Cooling sensitive [Ca2+]i response associated with signaling of G protein-coupled receptors.
The influence of cooling on the intracellular concentration of Ca2+ ([Ca2+]i) was tested in cell lines expressing chemical receptors. First, when ATP was externally added to rat basophilic leukemia (RBL-2H3) cells, cooling from 37 degrees C to 27 degrees C induced a transient rapid increase in [Ca2+]i. In the absence of extracellular Ca2+, the [Ca2+]i response was induced whereas an inhibitor of microsomal Ca2+ ATPase, thapsigargin, largely abolished the [Ca2+]i response, suggesting that the internal Ca2+ store liberate the Ca2+. A purinergic receptor antagonist, suramin, completely inhibited the [Ca2+]i response to the cooling. Secondly, when serotonin (5-HT) was added to rat glioma C6BU-1 cells, the cooling induced a transient increase in [Ca2+]. This [Ca2+]i response was induced in the absence of external Ca2+, suggesting that the internal Ca2+ stores liberate the Ca2+. These results raise the possibility that some G protein-coupled receptors are sensitive to cooling in the presence of agonist for the receptor.
Division of Biophysical Engineering, Graduate School of Engineering Science, Osaka University, Japan.
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Nagai
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Nakaoka
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D003080:Cold Temperature; D005456:Fluorescent Dyes; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005910:Glioma; D007700:Kinetics; D015471:Leukemia, Basophilic, Acute; D008861:Microsomes / Q000201:enzymology; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology; D013498:Suramin / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014966:Xanthenes
D000814:Aniline Compounds; D005456:Fluorescent Dyes; D011956:Receptors, Cell Surface; D014966:Xanthenes; C059715:Fluo-3; D012701:Serotonin; D013498:Suramin; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins; D000252:Calcium-Transporting ATPases; D002118:Calcium