Toluene-induced, Ca(2+)-dependent vesicular catecholamine release in rat PC12 cells.

Acute effects of toluene on vesicular catecholamine release from intact PC12 phaeochromocytoma cells have been investigated using carbon fiber microelectrode amperometry. The frequency of vesicles released is low under basal conditions and is enhanced by depolarization. Toluene causes an increase in basal release frequency. The threshold effect is obtained at 30 microM toluene and the maximum enhancement of basal release is seven-fold at 1 mM toluene. Toluene-induced exocytosis depends on the influx of Ca(2+) through voltage-activated Ca(2+) channels, which are blocked by Cd(2+). Toluene neither affects depolarization-evoked exocytosis, nor the characteristics of release events. It is concluded that toluene-induced vesicular catecholamine release is due to an increase in intracellular Ca(2+) concentration, whereas basic processes underlying exocytosis do not appear to be affected by toluene at concentrations up to 300 microM.