title: Flow cytometric analysis of platelet activation in hypertensive patients. Effect of doxazosin.
abstract: The percentage of spontaneously activated platelets and the platelet response to several agonists were studied in 26 hypertensive patients. The percentage of platelets expressing glycoprotein (GP) IIb/IIIa in its active conformation (GPIIb/IIIa*), P-selectin and phosphatidylserine (PS) was measured by flow cytometry at baseline and 1 and 2 months after treatment with doxazosin (4 mg/day). The response to ADP and Ca2+ ionophore was also evaluated. The results were compared with those of a control group of 71 normotensive volunteers. Spontaneous platelet activation was higher in patients than in controls (P-selectin-positive results in 4.4+/-2.0% patients vs. 2.7+/-1.7 controls, p<0.05; phosphatidylserine-positive results in 0.7+/-0.4% vs. 0.5+/-0.3%, respectively, p<0.05), and higher in response to ionophore action (phosphatidylserine-positive results 51.8+/-11.1% vs. 43.4+/-11.7%, p<0.01). Platelet activation in patients decreased after 2 months of doxazosin administration compared to baseline (P-selectin-positive results 2.7+/-1.4% vs. 4.4+/-2.0%, p<0.05; phosphatidylserine-positive results 0.3+/-0.2% vs. 0.7+/-0.4%, p<0.05). No significant differences were noted in GPIIb/IIIa*. The clinical significance of normalization of platelet activity by doxazosin remains to be established.
mesh_terms: D000328:Adult; D000959:Antihypertensive Agents / Q000494:pharmacology*; D017292:Doxazosin / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects*
chemical_list: D000959:Antihypertensive Agents; D017292:Doxazosin