title: Capacitative calcium entry mechanism in porcine oocytes.
abstract: The presence of the capacitative Ca(2+) entry mechanism was investigated in porcine oocytes. In vitro-matured oocytes were treated with thapsigargin in Ca(2+)-free medium for 3 h to deplete intracellular calcium stores. After restoring extracellular calcium, a large calcium influx was measured by using the calcium indicator dye fura-2, indicating capacitative Ca(2+) entry. A similar divalent cation influx could also be detected with the Mn(2+)-quench technique after inositol 1,4,5-triphosphate-induced Ca(2+) release. In both cases, lanthanum, the Ca(2+) permeable channel inhibitor, completely blocked the influx caused by store depletion. Heterologous expression of Drosophila trp in porcine oocytes enhanced the thapsigargin-induced Ca(2+) influx. Polymerase chain reaction cloning using primers that were designed based on mouse and human trp sequences revealed that porcine oocytes contain a trp homologue. As in other cell types, the capacitative Ca(2+) entry mechanism might help in refilling the intracellular stores after the release of Ca(2+) from the stores. Further investigation is needed to determine whether the trp channel serves as the capacitative Ca(2+) entry pathway in porcine oocytes or is simply activated by the endogenous capacitative Ca(2+) entry mechanism and thus contributes to Ca(2+) influx.
authors.affiliation: Alexion Pharmaceuticals, Inc., Cheshire, Connecticut 06410, USA. machatyz@columbusfarming.com
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Macháty
authors.forename: Jagdeece J
authors.initials: JJ
authors.lastname: Ramsoondar
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Bonk
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Bondioli
authors.forename: Randall S
authors.initials: RS
authors.lastname: Prather
mesh_terms: D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics; D002413:Cations, Divalent; D004330:Drosophila / Q000235:genetics; D005260:Female; D005456:Fluorescent Dyes; D016257:Fura-2; D015870:Gene Expression; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D017385:Sequence Homology; D013552:Swine / Q000378:metabolism*; D050052:TRPC Cation Channels; D019284:Thapsigargin / Q000494:pharmacology; D014162:Transfection
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002413:Cations, Divalent; D005456:Fluorescent Dyes; D012333:RNA, Messenger; D050052:TRPC Cation Channels; D019284:Thapsigargin; D007811:Lanthanum; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium; D016257:Fura-2