Mechanisms Responsible for the Elevated Blood Pressure in the Cerebral Hypertensive Rabbit

Abstract

The blood pressure responses to Nembutal, and/or epinephrine and norepinephrine were observed in cerebral hypertensive (produced by bilateral ligation of the internal and external carotid arteries), renal hypertensive (partial occlusion of one renal artery), and normotensive rabbits. Nembutal anesthesia reduced the blood pressure 19, 7.6 and 9.6% in the cerebral, renal and normotensive rabbits, respectively. Pressor responses to a given dose of epinephrine or norepinephrine in the unanes-thetized animal were twice as great in the renal as in the normal control. In turn, the cerebral response was only half that of the normotensive control. Cerebral pressor response to epinephrine or norepinephrine after Nembutal anesthesia was similar to that of the normal. The intracranial pressure was elevated to 145 cm saline in 3 control rabbits. Responses of these 3 animals to norepinephrine were similar to those of the unanesthetized cerebral. Based on the results it is suggested that an increased sympathetic activity may be involved in the maintenance of the hypertension in the cerebral hypertensive rabbit.