Further characterization of dopamine release by permeabilized PC12 cells.
Rat pheochromocytoma cells (PC12) permeabilized with staphylococcal alpha-toxin release [3H]dopamine after addition of micromolar Ca2+. This does not require additional Mg2+-ATP (in contrast to bovine adrenal medullary chromaffin cells). We also observed Ca2+-dependent [3H]-dopamine release from digitonin-permeabilized PC12 cells. Permeabilization with alpha-toxin or digitonin and stimulation of the cells were done consecutively to wash out endogenous Mg2+-ATP. During permeabilization, ATP was removed effectively from the cytoplasm by both agents but the cells released [3H]dopamine in response to micromolar Ca2+ alone. Replacement by chloride of glutamate, which could sustain mitochondrial ATP production in permeabilized cells, does not significantly alter catecholamine release induced by Ca2+. However, Mg2+ without ATP augments the Ca2+-induced release. The release was unaltered by thiol-, hydroxyl-, or calmodulin-interfering substances. Thus Mg2+-ATP, calmodulin, or proteins containing -SH or -OH groups are not necessary for exocytosis in permeabilized PC12 cells.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000310:Adrenal Gland Neoplasms / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D002712:Chlorides; D003470:Culture Media; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D005971:Glutamates; D018698:Glutamic Acid; D010539:Permeability; D010673:Pheochromocytoma / Q000378:metabolism*; D051381:Rats; D014268:Trifluoperazine / Q000494:pharmacology
D002712:Chlorides; D003470:Culture Media; D005971:Glutamates; D014268:Trifluoperazine; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D004228:Dithionitrobenzoic Acid; D005033:Ethylmaleimide; D002118:Calcium; D004298:Dopamine