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+.
ABSTRACT
Objective: To investigate the effects of oxLDL and HMG-CoA reductase inhibitor simvastatin on PKC activity, and level of cytosol ic free Ca 2+ in cultured human umbilical vein endothelial cells. Methods: Th e activity of PKC was determined by its ability to transfer phosphate from 32P-ATP to lysine-rich histone and level of cytosolic free calcium［Ca2+ ］i was measured by flow cytometric analysis loading with the Ca2+ dye F luo-3/Am. Results: oxLDL increased PKC total activity in a dose-de pendent manner and peaked after 12 min, then decreased slowly and maintained for at least 30 min, while oxLDL induced biphasic ［Ca2+］i responses includ ing the rapid initial transient phase and the sustained phase. Removal of extrac ellular Ca2+ did not inhibit the rapid transient phase, but abolished the sustained phase. When simvastatin was added, the activity of PKC wasmarkedly dec reased with no impairment to the initial peak response, but significantly reduce d the sustained phase. Conclusion: oxLDL can induced dynamic changes of signal transduction of PKC and level of cytosolic free Ca2+ in HUVEC, these 2 events are closely linked. The change of rapid initial transient phase i s the result of mobilization of Ca2+ from intracellular pool and the chang e of sustained phase is from the influx of extracellular Ca2+. The inhibit ion of PKC activity induced by simvastatin may contribute to the changes of ［Ca 2+］i.
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 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+.
ABSTRACT
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. [