Regulation of Na + /Ca 2+ exchange activity by cytosolic Ca 2+ in transfected Chinese hamster ovary cells

Transfected Chinese hamster ovary cells stably expressing the bovine cardiac Na + /Ca 2+ exchanger (CK1.4 cells) were used to determine the range of cytosolic Ca 2+ concentrations ([Ca 2+ ] i ) that activate Na + /Ca 2+ exchange activity. Ba 2+ influx was measured in fura 2-loaded, ionomycin-treated cells under conditions in which the intracellular Na + concentration was clamped with gramicidin at ∼20 mM. [Ca 2+ ] i was varied by preincubating ionomycin-treated cells with either the acetoxymethyl ester of EGTA or medium containing 0–1 mM added CaCl 2 . The rate of Ba 2+ influx increased in a saturable manner with [Ca 2+ ] i , with the half-maximal activation value of 44 nM and a Hill coefficient of 1.6. When identical experiments were carried out with cells expressing a Ca 2+ -insensitive mutant of the exchanger, Ba 2+ influx did not vary with [Ca 2+ ] i . The concentration for activation of exchange activity was similar to that reported for whole cardiac myocytes but approximately an order of magnitude lower than that reported for excised, giant patches. The reason for the difference in Ca 2+ regulation between whole cells and membrane patches is unknown.

[1]  C. Dyck,et al.  Transport and Regulation of the Cardiac Na+-Ca2+ Exchanger, NCX1 , 1997, The Journal of general physiology.

[2]  J. Reeves,et al.  Barium Influx Mediated by the Cardiac Sodium-Calcium Exchanger in Transfected Chinese Hamster Ovary Cells , 1997, The Journal of general physiology.

[3]  Yu Fang,et al.  Acceleration of Sodium-Calcium Exchange Activity during ATP-induced Calcium Release in Transfected Chinese Hamster Ovary Cells , 1997, The Journal of general physiology.

[4]  M. Kappl,et al.  Rapid charge translocation by the cardiac Na(+)-Ca2+ exchanger after a Ca2+ concentration jump. , 1996, Biophysical journal.

[5]  D. Hilgemann,et al.  Regulation of Cardiac Na+,Ca2+ Exchange and KATP Potassium Channels by PIP2 , 1996, Science.

[6]  D. Hilgemann.  Unitary cardiac Na+, Ca2+ exchange current magnitudes determined from channel-like noise and charge movements of ion transport. , 1996, Biophysical journal.

[7]  T. Iwamoto,et al.  Phosphorylation-dependent Regulation of Cardiac Na+/Ca2+ Exchanger via Protein Kinase C* , 1996, The Journal of Biological Chemistry.

[8]  D. Bers,et al.  Na‐Ca Exchange and Ca Fluxes during Contraction and Relaxation in Mammalian Ventricular Muscle a , 1996, Annals of the New York Academy of Sciences.

[9]  J. Reeves,et al.  Sodium-Calcium Exchange and Store-dependent Calcium Influx in Transfected Chinese Hamster Ovary Cells Expressing the Bovine Cardiac Sodium-Calcium Exchanger , 1996, The Journal of Biological Chemistry.

[10]  J. Gardner,et al.  ATP-dependent Regulation of Sodium-Calcium Exchange in Chinese Hamster Ovary Cells Transfected with the Bovine Cardiac Sodium-Calcium Exchanger (*) , 1995, The Journal of Biological Chemistry.

[11]  J. Weiss,et al.  Regulation of the cardiac Na(+)-Ca2+ exchanger by Ca2+. Mutational analysis of the Ca(2+)-binding domain , 1995, The Journal of general physiology.

[12]  D. Nicoll,et al.  Identification of the high affinity Ca(2+)-binding domain of the cardiac Na(+)-Ca2+ exchanger. , 1994, The Journal of biological chemistry.

[13]  S. Matsuoka,et al.  Inactivation of outward Na(+)‐Ca2+ exchange current in guinea‐pig ventricular myocytes. , 1994, The Journal of physiology.

[14]  R. Dipolo,et al.  Effects of vanadate on MgATP stimulation of Na-Ca exchange support kinase-phosphatase modulation in squid axons. , 1994, The American journal of physiology.

[15]  S. Matsuoka,et al.  Initial localization of regulatory regions of the cardiac sarcolemmal Na(+)-Ca2+ exchanger. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[16]  J. Reeves,et al.  Stable expression of the cardiac sodium-calcium exchanger in CHO cells. , 1993, The American journal of physiology.

[17]  R. Dipolo,et al.  Effects of some metal‐ATP complexes on Na(+)‐Ca2+ exchange in internally dialysed squid axons. , 1993, The Journal of physiology.

[18]  S. Matsuoka,et al.  Steady-state and dynamic properties of cardiac sodium-calcium exchange. Secondary modulation by cytoplasmic calcium and ATP , 1992, The Journal of general physiology.

[19]  G. Nagel,et al.  Steady-state and dynamic properties of cardiac sodium-calcium exchange. Sodium-dependent inactivation , 1992, The Journal of general physiology.

[20]  D. Hilgemann,et al.  The giant cardiac membrane patch method: stimulation of outward Na(+)‐Ca2+ exchange current by MgATP. , 1992, The Journal of physiology.

[21]  R. Haworth,et al.  Control of the Na-Ca exchanger in isolated heart cells. I. Induction of Na-Na exchange in sodium-loaded cells by intracellular calcium. , 1991, Circulation research.

[22]  D. Hilgemann,et al.  Charge movement during Na+ translocation by native and cloned cardiac Na+/Ca2+ exchanger , 1991, Nature.

[23]  D. Nicoll,et al.  Molecular cloning and functional expression of the cardiac sarcolemmal Na(+)-Ca2+ exchanger , 1990, Science.

[24]  D. Hilgemann.  Regulation and deregulation of cardiac Na+–Ca2+ exchange in giant excised sarcolemmal membrane patches , 1990, Nature.

[25]  J. Kimura,et al.  Sodium-calcium exchange current. Dependence on internal Ca and Na and competitive binding of external Na and Ca , 1989, The Journal of general physiology.

[26]  J. Reeves,et al.  Site density of the sodium-calcium exchange carrier in reconstituted vesicles from bovine cardiac sarcolemma. , 1988, The Journal of biological chemistry.

[27]  R. Dipolo,et al.  Characterization of the reverse Na/Ca exchange in squid axons and its modulation by Cai and ATP. Cai-dependent Nai/Cao and Nai/Nao exchange modes , 1987, The Journal of general physiology.

[28]  R. Tsien,et al.  A new generation of Ca2+ indicators with greatly improved fluorescence properties. , 1985, The Journal of biological chemistry.

[29]  R. Dipolo.  Calcium influx in internally dialyzed squid giant axons , 1979, The Journal of general physiology.

[30]  D M Bers,et al.  A practical guide to the preparation of Ca2+ buffers. , 1994, Methods in cell biology.