IMPORTANCE OF DIETARY PROTEIN, CALORIES AND SALT IN EXPERIMENTAL RENAL HYPERTENSION

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Abstract
Purified synthetic uiets were used in a study of the effects of various nutritional factors on the blood pressure of adult male rats rendered hypertensive by sub-total nephrectomy. It was found that the dietary levels of protein, calories, and salt independently exert a profound influence on systolic blood pressure. The effect of protein was detd. at 3 dietary levels, all of which supported rat growth under these conditions. In rats ingesting diets of normal salt content, systolic pressures stabilized at the following levels: high protein, 168 mm.; medium protein, 145 mm.; low protein, 122 mm. While urea, added to a low protein ration, exerted a slight pressor effect, it was not sufficient to account for the observed effects of dietary protein. The addition to a low protein diet of tyrosine and phenylalanine, in the amts. present in a 50% casein diet, had no effect on blood pressure. Restriction of daily food consumption, to an amt. just adequate to permit wt. maintenance or very slow growth, resulted in a fall to virtually normal pressures on all diets but that containing an unusually excessive amt. of salt. Drastic reduction of the Na content of the diet only slightly reduced the systolic pressures of rats on high protein rations. Addition of 3% NaCl (ten times the normal level) to a low protein ration resulted in marked hypertension.