THE ROLE OF THE HYPOPHYSIS AND ADRENALS IN THE CONTROL OF SYSTOLIC BLOOD PRESSURE IN THE RAT1

Abstract

Systolic blood pressure of the rat was studied in unanesthetized adult [male][male] following adrenalectomy, hypo-physectomy, and after adm. of adrenal hormones. Normal blood pressures ranged between 110 and 120 mm. Hg. Adrenalectomy caused a sharp decrease in blood pressure which averaged 60 mm. 6 days postoperatively. A slight rise may occur followed by a fall in pressure below 60 mm. and death of the animal. Hypophysectomy was followed by a decrease in pressure to 80 mm., which was maintained for as long as 7 mos. A daily dosage of DCA (0.05 mg.) failed to prevent the drop in pressure following hypophysectomy. This dosage of DCA seldom caused a mild hypertension in normal rats. Large doses of adrenal cortical extract, however, partially prevented the decrease in blood pressure following hypophysectomy. It would appear that some factor in addition to the loss of cortical hormone is responsible for the lowering of systolic blood pressure after hypophysectomy in rats.