title: Interactions of Na+, H2O2 and the Na+-Ca2+ exchanger stimulate Ca2+ release in CK1.4 cells.
abstract: 1. The present study aimed to demonstrate that interaction of cations, hydrogen peroxide (H2O2) and the Na(+)-Ca2+ exchanger stimulate Ca2+ release and oscillations of cytosolic Ca2+[Ca2+]i in non-transfected Chinese Hamster Ovary (CHO) C1 cells and in transfected CHO (CK1.4) cells that contained an expression vector coding the Na(+)-Ca2+ exchanger sequence. 2. The [45Ca2+] uptake assay, fura-2 fluorescence imaging and 2(2) and 2(3) factorial orthogonal statistics provide comparative, direct, efficient, quantitative and transient methods to delineate the effects of such interactions on Ca2+ influx, Ca2+ release and [Ca2+]i in C1 and CK1.4 cells. 3. In contrast to the control of either Na(+)-, Ca2(+)- or H2O2-free or C1 cells, an elevated [45Ca2+] uptake was induced by Ca2+, Na+ and H2O2 individually and in combination, intra-cellular Ca2+ release was activated by H2O2, and by combinations of either H2O2 and Na+, H2O2 and the Na(+)-Ca2+ exchanger, Na+ and the Na(+)-Ca2+ exchanger or by H2O2, Na+ and the Na(+)-Ca2+ exchanger and a rise in [Ca2+]i was triggered by H2O2, Na+ and a combination of Na+ and the Na(+)-Ca2+ exchanger. 4. These results indicate that interactions between H2O2, Na+ and the Na(+)-Ca2+ exchanger stimulate intracellular Ca2+ mobilization via Ca2(+)-induced Ca2+ release mechanisms, ATP-activated G-protein coupled P2y-purinoceptor-sensitive pathways, Na(+)-Ca2+ exchanger-mediated Ca2+ influx and cation-pi interaction (a strong non-covalent force between the cation and the pi face of an aromatic structure in the transmembrane protein). 5. The present findings provide important clues for understanding Ca2+ signal transduction mechanisms from the plasma membrane to the endoplasmic reticulum.
authors.affiliation: Department of Anesthesiology, Shanghai Medical University, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Fang
authors.forename: M
authors.initials: M
authors.lastname: Rong
authors.forename: L
authors.initials: L
authors.lastname: He
mesh_terms: D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000494:pharmacology*; D006224:Cricetinae; D004357:Drug Synergism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology*; D019831:Sodium-Calcium Exchanger; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D019831:Sodium-Calcium Exchanger; D012964:Sodium; D006861:Hydrogen Peroxide; D002118:Calcium