Yamagishi S I, Edelstein D, Du X L, Brownlee M
Department of Medicine, Diabetes Research Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Diabetes. 2001 Jun;50(6):1491-4. doi: 10.2337/diabetes.50.6.1491.
Alteration of platelet function contributes to microthrombus formation and may play an important role in the pathogenesis of diabetic micro- and macroangiopathies. However, the molecular mechanism for platelet dysfunction observed in patients with diabetes has not been fully elucidated. In this study, the direct effects of hyperglycemia on platelet function in vitro were investigated. Hyperglycemia increased reactive oxygen species generation in human platelets, and this effect was additive with that of collagen. Thenoyltrifluoroacetone (TTFA), an inhibitor of mitochondrial electron transport chain complex II, and carbonyl cyanide m-chlorophenylhydrazone (CCCP), an uncoupler of oxidative phosphorylation, completely prevented the effects of hyperglycemia, suggesting that reactive oxygen species arise from the mitochondrial electron transport chain. Hyperglycemia potentiated both platelet aggregation and the subsequent release of platelet-derived growth factor AB induced by a nonaggregating subthreshold concentration of collagen, which were also completely inhibited by TTFA or CCCP. Furthermore, hyperglycemia was found to inhibit protein tyrosine phosphatase (PTP) activity and increase phosphorylation of the tyrosine kinase Syk in platelets exposed to collagen. Hyperglycemia-induced PTP inhibition and Syk phosphorylation were found to be completely prevented by TTFA, CCCP, or Mn(III)tetrakis (4-benzoic acid) porphyrin, a stable cell-permeable superoxide dismutase mimetic. These results suggest that hyperglycemia-induced mitochondrial superoxide generation may play an important role in platelet dysfunction observed in patients with diabetes.
血小板功能的改变有助于微血栓形成，并且可能在糖尿病微血管和大血管病变的发病机制中发挥重要作用。然而，糖尿病患者中观察到的血小板功能障碍的分子机制尚未完全阐明。在本研究中，我们研究了高血糖对体外血小板功能的直接影响。高血糖增加了人类血小板中活性氧的生成，并且这种作用与胶原蛋白的作用相加。线粒体电子传递链复合物II的抑制剂噻吩甲酰三氟丙酮（TTFA）和氧化磷酸化解偶联剂羰基氰化物间氯苯腙（CCCP）完全阻止了高血糖的作用，表明活性氧来自线粒体电子传递链。高血糖增强了由非聚集性亚阈值浓度胶原蛋白诱导的血小板聚集以及随后血小板衍生生长因子AB的释放，这也被TTFA或CCCP完全抑制。此外，发现高血糖会抑制暴露于胶原蛋白的血小板中的蛋白酪氨酸磷酸酶（PTP）活性并增加酪氨酸激酶Syk的磷酸化。发现TTFA、CCCP或锰（III）四（4-苯甲酸）卟啉（一种稳定的细胞可渗透超氧化物歧化酶模拟物）可完全阻止高血糖诱导的PTP抑制和Syk磷酸化。这些结果表明，高血糖诱导的线粒体超氧化物生成可能在糖尿病患者中观察到的血小板功能障碍中起重要作用。
