Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1992 Mar;448:53–72. doi: 10.1113/jphysiol.1992.sp019029

Background current in sino-atrial node cells of the rabbit heart.

N Hagiwara 1, H Irisawa 1, H Kasanuki 1, S Hosoda 1
PMCID: PMC1176187  PMID: 1317444

Abstract

1. The Ca2+ current, K+ current, hyperpolarization-activated current, Na(+)-K+ pump current and the Na(+)-Ca2+ exchange current were all blocked by appropriate blockers and the remaining time-independent currents were investigated in single pacemaker cells of the rabbit sino-atrial node using the whole-cell patch clamp technique. 2. Exchanging the bathing solution from Tris-hydroxymethyl-aminomethane hydrochloride (Tris) Na+ free to 150 mM-Na+ induced an inward current and the slope conductance of the current-voltage relationship increased from 0.45 +/- 0.18 to 0.87 +/- 0.33 nS (n = 71) at -50 mV. The remaining conductance in Tris Na(+)-free solution was essentially the same when Tris was substituted with tetraethylammonium (TEA) or N-methyl-D-glucamine (NMG). The current density of the Na(+)-dependent inward current obtained by subtracting the current in Tris Na(+)-free from that in 150 mM-Na+ solution was 0.73 +/- 0.21 pA/pF (n = 71) at -50 mV. We called this current the Na(+)-dependent background current. 3. The membrane conductance was reduced by lowering the temperature of the external solution from 36 to 23 degrees C. In Tris Na(+)-free solution, the temperature-sensitive component was outward at all potentials, whereas it showed a reversal potential at around -20 mV in 150 mM-Na+ solution. This reversal potential was interpreted as a sum of the Cs+ efflux and Na+ influx, by comparing the Na(+)-dependent inward currents obtained at 36 degrees C and those at 23 degrees C. 4. Divalent cations (2 mM-Ni2+, 1 mM-Ba2+ or 2 mM-Ca2+) reduced only the outward current in the Tris Na(+)-free solution, while in the 150 mM-Na+ solution, they reduced both the inward and outward components of the current which had a reversal potential of around -10 mV. 5. Amiloride depressed the membrane conductance in 150 mM-Na+, Cs+ or Rb+ external solution, though only at negative membrane potentials, which suggests amiloride has a voltage-dependent effect on the background current. 6. Removal of Cl- from the external solution or the addition of a Cl- channel blocker (4,4'-dinitrostilbene-2,2'-disulphonic acid disodium salt, DNDS) failed to affect the membrane conductance. 7. When the monovalent cation-dependent inward current was measured by subtracting the current in the Tris solution from those recorded in the various monovalent cation solutions, the current amplitude decreased in the order: Rb+ greater than K+ greater than Cs+ greater than Na+ greater than Li+, which suggests a poor cation selectivity of this current system.(ABSTRACT TRUNCATED AT 400 WORDS)

Full text

PDF
54

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Attwell D., Cohen I., Eisner D., Ohba M., Ojeda C. The steady state TTX-sensitive ("window") sodium current in cardiac Purkinje fibres. Pflugers Arch. 1979 Mar 16;379(2):137–142. doi: 10.1007/BF00586939. [DOI] [PubMed] [Google Scholar]
  2. Boyden P. A., Cranefield P. F., Gadsby D. C., Wit A. L. The basis for the membrane potential of quiescent cells of the canine coronary sinus. J Physiol. 1983 Jun;339:161–183. doi: 10.1113/jphysiol.1983.sp014710. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cavalié A., McDonald T. F., Pelzer D., Trautwein W. Temperature-induced transitory and steady-state changes in the calcium current of guinea pig ventricular myocytes. Pflugers Arch. 1985 Oct;405(3):294–296. doi: 10.1007/BF00582574. [DOI] [PubMed] [Google Scholar]
  4. 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]
  5. Cook D. I., Poronnik P., Young J. A. Characterization of a 25-pS nonselective cation channel in a cultured secretory epithelial cell line. J Membr Biol. 1990 Mar;114(1):37–52. doi: 10.1007/BF01869383. [DOI] [PubMed] [Google Scholar]
  6. Denyer J. C., Brown H. F. Pacemaking in rabbit isolated sino-atrial node cells during Cs+ block of the hyperpolarization-activated current if. J Physiol. 1990 Oct;429:401–409. doi: 10.1113/jphysiol.1990.sp018264. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Denyer J. C., Brown H. F. Rabbit sino-atrial node cells: isolation and electrophysiological properties. J Physiol. 1990 Sep;428:405–424. doi: 10.1113/jphysiol.1990.sp018219. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. DiFrancesco D., Noble D. A model of cardiac electrical activity incorporating ionic pumps and concentration changes. Philos Trans R Soc Lond B Biol Sci. 1985 Jan 10;307(1133):353–398. doi: 10.1098/rstb.1985.0001. [DOI] [PubMed] [Google Scholar]
  9. Ehara T., Noma A., Ono K. Calcium-activated non-selective cation channel in ventricular cells isolated from adult guinea-pig hearts. J Physiol. 1988 Sep;403:117–133. doi: 10.1113/jphysiol.1988.sp017242. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Fenwick E. M., Marty A., Neher E. A patch-clamp study of bovine chromaffin cells and of their sensitivity to acetylcholine. J Physiol. 1982 Oct;331:577–597. doi: 10.1113/jphysiol.1982.sp014393. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Fischmeister R., Ayer R. K., Jr, DeHaan R. L. Some limitations of the cell-attached patch clamp technique: a two-electrode analysis. Pflugers Arch. 1986 Jan;406(1):73–82. doi: 10.1007/BF00582957. [DOI] [PubMed] [Google Scholar]
  12. Gadsby D. C., Nakao M. Steady-state current-voltage relationship of the Na/K pump in guinea pig ventricular myocytes. J Gen Physiol. 1989 Sep;94(3):511–537. doi: 10.1085/jgp.94.3.511. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hagiwara N., Irisawa H., Kameyama M. Contribution of two types of calcium currents to the pacemaker potentials of rabbit sino-atrial node cells. J Physiol. 1988 Jan;395:233–253. doi: 10.1113/jphysiol.1988.sp016916. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hagiwara N., Irisawa H. Modulation by intracellular Ca2+ of the hyperpolarization-activated inward current in rabbit single sino-atrial node cells. J Physiol. 1989 Feb;409:121–141. doi: 10.1113/jphysiol.1989.sp017488. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. 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]
  16. Hume J. R., Giles W. Ionic currents in single isolated bullfrog atrial cells. J Gen Physiol. 1983 Feb;81(2):153–194. doi: 10.1085/jgp.81.2.153. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Iijima T., Irisawa H., Kameyama M. Membrane currents and their modification by acetylcholine in isolated single atrial cells of the guinea-pig. J Physiol. 1985 Feb;359:485–501. doi: 10.1113/jphysiol.1985.sp015598. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Irisawa H., Noma A. Pacemaker currents in mammalian nodal cells. J Mol Cell Cardiol. 1984 Sep;16(9):777–781. doi: 10.1016/s0022-2828(84)80001-2. [DOI] [PubMed] [Google Scholar]
  19. 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]
  20. Kinsella J. L., Aronson P. S. Amiloride inhibition of the Na+-H+ exchanger in renal microvillus membrane vesicles. Am J Physiol. 1981 Oct;241(4):F374–F379. doi: 10.1152/ajprenal.1981.241.4.F374. [DOI] [PubMed] [Google Scholar]
  21. Matsuoka S., Ehara T., Noma A. Chloride-sensitive nature of the adrenaline-induced current in guinea-pig cardiac myocytes. J Physiol. 1990 Jun;425:579–598. doi: 10.1113/jphysiol.1990.sp018119. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Mead R. H., Clusin W. T. Origin of the background sodium current and effects of sodium removal in cultured embryonic cardiac cells. Circ Res. 1984 Jul;55(1):67–77. doi: 10.1161/01.res.55.1.67. [DOI] [PubMed] [Google Scholar]
  23. Nakamura S., Hama K., Asai J., Irisawa H. Observations on the fine structure of nodal, Purkinje and working myocardial cells isolated from rabbit hearts. Arch Histol Jpn. 1986 Mar;49(1):105–116. doi: 10.1679/aohc.49.105. [DOI] [PubMed] [Google Scholar]
  24. Noble D., Noble S. J. A model of sino-atrial node electrical activity based on a modification of the DiFrancesco-Noble (1984) equations. Proc R Soc Lond B Biol Sci. 1984 Sep 22;222(1228):295–304. doi: 10.1098/rspb.1984.0065. [DOI] [PubMed] [Google Scholar]
  25. Noble D. The surprising heart: a review of recent progress in cardiac electrophysiology. J Physiol. 1984 Aug;353:1–50. doi: 10.1113/jphysiol.1984.sp015320. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Noma A., Irisawa H. A time- and voltage-dependent potassium current in the rabbit sinoatrial node cell. Pflugers Arch. 1976 Nov 5;366(2-3):251–258. doi: 10.1007/BF00585886. [DOI] [PubMed] [Google Scholar]
  27. Noma A., Irisawa H. Effects of Na+ and K+ on the resting membrane potential of the rabbit sinoatrial node cell. Jpn J Physiol. 1975;25(3):207–302. [PubMed] [Google Scholar]
  28. Noma A., Nakayama T., Kurachi Y., Irisawa H. Resting K conductances in pacemaker and non-pacemaker heart cells of the rabbit. Jpn J Physiol. 1984;34(2):245–254. doi: 10.2170/jjphysiol.34.245. [DOI] [PubMed] [Google Scholar]
  29. Ohara M., Kameyama M., Noma A., Irisawa H. [Giga-seal suction electrode and its application to single cardiac myocytes]. Nihon Seirigaku Zasshi. 1983;45(10):629–639. [PubMed] [Google Scholar]
  30. Seyama I. Characteristics of the anion channel in the sino-atrial node cell of the rabbit. J Physiol. 1979 Sep;294:447–460. doi: 10.1113/jphysiol.1979.sp012940. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Toda N., West T. C. Interactions of K, Na, and vagal stimulation in the S-A node of the rabbit. Am J Physiol. 1967 Feb;212(2):416–423. doi: 10.1152/ajplegacy.1967.212.2.416. [DOI] [PubMed] [Google Scholar]
  32. Yanagihara K., Noma A., Irisawa H. Reconstruction of sino-atrial node pacemaker potential based on the voltage clamp experiments. Jpn J Physiol. 1980;30(6):841–857. doi: 10.2170/jjphysiol.30.841. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES