Effect of Oral Contraceptive Therapy on the Renin-Angiotensin System in Normotensive and Hypertensive Women

Plasma renin activity, plasma renin substrate, angiotensin I, and plasma angiotensinase activity were measured in 13 women, of whom 5 were normotensive during oral contraceptive therapy (OCT) and 8 became hypertensive during such therapy. In one 21-day cycle of OCT. the mean plasma renin activity increased by two-thirds and the plasma renin substrate more than doubled in both groups of women. The mean angiotensin I increased in both groups— by about two-thirds in the normotensives, and by not quite one-half in the hypertensives. The mean plasma angiotensinase activity increased by one-half among the normotensives; in contrast, it decreased slightly among the hypertensives, only 2 of whom showed increases. Our findings agree with the hypothesis that abnormal inactivation of angiotensin II may have an important influence on the pathogenesis of arterial hypertension complicating oral contraceptive therapy.