of barbiturates into the lateral and posterior hypothalamus practically abolishes the Protoveratrine-induced hypotension. This effect is reversible. 2. That lesions confined chiefly to the lateral hypothalamus exert a similar but irreversible effect. Such lesions do not interfere with the hypertensive action of larger doses of Protoveratrine. 3. That barbiturates administered intraperitoneally in anesthetic concentrations eliminate the hypotensive action of Protoveratrine.