目的　观察脑梗死病人急性期血小板密度、细胞内游离钙浓度及血小板聚集和释放的变化。方法　以梯度离心法制备血小板密度亚群 ,激光共聚焦显微镜法测定Fluo- 3/AM负载后血小板细胞内游离钙荧光强度的变化 ,以透光度法和介质中ATP的量评价血小板的凝集和释放反映。对照组和实验组血小板分别来自于正常志愿者和脑梗死病人急性期的静脉血。结果　①Percoll梯度离心的结果表明 ,脑梗死病人急性期血液中高密度亚群 (比重 >1 0 6 2 )血小板的数量与对照组〔(2 4 6± 8 6 ) % ,n =5〕比较显著增多〔(5 2 1± 11 4) % ,n =6 ,P <0 0 0 1〕 ,上述结果与共聚焦显微镜直接观察的结果一致。②与对照组相比 3μΜADP介导的聚集反应增强〔(6 9 4± 19 8) % ,P <0 0 1〕 ,介质中ATP的含量为 1 2 6± 0 44 (P <0 0 1)。③对照组和实验组细胞内钙的静息水平无明显差异 ,加 10 μΜADP后 ,实验组细胞内钙的荧光强度增加明显 (86 2± 319,P <0 0 1)。结论　与对照组比较 ,脑梗死病人急性期 ,高密度亚群血小板的数量显著增加。血小板聚集和释放功能明显增强 ,这一结果可能与细胞游离钙增加有关。 Objective To observe the changes of platelet density, intracellular free calcium concentration and platelet aggregation and release in acute cerebral infarction patients. Methods The density of platelet densities were prepared by gradient centrifugation. The change of intracellular free calcium fluorescence intensity after Fluo-3 / AM loading was measured by confocal laser scanning microscopy. The platelet aggregation and platelet count Release reflect. Control and experimental platelets were from normal volunteers and patients with acute cerebral infarction venous blood. Results ① The results of Percoll gradient centrifugation showed that the number of high density subpopulations of blood (> 1066) in the acute phase of cerebral infarction patients was significantly increased compared with that of the control group [(24 6 ± 86)%, n = 5] 〔(5 2 1 ± 11 4)%, n = 6, P <0 0 0 1〕. The above results are consistent with the results of direct observation by confocal microscopy. ② Compared with the control group, 3μM ADP-mediated aggregation increased [(69.4 ± 19.8)%, P <0.01), and the content of ATP in the medium was 126 ± 0 44 (P <0.01) . ③ There was no significant difference in intracellular calcium resting between the control group and the experimental group. After addition of 10 μM ADP, the intracellular calcium fluorescence intensity of the experimental group increased significantly (86 2 ± 319, P <0.01). Conclusions Compared with the control group, the number of platelets in high density subgroups in acute phase of cerebral infarction is significantly increased. Platelet aggregation and release of significantly enhanced, this result may be related to increased cell free calcium.