Studies on renal and urinary kallikrein in spontaneously hypertensive rats.

Urinary kallikrein excretion, active (A) and total (T), was significantly reduced in the Okamato spontaneously hypertensive rat (SHR). The renal content of A and T soluble tissue kallikrein was clearly greater in this strain. Arginine vasopressin stimulated the release of both A and T kallikrein from renal cortical slices of the normotensive (N) Wistar strain, this response was not observed in the SHR. PGE2 stimulated release of A kallikrein in the N strain and both A and T enzyme in the SHR. It is suggested that urinary kallikrein excretion values may not necessarily reflect the endogenous levels of the enzyme in the kidney. Both the level and release of renal tissue kallikrein may become altered either in response to or as a result of chronically elevated blood pressure.