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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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CHO Cells / drug effects
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CHO Cells / metabolism*
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Calcium Channel Blockers / pharmacology
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Calcium Channels / drug effects
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Calcium Channels / metabolism*
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Calcium Signaling / drug effects
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Calcium Signaling / physiology*
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Carrier Proteins / metabolism
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Carrier Proteins / pharmacology
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Cricetinae
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Enzyme Inhibitors / pharmacology
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Intracellular Signaling Peptides and Proteins*
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Neuropeptides / metabolism
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Neuropeptides / pharmacology
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Orexin Receptors
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Orexins
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Receptors, G-Protein-Coupled
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Receptors, Neuropeptide / drug effects
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Receptors, Neuropeptide / metabolism*
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Thapsigargin / pharmacology
Substances
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Calcium Channel Blockers
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Calcium Channels
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Carrier Proteins
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Enzyme Inhibitors
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HCRT protein, human
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Intracellular Signaling Peptides and Proteins
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Neuropeptides
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Orexin Receptors
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Orexins
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Receptors, G-Protein-Coupled
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Receptors, Neuropeptide
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Thapsigargin