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

Abstract

The role of phospholipase C (PLC) in exocytosis has been investigated using digitonin permeabilized, [ 3H]noradrenaline ([ 3H]NA) loaded, bovine adrenal medullary chromaffin cells. The PLC inhibitor U-73122 caused a concentration-dependent suppression of Ca 2+-evoked [ 3H]NA release but increased basal release (that occurring in the absence of Ca 2+). Preincubation with antibodies against PLCγ1 or PLCβ3 (but not PLCδ1, δ2, β1 and β2) also inhibited [ 3H]NA release evoked by Ca 2+ and increased basal release, indicating that only specific PLC isozymes are involved in these actions. Interestingly, PLCγ1 (but not PLCβ3) antibodies inhibited the ability of Ca 2+ to increase PLC activity in these permeabilized cells. These data therefore suggest that PLCγ1 activity may have a specific role in regulating the exocytotic response from the adrenal chromaffin cell.