Effects of Low-Dose Aspirin on Vascular Sensitivity to Angiotensin II and on 24 Hours Arterial Blood Pressure in Pregnancy

The angiotensin sensitivity test (AST) was performed in a group of 40 high risk pregnant women before and after oral administration of low doses of aspirin (ASA) (100 mg). AST performed before ASA characterized two groups of patients: 18 with positive AST (AST+) (effective pressor dose (EPD) = 6.91±1.69 (mean ± S.D.) ng/Kg/min of angiotensin II (A II)) and 22 with negative AST (AST-) (EPD = 22.44±11.23 ng/Kg/min of All). After ASA administration there was a significant increase in EPD in AST+ patients (15.00±9.54 ng/Kg/min, p<0.001). In AST- patients the mean EPD was significantly but non-homogeneously changed (18.33±8.11 ng/Kg/min). Nineteen pregnant high risk patients also underwent AST between weeks 24 and 39 of gestation. Then systolic, diastolic and mean arterial blood pressure were recorded using a portable device for indirect noninvasive automatic arterial pressure measure before and after seven days of low-dose aspirin therapy. In AST- patients no significant difference was observed before and after ASA regimen, whereas in AST+ patients post ASA mean blood pressure values were lower than pre ASA values, and during nighttime this difference became significant.