Effect of low-dose aspirin on angiotensin II pressor response in human pregnancy.

Recent clinical studies have reported a significant reduction in the incidence of pregnancy-induced hypertension after the ingestion of low-dose aspirin. The effect of 80 mg of acetylsalicylic acid on vascular sensitivity to exogenous angiotensin II (Hypertensin, Ciba-Geigy Limited, Basel, Switzerland) was examined in 13 normotensive pregnant patients. The effective pressor dose before treatment (17.4 +/- 2.2 ng/kg/min) (mean +/- SE) was significantly less (p less than 0.001) than that after treatment (35.1 +/- 4.2 ng/kg/min). Low-dose aspirin therapy resulted in an enhancement of the pregnancy-acquired refractoriness to angiotensin II. It can be speculated that prostaglandin synthetase inhibitors at a low dose may alter the thromboxane A2/prostacyclin ratio in favor of the latter.