High potassium intake selectively increases urinary PGF2 alpha excretion in the rat.

This study was designed to investigate relationships between dietary potassium and the renal prostaglandin system in rats. The potassium content of the diet was 0.162 mmol/g during the control period and 0.004, 0.162, 1.351, or 2.702 mmol/g during the experimental period. Relative to control data in rats fed a 0.162 mmol/g potassium diet, the urinary excretion of 6-keto-PGF1 alpha was not affected by high potassium intake but increased (P less than 0.05) by 25% in rats fed a low potassium diet for 13 days and was associated with reduction of plasma potassium and with elevation of both plasma renin and net release of 6-keto-PGF1 alpha from renal inner medulla slices incubated in Krebs solution. The excretion of PGF2 alpha was not affected by low potassium intake but increased (P less than 0.05) by about twofold in rats fed a potassium-rich diet (1.351 and 2.702 mmol/g) for 13 days and was associated with elevation of plasma potassium concentration, renal prostaglandin 9-keto-reductase activity, and urinary excretion of kallikrein and vasopressin. The urinary excretion of PGE2 was not altered in rats fed either low or high potassium diets. Altogether, these results indicate selective influence of dietary potassium on the urinary excretion of prostaglandins in the rat.