PLATELET AGGREGABLLITY AND METABOLISM IN PATIENTS WITH UNSTABLE ANGINA PECTORIS

Abstract

Several platelet products indicating platelet activation have been detected in blood and urine of patients (PTS) with angina pectoris (AP) at rest. Platelet activation mainly depends on local changes in the morphology or biochemical behaviour of the vessels. Whether platelet hyperaggregability is of additional importance in the pathogenesis of unstable AP is up to now unclear. In a prospective trial we therefore evaluated 32 patients (PTS) with coronary heart disease, 16 with AP at rest during the last 8 hours before blood collection and 16 age and sex matched controls with stable exertional AP. Platelet aggregation was measured upon stimulation with ADP (0.5, 1 and 10 μmol/l) and collagen (1and 5μg/ml), and c-AMP was determined in platelet rich plasma before, and, as an estimate of platelet adenylate cyclase activity, after stimulation of this enzyme with PGE 1 (10 μmol/l for 30 s). For all concentrations of both ADP and collagen no significant differences in the rates and extents of aggregation could be found between the groups. Correspondingly, the mean (±. 2 SEM) concentrations of c-AMP were similar, basally (4.1 ±.1.4 pmol/ml for PTS withunstable AP and 5.3 t 1.3 pmol/ml for PTS with stable AP)and after stimulation of platelet adenylate cyclase with PGE 1 (14.8 ± 4.1 vs. 17.2 ± 2.8 pmol/ml).Conclusion: No generalized platelet hyperaggregability could be detected in our PTS with unstable AP when compared to controls with stable exertional AP.