EVOKED ACETYLCHOLINE-RELEASE EXPRESSED IN NEUROBLASTOMA-CELLS BY TRANSFECTION OF MEDIATOPHORE CDNA

Transmitter release was elicited in two ways from cultured cells fille d with acetylcholine: (a) in a biochemical assay by successive additio n of a calcium ionophore and calcium and (b) electrophysiologically, b y electrical stimulation of individual cells and real-time recording w ith an embryonic Xenopus myocyte. Glioma C6-Bu-1 cells were found to b e competent for Ca2+-dependent and quantal release. In contrast, no re lease could be elicited from mouse neuroblastoma N18TG-2 cells. Howeve r, acetylcholine release could be restored when N18TG-2 cells were tra nsfected with a plasmid coding for mediatophore. Mediatophore is a pro tein of nerve terminal membranes purified from the Torpedo electric or gan on the basis of its acetylcholine-releasing capacity. The transfec ted N18TG-2 cells expressed Torpedo mediatophore in their plasma membr ane. In response to an electrical stimulus, they generated in the myoc yte evoked currents that were curare sensitive and calcium dependent a nd displayed discrete amplitude levels, like in naturally occurring sy napses.