VINBLASTINE ENHANCEMENT OF HYPOSMOSIS-INDUCED CATECHOLAMINE RELEASE IN CULTURED ADRENAL CHROMAFFIN CELLS - LACK OF RELATION TO CELL SWELLING AND MICROTUBULE DISRUPTION

Exposure of chromaffin cells to hyposmotic solution has been shown to cause catecholamine release through the elevation of intracellular Ca2 + level. While cell volume change observed under hyposmotic conditions has been shown to be accompanied by the movement of various ions and suggested to be associated with the reorganization of cytoskeletons. I n the present study, the effects of cytoskeleton-disrupting agents on hyposmosis-induced catecholamine release were examined to investigate a possible relationship between catecholamine release and cell volume change under hyposmotic conditions. Hyposmosis-induced catecholamine r elease was enhanced by pre-treatment of the cells with a microtubule-d isrupting agent vinblastine, but not significantly altered by a microf ilament-disrupting agent cytochalasin B. Vinblastine also caused an ad ditional increase in the intracellular Ca2+, but failed to affect the cell volume change under hyposmotic conditions. In contrast, the hypos mosis-induced release was not significantly altered by either colchici ne, another microtubule-disrupting agent, or taxol, a microtubule-stab ilizing agent. These results indicate that vinblastine enhances hyposm osis-induced catecholamine release through an additional increase in t he intracellular Ca2+ and furthermore suggest that this effect of vinb lastine on the hyposmosis-induced release is unassociated with the dis ruption of the microtubule system, providing evidence for a lack of th e direct relationship between catecholamine release and, the cell volu me change observed under hyposmotic conditions. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.