Effect of furosemide on urinary kallikrein excretion in patients with essential hypertension.

The effect of furosemide on urinary kallikrein excretion was studied in 10 patients with essential hypertension and 9 normal volunteer subjects. After intravenous administration of furosemide and 2 hours of upright posture, urine volume (UV), urinary sodium (UNaV) and potassium (UKV) excretion, plasma renin activity (PRA), plasma aldosterone concentration (PAC) and urinary kallikrein markedly increased. However, the augmentation of urinary kallikrein in patients with essential hypertension (1.50 +/- 0.19 EU/2 hr) was less remarkable than that in normal subjects (2.33 +/- 0.24 EU/2 hr), although the same degrees of response were observed in PRA and PAC. The increments of UV, UNaV and UKV in patients with essential hypertension were also significantly lower than in normal subjects. Significant positive relations were found between urinary kallikrein and UV or UNaV in both hypertensive and normotensive groups, but there was no such correlation before fursemide administration. It is likely that diuresis and natriuresis induced by furosemide are somehow associated with an increase in urinary kallikrein excretion. Blunted response of urinary kallikrein in essential hypertension may suggest an abnormality in the renal kallikrein-kinin system in this disease.