[Studies on the pathophysiology of pregnancy induced hypertension--endocrinological analysis by the method of angiotensin II and NaCl loading].

The responses of plasma renin activity (PRA), plasma bradykinin (BK) and urinary kallikrein like activity (UK) associated with the infusion of angiotensin II (AII) before and after NaCl loading were investigated in pregnancy induced hypertension (PIH). AII was infused step by step (2-10 ng/kg/min) into pregnant women (1st AII infusion). About 10 minutes later 100ml of physiological saline was rapidly infused, and the AII infusion was repeated (2nd AII infusion). PRA decreased dose dependently after the 1st AII infusion in normal pregnancy. But the decreasing pattern of PRA was not observed after the 2nd AII infusion in some cases of normal pregnancy, and was also not observed in many cases of PIH after the 1st or 2nd AII infusion. BK significantly increased after the 1st AII infusion and more remarkably after the 2nd AII infusion in normal pregnancy. In PIH, BK levels before the 1st AII infusion were higher than in normal pregnancy, but after the AII infusion increased less than in normal pregnancy. There was no difference between the rate of increase in UK output in normal pregnancy and in PIH. These data suggest that in PIH the mechanism for control of renin secretion is altered, and the vasodepressor system is stimulated in an in-situ condition, but its reserve function against the AII may be weaker than in normal pregnancy.