ATP depletion inhibits capacitative Ca2+ entry in rat thymic lymphocytes.
The present study investigates the requirement for cellular ATP in the increase in plasma membrane Ca2+ permeability activated by the release of Ca2+ from intracellular stores in rat thymic lymphocytes (capacitative Ca2+ entry). The permeability state of this pathway following activation with thapsigargin was probed in control and ATP-depleted cells using fluorometric measurements of intracellular Ca2+, Mn2+ entry, and membrane potential, and unidirectional measurements of Ca2+ uptake using 45Ca2+. The capacitative Ca(2+)-entry pathway was markedly inhibited in cells depleted of ATP by incubation in glucose-free solution containing oligomycin, antimycin A, and 2-deoxy-D-glucose. These data cannot be explained on the basis of a loss of the transmembrane electrochemical gradient for Ca2+, alterations in intracellular pH or cellular Na+ content, a direct effect of the inhibitors of ATP production on the capacitative Ca(2+)-entry pathway, or the ability of thapsigargin to release Ca2+ from intracellular stores. Rather, these data are consistent with a requirement for ATP or a high-energy phosphate donor in the activation and/or maintained activation of capacitative Ca2+ entry.
Marriott
I
I
Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA.
Mason
M J
MJ
D000255:Adenosine Triphosphate / Q000172:deficiency*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D005470:Fluorometry; D007425:Intracellular Membranes / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008345:Manganese / Q000378:metabolism; D008564:Membrane Potentials; D051381:Rats; D017208:Rats, Wistar; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism*
D013729:Terpenes; D008345:Manganese; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D002118:Calcium