Dietary potassium and the development of hypertension in two-kidney, one clip Goldblatt hypertensive rats.

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Abstract
Experiments were designed to test the hypothesis that a decrease in the molar ratio of Na to K (from 5 to 0.2) in a diet of constant total electrolyte content would decrease renin and aldosterone levels or result in a diuresis and natriuresis that would attenuate the development of hypertension in 2-kidney, 1 clip Goldblatt hypertensive rats. Measurements of blood pressure, renin-angiotensin-aldosterone activities, and metabolic balance wre compared for groups of clipped or sham-clipped rats that were maintained on diets of altered Na-K content initiated at the time of clipping. Four weeks of dietary treatment following application of a 0.25 mm clip to 1 renal artery resulted in significantly higher plasma renin activity for animals on the 1:5 Na/K ratio diet, (13.5 .+-. ng AI/ml .cntdot. h, compared to 5.6 0.7 ng AI/ml .cntdot. h for rats on the 1:1 Na/K diet, or 7.1 .+-. 0.8 ng AI/ml .cntdot. h for rats on the 5:1 Na/K ratio diet, P < 0.05). Urinary free aldosterone was also signifiacntly (P < 0.01) higher in animals on the 1:5 Na/K diet (22.5 .+-. 1.3 .mu.g/24 h compared to 10.9 .+-. 1.3 .mu.g/24 h on the 1:1 Na/K ratio diet and 14.4 .+-. 0.5 .mu.g/24 h on the 5:1 Na/K diet). Variations in plasma renin activity and aldosterone induced by altering the ratio of Na to K in the diet were not associated with detectable differences in the level of blood pressure between the dietary sets of animals that were either clipped or sham-clipped. Nine days after placement of a 0.2 mm clip on 1 renal artery in different groups of rats, the mean systolic blood pressure for animals on the 1:1 Na/K ratio diet was 141 .+-. 4 mm Hg, that for animals on the 1:5 Na/K ratio diet was 141 .+-. 7 mm Hg, and that for animals on the 5:1 Na/K ratio diet was 144 .+-. 3 mm Hg. There were no significant differences in blood pressure at any time during the period of study between any of the diet treatment groups. Metabolic balance studies failed to reveal significant differences in weight gain, food intake, water consumption, urine output or fractional recovery of Na or K between any of the dietary sets for the clipped group or the sham group of animals. Apparently, altered molar ratios of dietary Na/K do not affect the course of blood pressure in the 2-kidney, 1 clip Goldblatt hypertensive rat when total electrolyte content for the various diets is maintained at a constant level.