Urinary kallikrein activity in pregnant hypertensive rats

Goldblatt one-kidney one-clip (G1K-1C) hypertensive rats were studied to determine the changes of blood pressure (BP) and urinary kallikrein (UK) excretion throughout pregnancy. Uninephrectomized rats (Unx) were used as controls. Both groups showed a significant decrease in BP on day 21 of pregnancy, although G1K-1C rats had higher values. UK activity was markedly stimulated in both groups, reaching its highest level on day 21. This increment in UK was due to greater delivery and/or synthesis of the enzyme, since no change was observed in the active fraction. We postulate that the highly activated kallikrein-kinin system might be contributing to the hypotensive effect of pregnancy.