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. 1988 Sep;403:117–133. doi: 10.1113/jphysiol.1988.sp017242

Calcium-activated non-selective cation channel in ventricular cells isolated from adult guinea-pig hearts.

T Ehara 1, A Noma 1, K Ono 1
PMCID: PMC1190706  PMID: 2473193

Abstract

1. A class of Ca2+-activated non-selective cation channel was identified in ventricular cells, which were dissociated from adult guinea-pig hearts using collagenase. 2. Under cell-attached conditions the patch electrode filled with a Na+-rich solution recorded no obvious single-channel current at the resting membrane potential. Subsequent superfusion of the ventricular cell with a Na+-free Tyrode solution induced an inward-going single-channel current as well as contracture of the cell. Kinetics of this channel were not affected by varying the membrane potential. 3. Single-channel currents showing a conductance similar to those observed in the cell-attached patches were recorded in isolated inside-out membrane patches when the inner side of the membrane was exposed to a free Ca2+ concentration ([Ca2+]i) higher than 0.3 microM. The slope conductance of the channel was 14.8 +/- 2.9 pS (mean +/- S.D., n = 17) at 20-25 degrees C. 4. The reversal potential examined in the inside-out patch was about 0 mV irrespective of the Na+-rich, K+-rich, Li+-rich or Cs+-rich solutions on either side of the membrane, thereby indicating that the channel was almost equally permeable to these cations. 5. The open probability of the channel was increased by raising [Ca2+]i with the maximum value of 0.93 +/- 0.17 (n = 4) at about 10 microM [Ca2+]i. The dose-response relation was fitted to the saturation kinetics with a Hill coefficient of 3.0 and a half-maximum concentration of 1.2 microM [Ca2+]i. 6. The gating kinetics were complex; both the open and closed time histograms showed at least two exponential components with time constants of 3.8 +/- 1.3 ms and 140 +/- 110 ms for open time and 1.8 +/- 1.1 ms and 14.9 +/- 5.3 ms for closed time (n = 4) at 10 microM [Ca2+]i. Reduction of [Ca2+]i resulted in both a decrease of the time constant of the slow component in the open time histogram and an increase of the two time constants of the closed time histogram. 7. Contribution of the channel to the whole-cell current was discussed based on an estimation of the channel density, presumably about 0.04 approximately 0.4/microns 2. Maximum activation of the channel would produce 7.2 approximately 72 nS of membrane conductance, which would explain the reported magnitude of the Ca2+-mediated background conductance of the single myocyte. The channel may also contribute, at least in part, to the transient inward current which develops in Ca2+-overloaded cardiac cells.

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Selected References

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  1. Allen D. G., Eisner D. A., Orchard C. H. Characterization of oscillations of intracellular calcium concentration in ferret ventricular muscle. J Physiol. 1984 Jul;352:113–128. doi: 10.1113/jphysiol.1984.sp015281. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Allen D. G., Kurihara S. Calcium transients in mammalian ventricular muscle. Eur Heart J. 1980;Suppl A:5–15. doi: 10.1093/eurheartj/1.suppl_1.5. [DOI] [PubMed] [Google Scholar]
  3. Arlock P., Katzung B. G. Effects of sodium substitutes on transient inward current and tension in guinea-pig and ferret papillary muscle. J Physiol. 1985 Mar;360:105–120. doi: 10.1113/jphysiol.1985.sp015606. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Barrett J. N., Magleby K. L., Pallotta B. S. Properties of single calcium-activated potassium channels in cultured rat muscle. J Physiol. 1982 Oct;331:211–230. doi: 10.1113/jphysiol.1982.sp014370. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Brown H. F., Noble D., Noble S. J., Taupignon A. I. Relationship between the transient inward current and slow inward currents in the sino-atrial node of the rabbit. J Physiol. 1986 Jan;370:299–315. doi: 10.1113/jphysiol.1986.sp015936. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Callewaert G., Vereecke J., Carmeliet E. Existence of a calcium-dependent potassium channel in the membrane of cow cardiac Purkinje cells. Pflugers Arch. 1986 Apr;406(4):424–426. doi: 10.1007/BF00590947. [DOI] [PubMed] [Google Scholar]
  7. Cannell M. B., Lederer W. J. The arrhythmogenic current ITI in the absence of electrogenic sodium-calcium exchange in sheep cardiac Purkinje fibres. J Physiol. 1986 May;374:201–219. doi: 10.1113/jphysiol.1986.sp016075. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Colquhoun D., Neher E., Reuter H., Stevens C. F. Inward current channels activated by intracellular Ca in cultured cardiac cells. Nature. 1981 Dec 24;294(5843):752–754. doi: 10.1038/294752a0. [DOI] [PubMed] [Google Scholar]
  9. Eisner D. A., Lederer W. J. Na-Ca exchange: stoichiometry and electrogenicity. Am J Physiol. 1985 Mar;248(3 Pt 1):C189–C202. doi: 10.1152/ajpcell.1985.248.3.C189. [DOI] [PubMed] [Google Scholar]
  10. Eisner D. A., Valdeolmillos M. Measurement of intracellular calcium during the development and relaxation of tonic tension in sheep Purkinje fibres. J Physiol. 1986 Jun;375:269–281. doi: 10.1113/jphysiol.1986.sp016116. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Fabiato A., Fabiato F. Calculator programs for computing the composition of the solutions containing multiple metals and ligands used for experiments in skinned muscle cells. J Physiol (Paris) 1979;75(5):463–505. [PubMed] [Google Scholar]
  12. Ferrier G. R., Moe G. K. Effect of calcium on acetylstrophanthidin-induced transient depolarizations in canine Purkinje tissue. Circ Res. 1973 Nov;33(5):508–515. doi: 10.1161/01.res.33.5.508. [DOI] [PubMed] [Google Scholar]
  13. Greene R. W., Haas H. L. Adenosine actions on CA1 pyramidal neurones in rat hippocampal slices. J Physiol. 1985 Sep;366:119–127. doi: 10.1113/jphysiol.1985.sp015788. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  15. Imoto Y., Ehara T., Matsuura H. Voltage- and time-dependent block of iK1 underlying Ba2+-induced ventricular automaticity. Am J Physiol. 1987 Feb;252(2 Pt 2):H325–H333. doi: 10.1152/ajpheart.1987.252.2.H325. [DOI] [PubMed] [Google Scholar]
  16. Isenberg G., Klockner U. Calcium tolerant ventricular myocytes prepared by preincubation in a "KB medium". Pflugers Arch. 1982 Oct;395(1):6–18. doi: 10.1007/BF00584963. [DOI] [PubMed] [Google Scholar]
  17. Kameyama M., Kakei M., Sato R., Shibasaki T., Matsuda H., Irisawa H. Intracellular Na+ activates a K+ channel in mammalian cardiac cells. Nature. 1984 May 24;309(5966):354–356. doi: 10.1038/309354a0. [DOI] [PubMed] [Google Scholar]
  18. Karagueuzian H. S., Katzung B. G. Voltage-clamp studies of transient inward current and mechanical oscillations induced by ouabain in ferret papillary muscle. J Physiol. 1982 Jun;327:255–271. doi: 10.1113/jphysiol.1982.sp014230. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Kass R. S., Lederer W. J., Tsien R. W., Weingart R. Role of calcium ions in transient inward currents and aftercontractions induced by strophanthidin in cardiac Purkinje fibres. J Physiol. 1978 Aug;281:187–208. doi: 10.1113/jphysiol.1978.sp012416. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Kimura J., Miyamae S., Noma A. Identification of sodium-calcium exchange current in single ventricular cells of guinea-pig. J Physiol. 1987 Mar;384:199–222. doi: 10.1113/jphysiol.1987.sp016450. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Latorre R., Miller C. Conduction and selectivity in potassium channels. J Membr Biol. 1983;71(1-2):11–30. doi: 10.1007/BF01870671. [DOI] [PubMed] [Google Scholar]
  22. Lederer W. J., Tsien R. W. Transient inward current underlying arrhythmogenic effects of cardiotonic steroids in Purkinje fibres. J Physiol. 1976 Dec;263(2):73–100. doi: 10.1113/jphysiol.1976.sp011622. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Marty A. Blocking of large unitary calcium-dependent potassium currents by internal sodium ions. Pflugers Arch. 1983 Feb;396(2):179–181. doi: 10.1007/BF00615524. [DOI] [PubMed] [Google Scholar]
  24. Marty A. Ca-dependent K channels with large unitary conductance in chromaffin cell membranes. Nature. 1981 Jun 11;291(5815):497–500. doi: 10.1038/291497a0. [DOI] [PubMed] [Google Scholar]
  25. Maruyama Y., Moore D., Petersen O. H. Calcium-activated cation channel in rat thyroid follicular cells. Biochim Biophys Acta. 1985 Dec 5;821(2):229–232. doi: 10.1016/0005-2736(85)90091-4. [DOI] [PubMed] [Google Scholar]
  26. Maruyama Y., Peterson O. H. Single-channel currents in isolated patches of plasma membrane from basal surface of pancreatic acini. Nature. 1982 Sep 9;299(5879):159–161. doi: 10.1038/299159a0. [DOI] [PubMed] [Google Scholar]
  27. Matsuda H. Effects of intracellular calcium injection on steady state membrane currents in isolated single ventricular cells. Pflugers Arch. 1983 Apr;397(1):81–83. doi: 10.1007/BF00585176. [DOI] [PubMed] [Google Scholar]
  28. Matsuda H., Noma A., Kurachi Y., Irisawa H. Transient depolarization and spontaneous voltage fluctuations in isolated single cells from guinea pig ventricles. Calcium-mediated membrane potential fluctuations. Circ Res. 1982 Aug;51(2):142–151. doi: 10.1161/01.res.51.2.142. [DOI] [PubMed] [Google Scholar]
  29. Noma A. ATP-regulated K+ channels in cardiac muscle. Nature. 1983 Sep 8;305(5930):147–148. doi: 10.1038/305147a0. [DOI] [PubMed] [Google Scholar]
  30. Noma A., Tsuboi N. Dependence of junctional conductance on proton, calcium and magnesium ions in cardiac paired cells of guinea-pig. J Physiol. 1987 Jan;382:193–211. doi: 10.1113/jphysiol.1987.sp016363. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Pallotta B. S. Calcium-activated potassium channels in rat muscle inactivate from a short-duration open state. J Physiol. 1985 Jun;363:501–516. doi: 10.1113/jphysiol.1985.sp015724. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Powell T., Terrar D. A., Twist V. W. Electrical properties of individual cells isolated from adult rat ventricular myocardium. J Physiol. 1980 May;302:131–153. doi: 10.1113/jphysiol.1980.sp013234. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Reuter H., Seitz N. The dependence of calcium efflux from cardiac muscle on temperature and external ion composition. J Physiol. 1968 Mar;195(2):451–470. doi: 10.1113/jphysiol.1968.sp008467. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Sato R., Noma A., Kurachi Y., Irisawa H. Effects of intracellular acidification on membrane currents in ventricular cells of the guinea pig. Circ Res. 1985 Oct;57(4):553–561. doi: 10.1161/01.res.57.4.553. [DOI] [PubMed] [Google Scholar]
  35. Tsien R. Y., Rink T. J. Neutral carrier ion-selective microelectrodes for measurement of intracellular free calcium. Biochim Biophys Acta. 1980 Jul;599(2):623–638. doi: 10.1016/0005-2736(80)90205-9. [DOI] [PubMed] [Google Scholar]
  36. Yellen G. Single Ca2+-activated nonselective cation channels in neuroblastoma. Nature. 1982 Mar 25;296(5855):357–359. doi: 10.1038/296357a0. [DOI] [PubMed] [Google Scholar]
  37. von Tscharner V., Prod'hom B., Baggiolini M., Reuter H. Ion channels in human neutrophils activated by a rise in free cytosolic calcium concentration. 1986 Nov 27-Dec 3Nature. 324(6095):369–372. doi: 10.1038/324369a0. [DOI] [PubMed] [Google Scholar]

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