Abstract
1. In sodium-containing solutions, up to 60% of the slow outward current in Purkinje fibres can be activated by depolarizations which are too small to activate the fast sodium conductance responsible for the depolarization phase of the action potential. This result reinforces the view that the slow outward current results from slow activation of the potassium conductance rather than from slow inactivation of the sodium conductance.
2. These subthreshold changes in membrane conductance are probably responsible for the dependence of the action potential and pace-maker potential durations on small changes in membrane potential in the subthreshold region.
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Selected References
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- 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]
- 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]
- DRAPER M. H., WEIDMANN S. Cardiac resting and action potentials recorded with an intracellular electrode. J Physiol. 1951 Sep;115(1):74–94. doi: 10.1113/jphysiol.1951.sp004653. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 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]
- 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]
- 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]
- 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]
- 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]
- 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]
- WEIDMANN S. Effect of current flow on the membrane potential of cardiac muscle. J Physiol. 1951 Oct 29;115(2):227–236. doi: 10.1113/jphysiol.1951.sp004667. [DOI] [PMC free article] [PubMed] [Google Scholar]