The renal kallikrein-kinin system in various types of diuresis and under the effects of inhibitors of prostaglandin synthesis in rats.

In rats with water load, rats with high-salt diet, rats treated with furosemide, and rats treated with indomethacin in low doses (2 mg/kg orally per day for five consecutive days) an enhanced urinary excretion of kallikrein was observed. Higher dosage of indomethacin (5 mg/kg), on the contrary, markedly reduced the urinary kallikrein excretion. The degree of activation of the renal kallikrein-kinin system was lowest in water diuresis, and highest at the high-salt diet. In salt- and furosemide-induced diuresis, positive correlations were found between the urinary kallikrein excretion, sodium excretion, urine flow rate, and renal concentration capacity. In water diuresis, a positive correlation was found solely between the kallikrein excretion and the urine flow rate. Indomethacin at low dosages elevated, and at high dosages reduced the activity of the renal kallikrein-kinin system; analogous effects were exerted on the urine flow rate and on sodium excretion.