Extracellularly applied ATP alters the calcium flux through dihydropyridine-sensitive channels in cultured chick myotubes.
Extracellularly applied ATP mediates a biphasic calcium signal in cultured chick myotubes. A rapid and transient increase in cytosolic calcium was independent of extracellular calcium while a second signal, slower in onset and decay, was absent without extracellular calcium. In depolarized myotubes, the cytosolic [Ca2+] was increased more than ten times above baseline level. Addition of ATP to the incubation medium immediately increased the rate of return of cytosolic Ca2+ levels to baseline. The ATP effect was half-maximal at about 10 microM ATP and was mimicked by ATP S. This ATP-sensitive calcium influx was also rapidly stopped by addition of dihydropyridines such as PN 200-110, suggesting that it is the voltage operated Ca2+-channel that was inactivated by ATP.
Eriksson
H
H
Unit of Neurochemistry and Neurotoxicology, University of Stockholm, Sweden.
Heilbronn
E
E
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002645:Chickens; D003600:Cytosol / Q000378:metabolism; D004095:Dihydropyridines / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D007700:Kinetics; D009132:Muscles / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; D004095:Dihydropyridines; C022571:adenosine 5'-O-(3-thiotriphosphate); D004533:Egtazic Acid; C038806:1,4-dihydropyridine; D000255:Adenosine Triphosphate; D002118:Calcium