Orexin receptors couple to Ca2+ channels different from store-operated Ca2+ channels

Neuroreport. 2001 Jul 3;12(9):2017-20. doi: 10.1097/00001756-200107030-00046.


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

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells / drug effects
  • CHO Cells / metabolism*
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / drug effects
  • Calcium Channels / metabolism*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Carrier Proteins / metabolism
  • Carrier Proteins / pharmacology
  • Cricetinae
  • Enzyme Inhibitors / pharmacology
  • Intracellular Signaling Peptides and Proteins*
  • Neuropeptides / metabolism
  • Neuropeptides / pharmacology
  • Orexin Receptors
  • Orexins
  • Receptors, G-Protein-Coupled
  • Receptors, Neuropeptide / drug effects
  • Receptors, Neuropeptide / metabolism*
  • Thapsigargin / pharmacology


  • Calcium Channel Blockers
  • Calcium Channels
  • Carrier Proteins
  • Enzyme Inhibitors
  • HCRT protein, human
  • Intracellular Signaling Peptides and Proteins
  • Neuropeptides
  • Orexin Receptors
  • Orexins
  • Receptors, G-Protein-Coupled
  • Receptors, Neuropeptide
  • Thapsigargin