ABSTRACT
Much evidence suggests that platelets are involved in atherogenesis. Furthermore, it was postulated that intimal migration and proliferation of mooth muscle cells [SMC], partially responsible for the occlusive lesions of atherosclerosis, are affected by platelet-derived mitogens. In this study, the platelet mitogenic activity [PMA] of circulating platelets in patients with acute myocardial infraction [AMI] and unstable angina [UA] were investigated. Mean platelet volume [MPV], platelet count [PC] and PMA were studied within 24 hours of onset of chest pain. PMA was assesses by increased 3H-Labeled thymidine incorporation as an index for DNA synthesis of cultured aortic SMC after incubation with platelet-releasates. MPV was significantly increased in AMI [8.04 +/- 0.19 fl] compared with UA [6.53 +/- 0.06 fl; p 0.001]. PMA was increased by 2.3 fold in patients with AMI compared to those with UA. Also, PMA per unit platelet mass was increased in patients with AMI [20.85 +/- 2.52 cpm10/flx10-3] compared with UA group [9.04 +/- 1.28 cpm10/flx10-3; p 0.001]. Platelets from AMI patients appear to release more mitogenic factor [s] than those from UA. It is argued that circulating platelets may affect the progression of the underlying coronary atherosclerotic lesions and likely its sequelae