PHYSIOLOGICAL BASIS FOR EFFECTS OF LOW-PROTEIN DIETS ON BLOOD PRESSURE OF SUBTOTALLY NEPHRECTOMIZED RAT

Abstract

The ingestion of low-protein diets supplemented with choline and cystine results in the disappearance of hypertension in partially nephrectomized rats. The addition to low-protein diets of methionine, phenylalanine or tyrosine is without effect on the blood pressure of such animals. Choline, when fed in excess, resulted in moderate hypertension. Glutamic acid and gelatin added to low-protein diets induced a hypertension equivalent to that occasioned by urea in such animals. Admn. of 1 mg. ACTH per day was essentially without effect on the blood pressure of unoperated control rats or on the blood pressure of partially nephrectomized, hypertensive rats ingesting a high-protein ration. The same dosage of ACTH promptly raised the blood pressure of subtotally nephrectomized rats, living on low-protein rations, to the levels maintained by comparable animals on high-protein rations. This effect was equally apparent in rats ingesting a diet low in protein and of markedly reduced Na content. Evidence is presented which indicates that the elaboration of ACTH is markedly reduced by the ingestion of a low-protein diet and it is concluded that the reduction in blood pressure which is effected by feeding a low-protein diet to partially nephrectomized rats is, in large measure, due to this failure of ACTH synthesis.