Effects of short- and long-term exposure to linoleic acid hydroperoxide on cytosolic calcium ion level of human aortic intimal smooth muscle cells in vitro.

When cultured intimal smooth muscle cells from human aorta were exposed for a short period of time (25 sec) to linoleic acid hydroperoxide (100 nmol/ml), influx of calcium ions into the cytosol of these cells was provoked, and a temporal increase in cytosolic calcium ion level was observed. Two calcium channel blockers inhibited this influx. Long-term exposure (4 min) of these cells to the hydroperoxide also provoked the influx of calcium ions, which resulted in a longer time of the calcium ion increase. In the latter case, however, the calcium channel blocker inhibited the initial influx, but then the influx started and continued even in the presence of the blocker. Such difference in exposure time-dependent effects should be taken into account in considering pathological roles of lipid hydroperoxides.