INTERACTIONS OF Na+, H2O2 AND THE Na+-Ca2+ EXCHANGER STIMULATE Ca2+ RELEASE IN CK1.4 CELLS |
| |
Authors: | Yan Fang Mingyang Rong Lianfang He |
| |
Institution: | *Department of Anesthesiology, Shanghai, China, Shanghai Medical University, Shanghai, China;?Medical Instrumentation Institute and Shanghai, China, Shanghai Medical University, Shanghai, China;?State Laboratory of Medical Neurobiology, Shanghai Medical University, Shanghai, China |
| |
Abstract: | 1. The present study aimed to demonstrate that interactions 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 22 and 23 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 CI cells, an elevated 45Ca2+] uptake was induced by Ca2+, Na+ and H2O2 individually and in combination, intracellular 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-π interaction (a strong non-covalent force between the cation and the π 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. |
| |
Keywords: | calcium metabolism cations free radicals membrane protein physiology |
|
|