Role of PKCα–p38MAPK–Giα axis in NADPH oxidase derived -mediated activation of cPLA2 under U46619 stimulation in pulmonary artery smooth muscle cells

We have recently reported that treatment of bovine pulmonary artery smooth muscle cells with the thromboxane A2 mimetic, U46619 stimulated NADPH oxidase derived O 2 · - level, which subsequently caused marked increase in [Ca2+]i [17]. Herein, we demonstrated that O 2 · - -mediated increase in [Ca2+]i stimulates an aprotinin sensitive proteinase activity, which proteolytically activates PKC-α under U46619 treatment to the cells. The activated PKC-α then phosphorylates p38MAPK and that subsequently caused Giα phosphorylation leading to stimulation of cPLA2 activity in the cell membrane.