THE ROLE OF ANGIOTENSIN-II REGULATION OF GLOMERULAR-FILTRATION RATE DURING PREGNANCY

Objectives: This paper examines the effect of angiotensin-converting e nzyme (ACE) inhibition in the maintenance of glomerular filtration rat e during primate pregnancy. Study Design: Twenty timed mated pregnanci es were studied in 10 baboons receiving either enalapril 7.5 mg/day or placebo for each pregnancy in a prospective, randomized crossover des ign. Animals were studied nonpregnant, then at 8, 12, 16, 20, and 24 w eeks gestation. Tests included arterial pressure, plasma creatinine, s erum ACE activity, plasma electrolytes, plasma osmolality, hematocrit, and hemoglobin. Results: Serum ACE activity was significantly reduced for active versus placebo treatments (P < 0.001) throughout all phase s. Maternal mean arterial pressure was decreased by 8 weeks gestation in all animals, accompanied by significant fall in plasma sodium, plas ma potassium, and plasma osmolality (P < 0.01). In placebo-treated ani mals plasma creatinine fell significantly (P < 0.01) with pregnancy. A similar fall was also seen in active treated animals (P < 0.05).Concl usion: ACE inhibition had no deleterious effect on maternal renal func tion in pregnancy, despite decreased renal perfusion pressure. The res ult provides evidence that maintenance of glomerular filtration rate i n pregnancy is not angiotensin II dependent.