Platelet Alpha-2 Receptors in Normotensive and Hypertensive Pregnancies in Blacks

It is known that hypertension among blacks starts at earlier ages and has a higher mortality rate as compared to other populations. Alpha-2 receptors were compared in the platelets of normotensive (n=19) and hypertensive pregnant black women (n=29). Characterization and identification of alpha-2 receptors were performed by radio receptor assay. Platelet membranes were incubated with various concentrations of [3H]yohimbine as an alpha-2 antagonist. The maximum number of binding sites (Bmax) and dissociation constant (Kd) were determined by Scatchard analysis. The maximum number of binding sites were 331 fM/mg (normotensive n=19), 286 fM/mg (chronic hypertension n=12), and 357 fM/mg (preeclampsia n=17). These values were not statistically significant. Conclusions: alpha-2 platelet receptors are not altered in hypertensive pregnancies.