Abstract
Voltage-gated potassium (Kv) channels exist in the membranes of all living cells. Of the functional classes of Kv channels, the Kv1 channels are the largest and the best studies and are known to play essential roles in excitable cell function, providing an essential counterpoin to the various inward currents that trigger excitability. The serum potassium concentration [K +o ] is tightly regulated in mammals and disturbances can cause significant functional alterations in the electrical behavior of excitable tissues in the nervous system and the heart. At least some of these changes may be mediated by Kv channels that are regulated by changes in the extracellular K+ concentration. As well as changes in serum [K +o ], tissue acification is a frequent pathological condition known to inhibit Shaker and Kv1 voltage-gated potassium channels. In recent studies, it has become recognized that the acidification-induced inhibition of some Kv1 channels is K +o -dependent, and the suggestion has been made that pH and K +o may regulate the channels via a common mechanism. Here we discuss P/C type inactivation as the common pathway by which some Kv channels become unavailable at acid pH and lowered K +o . It is suggested that binding of protons to a regulatory site in the outer pore mouth of some Kv channels favors transitions to the inactivated state, whereas K+ ions exert countereffects. We suggest that modulation of the number of excitable voltage-gated K+ channels in the open vs inactivated states of the channels by physiological H+ and K+ concentrations represents an important pathway to control Kv channel function in health and disease.
Similar content being viewed by others
References
Bennett, P. B. and Begenisich, T. B. (1987) Catecholamines modulate the delayed rectifying potassium current (IK) in guinea pig ventricular myocytes. Pflugers Arch. 410, 217–219.
Apkon, M. and Nerbonne, J. M. (1988) a1-adrenergic agonists selectively suppress voltage-dependent K+ currents in rat ventricular myocytes. Proc. Natl. Acad. Sci. U. S. A. 85, 8756–8760.
Fedida, D., Shimoni, Y., and Giles, W. R. (1990) a-Adrenergic modulation of the transient outward current in rabbit atrial myocytes. J. Physiol. 423, 257–277.
Parker, C. and Fedida, D. (1999) Adrenergic and cholinergic regulation of cardiac K+ channels, in Potassium Channels in Cardiovascular Biology (Archer, S. A. and Rusch, N. J., eds.), Amsterdam: Kluwer.
Zipes, D. P. (1992) Genesis of cardiac arrhythmias: electrophysiological considerations, in Heart Disease, A Textbook of Cardiovascular Medicine (Braunwald, E., ed.), Philadelphia: W. B. Saunders Co.; pp. 588–627.
Doyle, D. A., Cabral, J. M., Pfuetzner, R. A., Kuo, A. L., Gulbis, J. M., Cohen, S. L., et al. (1998) The structure of the potassium channel: molecular basis of K+ conduction and selectivity. Science 280, 69–77.
Zhou, Y. F., Morais-Cabral, J. H., Kaufman, A., and MacKinnon, R. (2001) Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 angstrom resolution. Nature 414, 43–48.
Abraham, M. R., Jahangir, A., Alekseev, A. E., and Terzic, A. (1999) Channelopathies of inwardly rectifying potassium channels. FASEB J. 13, 1901–1910.
Patel, A. J. and Honoré, E. (2001) Properties and modulation of mammalian 2P domain K+ channels. Trends Neurosci. 24, 339–346.
Choe, S. (2002) Potassium channel structures. Nat. Rev. Neurosci. 3, 115–121.
Fedida, D., Wible, B., Wang, Z., Fermini, B., Faust, F., Nattel, S., et al. (1993) Identity of a novel delayed rectifier current from human heart with a cloned K+ channel current. Circ. Res. 73, 210–216.
Feng, J. L., Wible, B., Li G. R., Wang, Z. G., and Nattel, S. (1997) Antisense oligodeoxynucleotides directed against Kv1.5 mRNA specifically inhibit ultrarapid delayed rectifier K+ current in cultured adult human atrial myocytes. Circ. Res. 80, 572–579.
Van Wagoner, D. R. (2000) Pharmacologic relevance of K+ channel remodeling in atrial fibrillation. J. Mol. Cell. Cardiol. 32, 1763–1766.
Fedida, D., Eldstrom, J., Hesketh, J. C., Lamorgese, M., Castel, L., Steele, D. F., et al. (2003) Kv1.5 is an important component of repolarizing K+ current in canine atrial myocytes. Circ. Res. 93, 744–751.
Van Wagoner, D. R., Pond, A. L., McCarthy, P. M., Trimmer, J. S., and Nerbonne, J. M. (1997) Outward K+ current densities and Kv1.5 expression are reduced in chronic human atrial fibrillation. Circ. Res. 80, 772–781.
Van Wagoner, D. R. (2003) Electrophysiological remodeling in human atrial fibrillation. Pacing Clin. Electrophysiol. 26, 1572–1575.
Brundel, B. J., Van Gelder, I. C., Henning, R. H., Tuinenburg, A. E., Wietses, M., Grandjean, J. G., et al. (2001) Alterations in potassium channel gene expression in atria of patients with persistent and paroxysmal atrial fibrillation: differential regulation of protein and mRNA levels for K+ channels. J. Am. Coll. Cardiol. 37, 926–932.
Grammer, J. B., Bosch, R. F., Kuhlkamp, V., and Seipel, L. (2000) Molecular remodeling of Kv4.3 potassium channels in human atrial fibrillation. J. Cardiovasc. Electrophysiol. 11, 626–633.
Kääb, S., Dixon, J., Duc, J., Ashen, D., Näbauer, M., Beuckelmann, D. J., et al. (1998) Molecular basis of transiet outward potassium current downregulation in human heart failure—a decrease in Kv4.3 mRNA correlates with a reduction in current density. Circulation 98, 1383–1393.
Takimoto, K., Li, D. Q., Hershman, K. M., Li, P., Jackson, E. K., and Levitan, E. S. (1997) Decreased expression of Kv4.2 and novel Kv4.3 K+ channel subunit mRNAs in ventricles of renovascular hypertensive rats. Circ. Res. 81, 533–539.
Wakisaka, Y., Niwano, S., Niwano, H., Saito, J., Yoshida, T., Hirasawa, S., et al. (2004) Structural and electrical ventricular remodeling in rat acute myocarditis and subsequent heart failure. Cardiovasc. Res. 63, 689–699.
Gidh-Jain, M., Huang, B., Jain, P., and El-Sherif, N. (1996) Differential expression of voltagegated K+ channel genes in left ventricular remodeled myocardium after experimental myocardial infarction. Circ. Res. 79, 669–675.
Gidh-Jain, M., Huang, B., Jain, P., Gick, G., and El Sherif, N. (1998) Alterations in cardiac gene expression during ventricular remodeling following experimental myocardial infarction. J. Mol. Cell Cardiol. 30, 627–637.
Takimoto, K. and Levitan, E. S. (1994) Glucocorticoid induction of Kv1.5 K+ channel gene expression in ventricle of rat heart. Circ. Res. 75, 1006–1013.
Takimoto, K. and Levitan, E. S. (1996) Altered K+ channel subunit composition following hormone induction of Kv1.5 gene expression. Biochemistry 35, 14149–14156.
Song, M., Helguera, G., Eghbali, M., Zhu, N., Zarei, M. M., Olcese, R., et al. (2001) Remodeling of Kv4.3 potassium channel gene expression under the control of sex hormones. J. Biol. Chem. 276, 31883–31890.
Levitan, E. S., Hershman, K. M., Sherman, T. G., and Takimoto, K. (1996) Dexamethasone and stress upregulate Kv1.5 K+ channel gene expression in rat ventricular myocytes. Neuropharmacology 35, 1001–1006.
Shimoni, Y., Severson, D., and Giles, W. R. (1995) Thyroid status and diabetes modulate regional differences in potassium currents in rat ventricle. J. Physiol. 488, 673–688.
Shimoni, Y., Fiset, C., Clark, R. B., Dixon, J. E., McKinnon, D., Giles, and W. R. (1997) Thyroid hormone regulates postnatal expression of transient K+ channel isoforms in rat ventricle. J. Physiol. 500, 65–73.
Wickenden, A. D., Kaprielian, R., Parker, T. G., Jones, O. T., and Backx, P. H. (1997) Effects of development and thyroid hormone on K+ currents and K+ channel gene expression in rat ventricle. J. Physiol. 504, 271–286.
Wickenden, A. D., Kaprielian, R., You, X. M., and Backx, P. H. (2000) The thyroid hormone analog DITPA restores I(to) in rats after myocardial infarction. Am. J. Physiol. Heart Circ. Physiol. 278, H1105-H1116.
Ojamaa, K., Kenessey, A., Shenoy, R., and Klein, I. (2000) Thyroid hormone metabolism and cardiac gene expression after acute myocardial infarction in the rat. Am. J. Physiol. Endocrinol. Metab. 279, E1319-E1324.
Steidl, J. V. and Yool, A. J. (1999) Differential sensitivity of voltage-gated potassium channels Kv1.5 and Kv1.2 to acidic pH and molecular identification of pH sensor. Mol. Pharmacol. 55, 812–820.
Kehl, S. J., Eduljee, C., Kwan, D. C. H., Zhang, S., and Fedida, D. (2002) Molecular determinants of the inhibition of human Kv1.5 potassium currents by external protons and Zn2+. J. Physiol. 541, 9–24.
Jäger, H. and Grissmer, S. (2001) Regulation of mammalian Shaker-related potassium channel, hKv1.5, by extracellular potassium and pH. FEBS Lett. 488, 45–50.
Perez-Cornejo, P., Stampe, P., and Begenisich, T. (1998) Proton probing of the charybdotoxin binding site of Shaker K+ channels. J. Gen. Physiol. 111, 441–450.
Claydon, T. W., Boyett, M. R., Sivaprasadarao, A., Ishii, K., Owen, J. M., O'Beirne, H. A., et al. (2000) Inhibition of the K+ channel Kv1.4 by acidosis: protonation of an extracellular histidine slows the recovery from N-type inactivation. J. Physiol. 526, 253–264.
Ishii, K., Nunoki, K., Yamagishi, T., Okada, H., and Taira, N. (2001) Differential sensitivity of Kv1.4, Kv1.2, and their tandem channel to acidic pH: Involvement of a histidine residue in high sensitivity to acidic pH. J. Pharmacol. Exp. Ther. 296, 405–411.
Pardo, L. A., Heinemann, S. H., Terlau, H., Ludewig, U., Lorra, C., Pongs, O., et al. (1992) Extracellular K+ specifically modulates a rat brain K+ channel. Proc. Natl. Acad. Sci. U. S. A. 89, 2466–2470.
Casteels, K. and Mathieu, C. (2003) Diabetic ketoacidosis. Rev. Endocr. Metab. Disord. 4, 159–166.
Jäger, H., Rauer, H., Nguyen, A. N., Aiyar, J., Chandy, K. G., and Grissmer, S. (1998) Regulation of mammalian Shaker-related K+ channels: evidence for non-conducting closed and non-conducting inactivated states. J. Physiol. 506, 291–301.
Lopez-Barneo, J., Hoshi, T., Heinemann, S. H., and Aldrich RW (1993) Effects of external cations and mutations in the pore region on C-type inactivation of Shaker potassium channels. Recept. Channels 1, 61–71.
Starkus, J. G., Varga, Z., Schonherr, R., and Heinemann, S. H. (2003) Mechanisms of the inhibition of Shaker potassium channels by protons. Pflugers Arch. 447, 44–54.
Guo, W. N., Li, H. L., Aimond, F., Johns, D. C., Rhodes, K. J., Trimmer, J. S., et al. (2002) Role of heteromultimers in the generation of myocardial transient outward K+ currents. Circ. Res. 90, 586–593.
Eghbali, M., Olcese, R., Zarei, M. M., Toro, L., and Stefani, E. (2002) External pore collapse as an inactivation mechanism for Kv4.3 K+ channels. J. Membrane Biol. 188, 73–86.
Jiang, Y. X., Lee, A., Chen, J. Y., Ruta, V., Cadene, M., Chait, B. T., et al. (2003) X-ray structure of a voltage-dependent K+ channel. Nature 423, 33–41.
Jiang, Y. X., Ruta, V., Chen, J. Y., Lee, A., and MacKinnon, R. (2003) The principle of gating charge movement in a voltage-dependent K+ channel. Nature 423, 42–48.
Gandhi, C. S., Clark, E., Loots, E., Pralle, A., and Isacoff, E. Y. (2003) The orientation and molecular movement of a k(+) channel voltage-sensing domain. Neuron 40, 515–525.
Lee, H. C., Wang, J. M., and Swartz, K. J. (2003) Interaction between extracellular Hanatoxin and the resting conformation of the voltage-sensor paddle in Kv channels. Neuron 40, 527–536.
Ahern, C. A. and Horn, R. (2004) Specificity of charge-carrying residues in the voltage sensor of potassium channels. J. Gen. Physiol. 123, 205–216.
Horn, R. (2004) How S4 segments move charge. Let me count the ways. J. Gen. Physiol. 123, 1–4.
Tempel, B. L., Papazian, D. M., Schwarz, T. L., Jan, Y. N., and Jan, L. Y. (1987) Sequence of a probable potassium channel component encoded at Shaker locus of Drosophila. Science 237, 770–775.
MacKinnon, R., Aldrich, R. W., and Lee, A. W. (1993) Functional stoichiometry of Shaker potassium channel inactivation. Science 262, 757–759.
Antz, C., Bauer, T., Kalbacher, H., Frank, R., Covarrubias, M., Kalbitzer, H. R., et al. (1999) Control of K+ channel gating by protein phosphorylation: structural switches of the inactivation gate. Nat. Struct. Biol. 6, 146–150.
Hoshi, T., Zagotta, W. N., and Aldrich, R. W. (1991) Two types of inactivation in Shaker K+ channels: Effects of alterations in the carboxyterminal region. Neuron 7, 547–556.
Baukrowitz, T. and Yellen, G. (1995) Modulation of K+ current by frequency and external [K+]: A tale of two inactivation mechanisms. Neuron 15, 951–960.
Choi, K. L., Aldrich, R. W., and Yellen, G. (1991) Tetraethylammonium blockade distinguishes two inactivation mechanisms in voltage-activated K+ channels. Proc. Natl. Acad. Sci. U. S. A. 88, 5092–5095.
Ogielska, E. M., Zagotta, W. N., Hoshi, T., Heinemann, S. H., Haab, J., and Aldrich, R. W. (1995) Cooperative subunit interactions in C-type inactivation of K channels. Biophys. J. 69, 2449–2457.
Panyi G., Sheng Z., Tu L., and Deutsch C. (1995) C-type inactivation of a voltage-gated K+ channel occurs by a cooperative mechanism. Biophys. J. 69, 896–903.
Starkus, J. G., Kuschel, L., Rayner, M. D., and Heinemann, S. H. (1997) Ion conduction through C-type inactivated Shaker channels. J. Gen. Physiol. 110, 539–550.
Starkus, J. G., Kuschel, L., Rayner, M. D., and Heinemann, S. H. (1998) Macroscopic Na+ currents in the “nonconducting” Shaker potassium channel mutant W434F. J. Gen. Physiol. 112, 85–93.
DeBiasi, M., Hartmann, H. A., Drewe, J. A., Taglialatela, M., Brown, A. M., and Kirsch, G. E. (1993) Inactivation determined by a single site in K+ pores. Pflugers Arch. 422, 354–363.
Olcese, R., Latorre, R., Toro, L., Bezanilla, F., and Stefani, E. (1997) Correlation between charge movement and ionic current during slow inactivation in Shaker K+ channels. J. Gen. Physiol. 110, 579–589.
Yang, Y. S., Yan, Y. Y., and Sigworth, F. J. (1997) How does the W434F mutation block current in Shaker potassium channels. J. Gen. Physiol. 109, 779–789.
Kiss, L., LoTurco, J., and Korn, S. J. (1999) Contribution of the selectivity filter to inactivation in potassium channels. Biophys. J. 76, 253–263.
Loots, E. and Isacoff, E. Y. (2000) Molecular coupling of S4 to a K+ channel's slow inactivation gate. J. Gen. Physiol. 116, 623–635.
Wang, Z. and Fedida, D. (2001) Gating charge immobilization caused by the transition between inactivated states in the Kv1.5 channel. Biophys. J. 81, 2614–2627.
Klemic, K. G., Shieh, C. C., Kirsch, G. E., and Jones SW (1998) Inactivation of Kv2.1 potassium channels. Biophys. J. 74, 1779–1789.
Klemic, K. G., Kirsch, G. E., and Jones, S. W. (2001) U-type inactivation of Kv3.1 and Shaker potassium channels. Biophys. J. 81, 814–826.
Kurata, H. T., Soon, G. S., and Fedida, D. (2001) Altered state dependence of C-type inactivation in the long and short forms of human Kv1.5. J. Gen. Physiol. 118, 315–332.
Patil, P. G., Brody, D. L., and Yue, D. T. (1998) Preferential closed-state inactivation of neuronal calcium channels. Neuron 20, 1027–1038.
Larsson, H. P. and Elinder, F. (2000) A conserved glutamate is important for slow inactivation in K+ channels. Neuron 27, 573–583.
Ortega-Saenz, P., Pardal, R., Castellano, A., and Lopez-Barneo, J. (2000) Collapse of conductance is prevented by a glutamate residue conserved in voltage-dependent K(+) channels. J. Gen. Physiol. 116, 181–190.
Wang, Z. R., Hesketh, J. C., and Fedida, D. (2000) A high-Na+ conduction state during recovery from inactivation in the K+ channel Kv1.5. Biophys. J. 79, 2416–2433.
Chen, F. S. P., Steele, D., and Fedida, D. (1997) Allosteric effects of permeating cations on gating currents during K+ channel deactivation. J. Gen. Physiol. 110, 87–100.
Loots, E. and Isacoff, E. Y. (1998) Protein rearrangements underlying slow inactivation of the Shaker K+ channel. J. Gen. Physiol. 112, 377–389.
Andalib, P., Consiglio, J. F., Trapani, J. G., and Korn, S. J. (2004) The external TEA binding site and C-type inactivation in voltage-gated potassium channels. Biophys. J. 87, 3148–3161.
Molina, A., Castellano, A. G., and Lopez-Barneo, J. (1997) Pore mutations in Shaker K+ channels distinguish between the sites of tetraethylammonium blockade and C-type inactivation. J. Physiol. 499, 361–367.
Zhang, S., Kurata, H. T., Kehl, S. J., and Fedida, D. (2003) Rapid induction of P/C-type inactivation is the mechanism for acid-induced K+ current inhibition. J. Gen. Physiol. 121, 215–225.
MacKinnon, R. and Yellen, G. (1990) Mutations affecting TEA blockade and ion permeation in voltage- activated K+ channels. Science 250, 276–279.
Heginbotham, L. and MacKinnon, R (1992) The aromatic binding site for tetraethylammonium ion on potassium channels. Neuron 8, 483–491.
Kwan, D. C., Eduljee, C., Lee, L., Zhang, S., Fedida, D., and Kehl, S. J. (2004) The external K+ concentration and mutations in the outer pore mouth affect the inhibition of kv1.5 current by Ni2+. Biophys. J. 86, 2238–2250.
Fedida, D., Maruoka, N. D., and Lin, S. (1999) Modulation of slow inactivation in human cardiac Kv1.5 channels by extra- and intra-cellular permeant cations. J. Physiol. 515, 315–329.
Zhang, S. T., Kwan, D. C. H., Fedida, D., and Kehl, S. J. (2001) External K+ relieves the block but not the gating shift caused by Zn2+ in human Kv1.5 potassium channels. J. Physiol. 532, 349–358.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Fedida, D., Zhang, S., Kwan, D.C.H. et al. Synergistic inhibition of the maximum conductance of Kv1.5 channels by extracellular K+ reduction and acidification. Cell Biochem Biophys 43, 231–242 (2005). https://doi.org/10.1385/CBB:43:2:231
Issue Date:
DOI: https://doi.org/10.1385/CBB:43:2:231