The Role of Angiotensin II Regulation of Glomerular Filtration Rate During Pregnancy

Abstract

Objectives: This paper examines the effect of angiotensin-converting enzyme (ACE) inhibition in the maintenance of glomerular filtration rate during primate pregnancy.

Study Design: Twenty timed mated pregnancies were studied in 10 baboons receiving either enalapril 7.5 mg/day or placebo for each pregnancy in a prospective, randomized crossover design. Animals were studied nonpregnant, then at 8, 12, 16, 20, and 24 weeks gestation. Tests included arterial pressure, plasma creatinine, serum 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 phases. Maternal mean arterial pressure was decreased by 8 weeks gestation in all animals, accompanied by significant fall in plasma sodium, plasma potassium, and plasma osmolality (P< 0.01). In placebo-treated animals plasma creatinine fell significantly (P < 0.01) with pregnancy. A similar fall was also seen in active treated animals (P < 0.05).

Conclusion: ACE inhibition had no deleterious effect on maternal renal function in pregnancy, despite decreased renal perfusion pressure. The result provides evidence that maintenance of glomerular filtration rate in pregnancy is not angiotensin II dependent.

Key Words:

• Angiotensin-converting enzyme
• Papio hamadryas
• Primate
• Renal function