Decreased urinary kallikrein activity and elevated blood pressure normalized by orally applied kallikrein in essential hypertension.

Urinary kallikrein excretion was significantly lower in patients with essential hypertension (0.48 +/- 0.05 EU/24 h) than in normotensive controls (1.26 +/- 0.14 EU/24 h). Oral administration of hog pancreatic kallikrein normalized decreased urinary kallikrein and reduced arterial pressure. The treatment-induced rise in urinary kallikrein was due to an enhanced release of endogenous enzyme, as was determined by radioimmunoassay. It is proposed that in the hypertensive patients the low urinary kallikrein excretion reflects a defect in renal kallikrein formation which is normalized by oral kallikrein. The hypotensive action of oral kallikrein as well as its stimulating effects on renal kallikrein release suggest that the kallikrein-kinin system is involved in blood pressure regulation and that impaired renal kallikrein activity may be a factor in the maintenance of essential hypertension.