Increases in urinary kallikrein activity and prostanoid synthesis after dietary potassium supplementation

1. To determine whether increasing dietary potassium alters kallikrein activity or prostaglandin synthesis, 77 women participated in a 3 week screening to assess their dietary potassium intake. Forty-four normotensive women whose dietary potassium was less than 60 mmol/day were allocated randomly to one of two groups who took either 80 mmol/day KCl (Slow-K, Ciba Geigy) or matching placebo for the first or second of two 4 week periods. 2. Significant increases in urinary kallikrein excretion (P less than 0.01), and urinary 6-keto-PGF1 alpha (P less than 0.01) were observed during potassium supplementation. These changes occurred without alterations in urine volume or sodium excretion. 3. It is suggested that potassium-induced changes in urinary 6-keto-PGF1 alpha may reflect increased renal and possibly vascular synthesis of prostacyclin. These increases may be mediated by increased plasma potassium stimulating kallikrein synthesis, leading to bradykinin-induced activation of phospholipase A2. Enhanced kallikrein/kinin and prostacyclin formation could contribute to the blood pressure lowering effect of potassium reported in hypertensive subjects.