PLATELET ANGIOTENSIN-II BINDING-SITES IN NORMOTENSIVE AND HYPERTENSIVE WOMEN

Specific binding of angiotensin II (AII) to platelets was measured in 89 women, 25 nulliparous non-pregnant women and 64 primgravida in the third trimester of pregnancy. There was significantly lower binding in the 25 pregnant women who were normotensive (2.3 fmol/10(9) cells) when compared with the non-pregnant women (9.0 fmol/10(9) cells P < 0.001). Significantly higher platelet AII binding levels were found in the 39 women who had pregnancy induced hypertension (PIH) (5.5 fmol/10(9) cells) when compared with the 25 normotensive pregnant women (P < 0.001). Of the 39 women with PIH, platelet AII binding was higher in the 23 women who had pre-eclampsia (7.0 fmol/10(9) cells), when compared with the 16 who had non-proteinuric PIH, (4.6 fmol/10(9) cells) although the difference was not statistically significant (P < 0.04). The pressor response to AII is also diminished in pregnancy, yet less so if pregnancy induced hypertension develops. Platelets may provide a readily accessible tissue with which to study AII responsiveness in pregnancy.