The involvement of specific phospholipase C isozymes in catecholamine release from digitonin permeabilized bovine adrenal medullary chromaffin cells

The role of phospholipase C (PLC) in exocytosis has been investigated using digitonin permeabilized, [H-3]noradrenaline ([H-3]NA) loaded, bovine adrenal medullary chromaffin cells. The PLC inhibitor U-73122 caused a concentration-dependent suppression of Ca2+-evoked [H-3]NA release but increased basal release (that occurring in the absence of Ca2+). Preincubation with antibodies against PLCgammal or PLCbeta3 (but not PLCdelta1 delta2, beta1 and beta2) also inhibited [H-3]NA release evoked by Ca2+ and increased basal release, indicating that only specific PLC isozymes are involved in these actions. Interestingly, PLCgamma1 (but not PLCbeta3) antibodies inhibited the ability of Ca2+ to increase PLC activity in these permeabilized cells. These data therefore suggest that PLCgamma1 activity may have a specific role in regulating the exocytotic response from the adrenal chromaffin cell. (C) 2003 Elsevier Science Ireland Ltd. All fights reserved.