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 < 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 prostglandin synthetase inhibitors at a low dose may alter the thromboxane A₂/prostacyclin ratio in favor of the latter.