Endothelin- and sarafotoxin-induced receptor-mediated calcium mobilization in a clonal murine osteoblast-like cell line, MC3T3-E1/B.
Previous studies have demonstrated that, in osteoblast-like MC3T3-E1 cells, various endothelin peptides and their homologous sarafotoxins generate prostaglandin E(2) (PGE(2)) release through an ET(A) receptor subtype. In this study, biphasic Ca(2+) signals elicited with endothelin (ET)-1, ET-2, ET-3, beta-ET, S6a1, and S6b (ET/S6) were measured by microspectrofluorimetric methods in cell suspensions loaded with Fura-2 acetoxymethylester (Fura-2 AM). Phospholipase C (PLC)-dependent calcium activation mechanisms seem to be involved. We found evidence of Ca(2+) release from thapsigargin-sensitive and non-thapsigargin-sensitive intracellular Ca(2+) stores as well as Ca(2+) transmembrane inflow through multiple voltage-independent and Ni(2+)-sensitive cation channels. Using an ET(A) receptor antagonist, BQ-123, we showed that this receptor was coupled to Ca(2+) mobilization. All agonists tested, except S6c (an ET(B)-receptor-specific agonist) induced receptor desensitization. Our results demonstrate that the ET/S6-induced Ca(2+) signaling pathway is mediated via an ET(A)-receptor subtype in MC3T3-E1/B cells.
Zach
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D
Department of Biochemical Analysis and Mass Spectrometry, University Children's Hospital, University of Graz, Graz, Austria. doris.zach@kfunigraz.ac.at
Windischhofer
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W
Leis
H J
HJ
D016475:3T3 Cells; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling; D003600:Cytosol / Q000378:metabolism; D016232:Endothelins / Q000494:pharmacology*; D004963:Estrenes / Q000494:pharmacology; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D014757:Viper Venoms / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D016232:Endothelins; D004963:Estrenes; D011760:Pyrrolidinones; D014757:Viper Venoms; C057354:sarafotoxins s6; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D010738:Type C Phospholipases; D002118:Calcium