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Updated: Aug 14, 2026

Fluorescence-based Measurement of Store-operated Calcium Entry in Live Cells: from Cultured Cancer Cell to Skeletal Muscle Fiber
Published on: February 13, 2012
Orexin receptors couple to Ca2+ channels different from store-operated Ca2+ channels
1Department of Physiology, Division of Cell Physiology, Uppsala University, BMC, P.O. Box 572, SE-75123 Uppsala, Sweden.
Abstract:
We have investigated Ca2+ release and receptor- and store-operated Ca2+ influxes in Chinese hamster ovary-K1 cells expressing human OX1 orexin receptor. Receptor-operated Ca2+ influx-response to 3 nM orexin-A was not affected by Gd3+ or 2-APB (2-aminoethoxydiphenyl borate), but was inhibited by Ni2+. Store-operated Ca2+ influx was blocked by Ni2+, Gd3+ and 2-APB, whereas the thapsigargin-induced release was unaffected. 2-APB did not block inositol-1,4,5- trisphosphate-dependent Ca2+ release in these cells. Thus, low concentrations of orexin-A cause activation of two Ca2+ influxes in the cells: primarily, a receptor-operated Ca2+ influx, and secondarily, a store-depletion activated Ca2+ influx, which is subsequent to receptor-activated Ca2+ influx and the therewith-caused IP3 production. The results show that these two rely on different molecular entities.
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