Modulation of pp60 super(c-src) tyrosine kinase activity during secretion in stimulated bovine adrenal chromaffin cells

To investigate the possible involvement of pp60 super(c-src) in exocytosis, cultured bovine chromaffin cells were analyzed for changes in c-src tyrosine kinase activity in response to stimulation by several secretagogues. pp60 super(c-src) derived from cells that had been stimulated for various lengths of time exhibited decreased auto- and transphosphorylating activities as compared to pp60 super(c-src) immunoprecipitated from control cells. The greatest reduction in activity was observed 10 min post-stimulation, while normal levels were regained 2-6 hr after secretagogue treatment. In experiments in which the rate of secretion of ( super(3)H)-norepinephrine from cells preloaded with this compound was compared to the rate of modulation of pp60 super(c-src) activity, 50% of the maximal reduction in pp60 super(c-src) activity occurred within 2-4 min while 50% maximal release of ( super(3)H)-norephinephrine occurred within 1-3 min. Taken together, these results suggest that pp60 super(c-src) may play some role (direct or indirect) in the exocytotic process.