出版社：American Society for Biochemistry and Molecular Biology
摘要：Lysophosphatidylcholine (lyso-PC) and arachidonate are products of phosphatidylcholine hydrolysis by phospholipase A2. In this study, the modulation of arachidonate release by exogenous lyso-PC in rat heart myoblastic H9c2 cells was examined. Incubation of H9c2 cells with lyso-PC resulted in an enhanced release of arachidonate in both a time- and dose-dependent fashion. Lyso-PC species containing palmitoyl (C16:0) or stearoyl (C18:0) groups evoked the highest amount of arachidonate release, while other lysophospholipid species were relatively ineffective. Cells treated with phospholipase A2 inhibitors resulted in the attenuation of the enhanced arachidonate release in the presence of lyso-PC. Lyso-PC caused the translocation of phospholipase A2 from the cytosol to the membrane fraction and induced an increase in Ca2+ flux from the medium into the cells. Nimodipine, a specific Ca2+-channel blocker, partially attenuated the lyso-PC-induced rise in intracellular Ca2+. Concurrent with Ca2+ influx, lyso-PC caused an enhancement of protein kinase C activity. The lyso-PC-induced arachidonate release was attenuated when cells were preincubated with specific protein kinase C and mitogen activated protein kinase kinase inhibitors. Taken together, these results strongly indicate that the lyso-PC-induced increases in levels of intracellular calcium and stimulation of protein kinase C lead to the activation of cytosolic phospholipase A2 which results in the enhancement of arachidonate release in H9c2 cells.— Golfman, L. S., N. J. Haughey, J. T. Wong, J. Y. Jiang, D. Lee, J. D. Geiger, and P. C. Choy. Lysophosphatidylcholine induces arachidonic acid release and calcium overload in cardiac myoblastic H9c2 cells. J. Lipid Res. 1999. 40: 1818–1826.
