氧化低密度脂蛋白及辛伐他汀对人单核细胞蛋白激酶C活性和胞浆内游离钙的影响

The effect of OX-LDL and simvastatin on PKC activity and cytosolic free Ca^(2+) in cultured human monocytes

目的探讨ＯＸ－ＬＤＬ及ＨＭＧ－ＣｏＡ还原酶抑制剂辛伐他汀对人单核细胞（Ｍｏ）表达蛋白激酶Ｃ（ＰＫＣ）活性和胞浆内游离钙（［Ｃａ２＋］ｉ）浓度的影响。方法Ｍｏ ＰＫＣ活性采用 γ－３２Ｐ－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－ＬＤＬ呈剂量依赖方式促进人 Ｍｏ ＰＫＣ活性增加，１２ ｍｉｎ时达峰值，然后缓慢下降，２０ ｍｉｎ后仍维持较高水平，胞浆内［Ｃａ２＋］ｉ升高分２个时相，即快速相和持续相。移去细胞外液钙，ＯＸ－ＬＤＬ仍引起快速相，但持续相消失，而辛伐他汀能明显抑制ＯＸ－ＬＤＬ．引起的Ｍｏ ＰＫＣ活性增加，并降低持续相胞浆内钙水平，而对快速相无明显影响。结论ＯＸ－ＬＤＬ能激活人单核细胞ＰＫＣ活性与升高［Ｃａ２＋］ｉ。ＯＸ－ ＬＤＬ刺激Ｍｏ［Ｃａ２＋］ｉ升高的快速相是有胞浆钙池释放引起，持续相升高主要有胞外钙内流引起。辛伐他汀抑制Ｍｏ ＰＫＣ活性可能是通过胞内钙水平变化起作用。

AIM To investigate the effect of OX- LDL and HMG-CoA reductase inhibitors simvastatin on PKC activity and cytosolic free Ca2+ in cultured human monocytes. METHOD The activity of PKC was determined by its ability to transfer phosphate fm [32P] ATP to lysine-rich histone and cytosolic free calcium[Ca2+]i was measured by flow cytometric analysis loading with the Ca2+ dye fluo3/Am.RE- SULTS OX-LDL increased PKC total activity in a dose-dependent manner with phase peaking at 12 min, then decreased slowly and maintained for at least 20 min, while OX-LDL induced biphasic [Ca2+ ], responses including the rapid initial transient phase and the sustained phase. Removal of extracellular Ca2+ did not inhibit the rapid initial transient phase of OX-LDL-induced rise. in [ Ca2+ ]i, but abol- abolished the sustained phase of [ Ca2+ ] i response to OX LDL. When simvastatin was added, the activity of PKC was markedly decreased and simvastatin did not impair the initial peak response to OX-LDL but sig- nificantly reduced the subsequent plateau phase. CONCLUSION OX-LDL can significantly activate the activity of PKC and elevate [Ca2+ ]i in monocytes. The rapid initial transient phase was the result of mobilization of [Ca2+ ], fm intracellular pool and sustained phase resulted from the influx of extracellular Ca2+. The inhibition of PKC activity induced by simvastatin may be contribute to the changes of intracellular Ca2+.