辛伐他汀及oxLDL对人脐静脉内皮细胞蛋白激酶C活性和胞质内游离钙水平的影响

Effects of oxLDL and simvastatin on PKC activity and level of cytosolic free Ca^(2+) in cultured human umbilical vein endothelial cells

目的 :探讨氧化低密度脂蛋白 (ox L DL)及 3-羟基 - 3甲基戊二酰辅酶 A(HMG- Co A)还原酶抑制剂辛伐他汀对人脐静脉内皮细胞 (HU VEC)蛋白激酶 C(PKC)活性和胞质内游离钙浓度 ([Ca2 + ]i)的影响。 方法 :HUVEC的 PKC活性采用γ- 32 P- ATP磷酸转移法 ,细胞内游离钙采用 Fluo- 3/ Am荧光负载 ,流式细胞术检测。 结果 :ox L DL呈剂量依赖方式促进 HU -VEC PKC活性增加 ,12 min时达峰值 ,然后缓慢下降 ,30 m in时仍维持较高水平 ;胞质内 [Ca2 + ]i升高分快速相和持续相 2个时相 ;移去细胞外液钙 ,ox L DL仍引起快速相 ,但持续相消失 ;辛伐他汀则能明显抑制 ox L DL引起的 HU VEC PKC活性增加 ,并显著降低持续相胞质内钙水平 ,而对快速相无影响。 结论 :ox L DL能引起 HUVEC内信号通路 PKC及 [Ca2 + ]i的动态变化 ,二者密切相关。 ox L DL刺激 HUVEC [Ca2 + ]i升高的快速相是由胞质钙池释放引起 ,持续相升高主要由胞外钙内流引起。辛伐他汀抑制 HU VEC PKC活性可能是通过胞内 [Ca2 +

Objective: To investigate the effects of oxLDL and HMG CoA reductase inhibitor simvastatin on PKC activity, and level of cytosolic free Ca 2+ in cultured human umbilical vein endothelial cells. Methods: The activity of PKC was determined by its ability to transfer phosphate from 32 P ATP to lysine rich histone and level of cytosolic free calcium[Ca 2+ ]i was measured by flow cytometric analysis loading with the Ca 2+ dye Fluo 3/Am. Results: oxLDL increased PKC total activity in a dose dependent manner and peaked after 12 min, then decreased slowly and maintained for at least 30 min, while oxLDL induced biphasic [Ca 2+ ]i responses including the rapid initial transient phase and the sustained phase. Removal of extracellular Ca 2+ did not inhibit the rapid transient phase, but abolished the sustained phase. When simvastatin was added, the activity of PKC wasmarkedly decreased with no impairment to the initial peak response, but significantly reduced the sustained phase. Conclusion: oxLDL can induced dynamic changes of signal transduction of PKC and level of cytosolic free Ca 2+ in HUVEC, these 2 events are closely linked. The change of rapid initial transient phase is the result of mobilization of Ca 2+ from intracellular pool and the change of sustained phase is from the influx of extracellular Ca 2+ . The inhibition of PKC activity induced by simvastatin may contribute to the changes of [Ca 2+ ]i. [