目的:研究人血小板密度亚群在聚集和释放反应及细胞内钙浓度的异质性。方法:Percoll间断梯度离心法。结果:正常人血小板分为高(HD),中(ID)和低(LD)密度三个亚群。血小板的大小随密度的降低而减小(r=0.978,P<0.01)。HD对凝血酶(Thr),ADP和血清素(5-HT)诱导的聚集反应明显强于LD(P<0.01),ATP释放反应,除5-HT无ATP释放外,与聚集反应的结果一致。尽管细胞内游离钙([Ca~(2+)]_i的静息水平各亚群相同,但Thr,ADP和5-HT的[Ca~(2+)]_i动员仍以HD最为明显。结论:人HD血小板的功能及活性均高于LD血小板。 AIM: To study the heterogeneity of human platelet density subsets in aggregation and release responses and intracellular calcium concentration. Methods: Percoll discontinuous gradient centrifugation. Results: Normal human platelets were divided into three subgroups: high (HD), middle (ID) and low (LD) density. Platelet size decreased with decreasing density (r = 0.978, P <0.01). The aggregation of HD induced by thrombin (Thr), ADP and serotonin (5-HT) was significantly stronger than that of LD (P <0.01) and ATP release reaction, except for the release of 5-HT without ATP . Although resting levels of intracellular free calcium ([Ca ~ (2 +]] _i were the same for all subgroups, the mobilization of [Ca ~ (2 +)] _i for Thr, ADP and 5-HT was still most evident in HD. : Human HD platelets function and activity are higher than LD platelets.