ATP‐induced cation influx in myotubes is additive to cholinergic agonist action

HÄGGBLAD, J., ERIKSSON, H. & HEILBRONN, E. 1985. ATP‐induced cation influx in myotubes is additive to cholinergic agonist action. Acta Physiol Scand125, 389–393. Received 20 March 1985, accepted 1 May 1985. ISSN 0001–6772. Unit of Neurochemistry and Neurotoxicology, University of Stockholm, S‐172–46 Sundbyberg, Sweden. Using biochemical methods, ATP was shown to induce an inward flux of 86Rb into cultured chick myotubes. A biphasic dose‐response curve was observed, the first part of which was saturable and had an EC50 value of approximately 10 μM. β,γ‐imido ATP inhibited the ATP‐induced uptake. ADP, AMP and adenosine were less potent than ATP in producing influx. ATP‐induced influx of 86Rb was found to be additive to carbachol‐induced influx and, in contrast to the latter, not blocked by the nicotinic acetylcholine receptor antagonist α‐bungarotoxin. The results suggest the presence of an ATP recognition‐site on myotubes, triggering ion‐permeation.