Abstract
The role of ATP in both the activation of store-operated Ca2+ current I CRAC and in Ca2+-dependent vesicular fusion was examined in a study of rat basophilic leukaemia (RBL) cells using the whole-cell patch-clamp technique. Fusion was monitored via changes in plasma membrane capacitance. Following a decrease in the levels of intracellular ATP, achieved using the mitochondrial poison antimycin and the ATP synthase inhibitor oligomycin, as well as a reduction of glycolysis by removal of external glucose, I CRAC activated in a manner similar to control cells when stores are depleted by dialysis with a pipette solution containing either inositol 1,4,5-trisphosphate (InsP 3) or ionomycin together with a high concentration of EGTA. Dialysis of cells for 150 s with the non-hydrolysable ATP analogue 5′-adenylylimidodiphosphate (AMP-PNP) (2 mM) in addition to the mitochondrial inhibitors also failed to prevent activation of I CRAC following external application of ionomycin and thapsigargin, when compared with control recordings obtained with 2 mM ATP instead. Ca2+-dependent vesicular fusion was triggered by dialysing cells with 10 µM Ca2+ and guanosine-5′-O-(3-thiotriphosphate (GTP[γ-S]). The capacitance increase was unaffected by inhibition of glycolysis, mitochondrial inhibitors or dialysis with either AMP-PNP or adenosine 5′-O-(3-thiotriphosphate) (ATP[γ-S]) instead of ATP. We conclude that ATP hydrolysis does not seem to be necessary for the activation of I CRAC or for the capacitance increases elicited by high concentrations of intracellular Ca2+.
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Received: 1 May 1998 / Received after revision: 16 July 1998 / Accepted: 16 July 1998
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Scott, S., Kiessling, K. & Parekh, A. An examination of the role of intracellular ATP in the activation of store-operated Ca2+ influx and Ca2+-dependent capacitance increases in rat basophilic leukaemia cells. Pflügers Arch 436, 928–933 (1998). https://doi.org/10.1007/s004240050725
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DOI: https://doi.org/10.1007/s004240050725