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. 1969 Jan;200(1):205–231. doi: 10.1113/jphysiol.1969.sp008689

Outward membrane currents activated in the plateau range of potentials in cardiac Purkinje fibres

D Noble, R W Tsien
PMCID: PMC1350425  PMID: 5761944

Abstract

1. The membrane currents in Purkinje fibres under voltage clamp conditions have been investigated in the range of potentials at which the action potential plateau occurs. The results show that in this range slow outward current changes occur which are quite distinct from the potassium current activated in the pace-maker range of potentials.

2. The time course of current change in response to step voltage changes is non-exponential. At each potential the current changes may be analysed in terms of the sum of two exponential changes and this property has been used to dissect the currents into two components, ix1 and ix2, both of which have been found to obey kinetics of the Hodgkin—Huxley type.

3. The first component, ix1, is activated with a time constant of about 0·5 sec at the plateau. At more positive and more negative potentials the time constants are shorter. The steady-state degree of activation varies from 0 at about -50 mV to about 1 at +20 mV. The instantaneous current—voltage relation is an inward-going rectifier but shows no detectable negative slope. In normal Tyrode solution ([K]0 = 4 mM) the reversal potential is about -85 mV.

4. The second component, ix2, is activated extremely slowly and the time constant at the plateau is about 4 sec. The steady-state activation curve varies from 0 at about -40 mV to 1 at about +20 mV. The instantaneous current—voltage relation is nearly linear. The reversal potential occurs between -50 and -20 mV in different preparations.

5. It is suggested that these currents are carried largely by K ions, but that some other ions (e.g. Na) also contribute so that the reversal potentials are positive to EK.

6. The relation of these results to previous work on delayed rectification in cardiac muscle is discussed.

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Selected References

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

  1. ARMSTRONG C. M., BINSTOCK L. ANOMALOUS RECTIFICATION IN THE SQUID GIANT AXON INJECTED WITH TETRAETHYLAMMONIUM CHLORIDE. J Gen Physiol. 1965 May;48:859–872. doi: 10.1085/jgp.48.5.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Adrian R. H., Freygang W. H. The potassium and chloride conductance of frog muscle membrane. J Physiol. 1962 Aug;163(1):61–103. doi: 10.1113/jphysiol.1962.sp006959. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Armstrong C. M. Time course of TEA(+)-induced anomalous rectification in squid giant axons. J Gen Physiol. 1966 Nov;50(2):491–503. doi: 10.1085/jgp.50.2.491. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Brady A. J., Woodbury J. W. The sodium-potassium hypothesis as the basis of electrical activity in frog ventricle. J Physiol. 1960 Dec;154(2):385–407. doi: 10.1113/jphysiol.1960.sp006586. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. CARMELIET E. E. Chloride ions and the membrane potential of Purkinje fibres. J Physiol. 1961 Apr;156:375–388. doi: 10.1113/jphysiol.1961.sp006682. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. DECK K. A., KERN R., TRAUTWEIN W. VOLTAGE CLAMP TECHNIQUE IN MAMMALIAN CARDIAC FIBRES. Pflugers Arch Gesamte Physiol Menschen Tiere. 1964 Jun 9;280:50–62. doi: 10.1007/BF00412615. [DOI] [PubMed] [Google Scholar]
  7. DECK K. A., TRAUTWEIN W. IONIC CURRENTS IN CARDIAC EXCITATION. Pflugers Arch Gesamte Physiol Menschen Tiere. 1964 Jun 9;280:63–80. doi: 10.1007/BF00412616. [DOI] [PubMed] [Google Scholar]
  8. Dudel J., Peper K., Rüdel R., Trautwein W. The dynamic chloride component of membrane current in Purkinje fibers. Pflugers Arch Gesamte Physiol Menschen Tiere. 1967;295(3):197–212. doi: 10.1007/BF01844100. [DOI] [PubMed] [Google Scholar]
  9. Dudel J., Peper K., Rüdel R., Trautwein W. The effect of tetrodotoxin on the membrane current in cardiac muscle (Purkinje fibers). Pflugers Arch Gesamte Physiol Menschen Tiere. 1967;295(3):213–226. doi: 10.1007/BF01844101. [DOI] [PubMed] [Google Scholar]
  10. Dudel J., Peper K., Rüdel R., Trautwein W. The potassium component of membrane current in Purkinje fibers. Pflugers Arch Gesamte Physiol Menschen Tiere. 1967;296(4):308–327. doi: 10.1007/BF00362531. [DOI] [PubMed] [Google Scholar]
  11. FRANKENHAEUSER B. A QUANTITATIVE DESCRIPTION OF POTASSIUM CURRENTS IN MYELINATED NERVE FIBRES OF XENOPUS LAEVIS. J Physiol. 1963 Nov;169:424–430. doi: 10.1113/jphysiol.1963.sp007268. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. HALL A. E., HUTTER O. F., NOBLE D. Current-voltage relations of Purkinje fibres in sodium-deficient solutions. J Physiol. 1963 Apr;166:225–240. doi: 10.1113/jphysiol.1963.sp007102. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. HODGKIN A. L., HOROWICZ P. The influence of potassium and chloride ions on the membrane potential of single muscle fibres. J Physiol. 1959 Oct;148:127–160. doi: 10.1113/jphysiol.1959.sp006278. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. HODGKIN A. L., HUXLEY A. F. A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol. 1952 Aug;117(4):500–544. doi: 10.1113/jphysiol.1952.sp004764. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. HODGKIN A. L., HUXLEY A. F. The components of membrane conductance in the giant axon of Loligo. J Physiol. 1952 Apr;116(4):473–496. doi: 10.1113/jphysiol.1952.sp004718. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. HUTTER O. F., NOBLE D. Anion conductance of cardiac muscle. J Physiol. 1961 Jul;157:335–350. doi: 10.1113/jphysiol.1961.sp006726. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. HUTTER O. F., NOBLE D. Rectifying properties of heart muscle. Nature. 1960 Nov 5;188:495–495. doi: 10.1038/188495a0. [DOI] [PubMed] [Google Scholar]
  18. Hauswirth O., Noble D., Tsien R. W. The mechanism of oscillatory activity at low membrane potentials in cardiac Purkinje fibres. J Physiol. 1969 Jan;200(1):255–265. doi: 10.1113/jphysiol.1969.sp008691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. McAllister R. E., Noble D. The effect of subthreshold potentials on the membrane current in cardiac Purkinje fibres. J Physiol. 1967 May;190(2):381–387. doi: 10.1113/jphysiol.1967.sp008216. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. McAllister R. E., Noble D. The time and voltage dependence of the slow outward current in cardiac Purkinje fibres. J Physiol. 1966 Oct;186(3):632–662. doi: 10.1113/jphysiol.1966.sp008060. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. NOBLE D. A modification of the Hodgkin--Huxley equations applicable to Purkinje fibre action and pace-maker potentials. J Physiol. 1962 Feb;160:317–352. doi: 10.1113/jphysiol.1962.sp006849. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. NOBLE D. The voltage dependence of the cardiac membrane conductance. Biophys J. 1962 Sep;2:381–393. doi: 10.1016/s0006-3495(62)86862-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Noble D. Applications of Hodgkin-Huxley equations to excitable tissues. Physiol Rev. 1966 Jan;46(1):1–50. doi: 10.1152/physrev.1966.46.1.1. [DOI] [PubMed] [Google Scholar]
  24. Noble D., Tsien R. W. Reconstruction of the repolarization process in cardiac Purkinje fibres based on voltage clamp measurements of membrane current. J Physiol. 1969 Jan;200(1):233–254. doi: 10.1113/jphysiol.1969.sp008690. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Noble D., Tsien R. W. The kinetics and rectifier properties of the slow potassium current in cardiac Purkinje fibres. J Physiol. 1968 Mar;195(1):185–214. doi: 10.1113/jphysiol.1968.sp008454. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Reuter H. Slow inactivation of currents in cardiac Purkinje fibres. J Physiol. 1968 Jul;197(1):233–253. doi: 10.1113/jphysiol.1968.sp008557. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Reuter H. The dependence of slow inward current in Purkinje fibres on the extracellular calcium-concentration. J Physiol. 1967 Sep;192(2):479–492. doi: 10.1113/jphysiol.1967.sp008310. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Rougier O., Vassort G., Stämpfli R. Voltage clamp experiments on frog atrial heart muscle fibres with the sucrose gap technique. Pflugers Arch Gesamte Physiol Menschen Tiere. 1968;301(2):91–108. doi: 10.1007/BF00362729. [DOI] [PubMed] [Google Scholar]
  29. Vassalle M. Analysis of cardiac pacemaker potential using a "voltage clamp" technique. Am J Physiol. 1966 Jun;210(6):1335–1341. doi: 10.1152/ajplegacy.1966.210.6.1335. [DOI] [PubMed] [Google Scholar]
  30. WEIDMANN S. The effect of the cardiac membrane potential on the rapid availability of the sodium-carrying system. J Physiol. 1955 Jan 28;127(1):213–224. doi: 10.1113/jphysiol.1955.sp005250. [DOI] [PMC free article] [PubMed] [Google Scholar]

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