The effect of OX-LDL and simvastatin on PKC activity and cytosolic free Ca 2+ in cultured human monocytes / 中国药理学通报

ABSTRACT

AIM　To investigate the effect of OX-LDL and HMG- CoA reductase inhibitors simvastatin on PKC activity and cytosolic free Ca2+ in cultured human monocy tes. METHOD　The activity of PKC was determined by its ability to tr ansfer phosphate from ［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. RESULTS　OX-LDL increased PKC tot al activity in a dose-dependent manner with phase peaking at 12 min, then decre ased slowly and maintained for at least 20 min, while OX-LDL induced biphasic ［Ca2+］i responses including the rapid initial transient phase and the sustained phase. Removal of extracellular Ca2+ did not inhibit the rapid i nitial transient phase of OX-LDL-induced rise in ［Ca2+］i,but abolish ed the sustained phase of ［Ca2+］i response to OX-LDL. When simvastati n was added, the activity of PKC was markedly decreased and simvastatin did not impair the initial peak response to OX-LDL but significantly reduced the subseq uent plateau phase. CONCLUSION OX-LDL can significantly activate t he activity of PKC and elevate ［Ca2+］i in monocytes. The rapid initial transient phase was the result of mobilization of ［Ca2+］i from intrac ellular pool and sustained phase resulted from the influx of extracellular Ca 2+. The inhibition of PKC activity induced by simvastatin may be contribute to the changes of intracellular Ca2+.