Effects of Severe Hypertension on Endothelial and Platelet Microparticles

The molecular mechanisms by which extreme blood pressure elevation leads to vascular injury are not defined. To explore the hypothesis that activation of endothelium and platelets as manifested by increased concentrations of circulating endothelial microparticles and platelet microparticles could play a role in this target organ injury, we conducted a cross-sectional study of these markers in 3 groups: (1) untreated patients referred specifically for treatment of severe uncontrolled hypertension; (2) untreated patients with established mild hypertension; and (3) normotensive volunteer subjects. By ANOVA, endothelial (P=0.002) and platelet (P=0.01) microparticles were greatest in the severely hypertensive group. There was a significant correlation between both of these markers and blood pressure, even in the setting of multiple risk factors. Our results suggest that these markers may be useful and specific for pressure-induced endothelial and platelet activation in hypertension. Furthermore, because of the combined effects of endothelial and platelet microparticles on coagulation, leukocytes, and endothelium, it is possible that they may play a pathogenic role in mediating target organ injury in severe hypertension.