Abstract
Two electroneutral, Na+-driven HCO-3 transporters, the Na+-driven Cl-/HCO-3 exchanger and the electroneutral Na+/ HCO-3 cotransporter, have crucial roles in regulating intracellular pH in a variety of cells, including cardiac myocytes1,2, vascular smooth-muscle3,4, neurons5 and fibroblasts6; however, it is difficult to distinguish their Cl- dependence in mammalian cells. Here we report the cloning of three variants of an electroneutral Na+/HCO-3 cotransporter, NBCn1, from rat smooth muscle. They are 89–92% identical to a human skeletal muscle clone7, 55–57% identical to the electrogenic NBCs and 33–43% identical to the anion exchangers8. When expressed in Xenopus oocytes, NBCn1-B (which encodes 1,218 amino acids) is electroneutral, Na+-dependent and HCO-3-dependent, but not Cl--dependent. Oocytes injected with low levels of NBCn1-B complementary RNA exhibit a Na+ conductance that 4,4-diisothiocyanatostilbene-2,2′-disulphonate stimulates slowly and irreversibly.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Dart, C. & Vaughan-Jones, R. D. Na+-HCO-3 symport in the sheep cardiac Purkinje fibre. J. Physiol. 451, 365–385 (1992).
Lagadic-Gossmann, D., Buckler, K. J. & Vaughan-Jones, R. D. Role of bicarbonate in pH recovery from intracellular acidosis in the guinea-pig ventricular myocyte. J. Physiol. 458, 361–384 (1992).
Aalkjaer, C. & Hughes, A. Chloride and bicarbonate transport in rat resistance arteries. J. Physiol. 436, 57–73 (1991).
Aickin, C. C. Regulation of intracellular pH in the smooth muscle of guinea-pig ureter: Na+ dependence. J. Physiol. 479, 301–316 (1994).
Schwiening, C. J. & Boron, W. F. Regulation of intracellular pH in pyramidal neurons from the rat hippocampus by Na+-dependent Cl--HCO-3 exchange. J. Physiol. 475, 59–67 (1994).
L’Allemain, G., Paris, S. & Pouyssegur, J. Role of a Na+-dependent Cl-/HCO-3 exchange in regulation of intracellular pH in fibroblasts. J. Biol. Chem. 260, 4877–4883 (1985).
Pushkin, A. et al. Cloning, tissue distribution, genomic organization, and functional characterization of NBC3, a new member of the sodium bicarbonate cotransporter family. J. Biol. Chem. 274, 16569–16575 (1999).
Kopito, R. R. & Lodish, H. F. Primary structure and transmembrane orientation of the murine anion exchange protein. Nature 316, 234–238 (1985).
Romero, M. F., Hediger, M. A., Boulpaep, E. L. & Boron, W. F. Expression cloning and characterization of a renal electrogenic Na+/HCO-3 cotransporter. Nature 387, 409–413 (1997).
Romero, M. F., Fong, P., Berger, U. V., Hediger, M. A. & Boron, W. F. Cloning and functional expression of rNBC, an electrogenic Na+-HCO-3 cotransporter from rat kidney. Am. J. Physiol. 274, F425–F432 (1998).
Abuladze, N. et al. Molecular cloning, chromosomal localization, tissue distribution, and functional expression of the human pancreatic sodium bicarbonate cotransporter. J. Biol. Chem. 273, 17689–17695 (1998).
Choi, I., Romero, M. F., Khandoudi, N., Bril, A. & Boron, W. F. Cloning and characterization of a human electrogenic Na+-HCO-3 cotransporter isoform (hhNBC). Am. J. Physiol. 276, C576–C584 (1999).
Kudrycki, K. E., Newman, P. R. & Shull, G. E. cDNA cloning and tissue distribution of mRNAs for two proteins that are related to the Band 3 Cl-HCO3 exchanger. J. Biol. Chem. 265, 462–471 (1990).
Zhao, J., Hogan, E. M., Bevensee, M. O. & Boron, W. F. Out-of-equilibrium CO2/HCO-3 solutions and their use in characterizing a new K/HCO3 cotransporter. Nature 374, 636–639 (1995).
Cabantchik, Z. I., Knauf, P. A. & Rothstein, A. The anion transport system of the red blood cell. The role of membrane protein evaluated by the use of ‘probes’. Biochim. Biophys. Acta 515, 239–302 (1978).
Wadiche, J. I., Amara, S. G. & Kavanaugh, M. P. Ion fluxes associated with excitatory amino acid transport. Neuron 15, 721–728 (1995).
Tzounopoulos, T., Maylie, J. & Adelman, J. P. Induction of endogenous channels by high levels of heterologous membrane proteins in Xenopus oocytes. Biophys. J. 69, 904–908 (1995).
Bielfeld-Ackermann, A., Range, C. & Korbmacher, C. Maitotoxin (MTX) activates a nonselective cation channel in Xenopus laevis oocytes. Pflügers Arch. 436, 329–337 (1998).
Orchard, C. H. & Kentish, J. C. Effects of changes of pH on the contractile function of cardiac muscle. Am. J. Physiol. 258, C967–C981 (1990).
Aalkjaer, C. & Poston, L. Effects of pH on vascular tension: which are the important mechanisms? J. Vasc. Res. 33, 347–359 (1996).
Smith, G. L., Austin, C., Crichton, C. & Wray, S. A review of the actions and control of intracellular pH in vascular smooth muscle. Cardiovasc. Res. 38, 316–331 (1998).
Yu, M., Sandmann, S. & Unger, T. Angiotensin AT2 receptor mediates expression of Na+-HCO-3 symporter in rat myocardium after experimental myocardial infarction. Hypertension 32, 807 (1998).
Sambrook, J., Fritsch, E. F., Maniatis, T. Molecular Cloning: a Laboratory Manual 2nd edn (Cold Spring Harbor Press, Cold Spring Harbor, 1989).
Trudeau, M. C., Warmke, J. W., Ganetzky, B. & Robertson, G. A. HERG, a human inward rectifier on the voltage-gated potassium channel family. Science 269, 92–95 (1995).
Siebens, A. W. & Boron, W. F. Effect of electroneutral luminal and basolateral lactate transport on intracellular pH in salamander proximal tubules. J. Gen. Physiol. 90, 799–831 (1987).
Kopito, R. R. et al. Regulation of intracellular pH by a neuronal homolog of the erythrocyte anion exchanger. Cell 59, 927–937 (1989).
Kim, E., Niethammer, M., Rothschild, A., Jan, Y. N. & Sheng, M. Clustering of Shaker-type K+ channels by interaction with a family of membrane-associated guanylate kinases. Nature 378, 85–88 (1995).
Short, D. B. et al. An apical PDZ protein anchors the cystic fibrosis transmembrane conductance regulator to the cytoskeleton. J. Biol. Chem. 273, 19797–19801 (1998).
Acknowledgements
We thank B. Schmitt, M. Bevensee and M. Romero for valuable discussions. We also thank D. Wong for computer support. This work was supported by NIH grants (W.F.B.) and by the Danish Council (C.A.). I.C. was supported by a postdoctoral fellowship form the American Heart Association.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Choi, I., Aalkjaer, C., Boulpaep, E. et al. An electroneutral sodium/bicarbonate cotransporter NBCn1 and associated sodium channel. Nature 405, 571–575 (2000). https://doi.org/10.1038/35014615
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/35014615
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.