Abstract
Transmembrane potentials were recorded simultaneously from pairs of ventricular fibers in an isolated, regularly beating preparation. A double-barrelled microelectrode was used to record the potentials from, and to polarize, one fiber. A single microelectrode was used to record from a distant fiber. The existence of two systems of fibers, termed P and V, was confirmed. Histological evidence for the existence of two types of fibers is also presented. Electrotonic current spread was observed within both systems, electrotonic interaction between the two systems was rare and always weak. In the case of those pairs of fibers showing electrotonic interaction, the distance for an e-fold decrease in magnitude of the electrotonic potentials was found to be from 300 to 600 µ in P fibers and from 100 to 300 µ in V fibers. However, no electrotonic interaction could be observed in the majority of V fiber pairs. Moreover, the magnitude of the electrotonic potential did not decay monotonically with distance in any one direction. It is concluded that the rabbit ventricle cannot be regarded as a single freely interconnected syncytium.
Full Text
The Full Text of this article is available as a PDF (814.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- ALANIS J., BENITEZ D., PILAR G. A functional discontinuity between the Purkinje and ventricular muscle cells. Acta Physiol Lat Am. 1961;11:171–183. [PubMed] [Google Scholar]
- CRANEFIELD P. F., HOFFMAN B. F. Propagated repolarization in heart muscle. J Gen Physiol. 1958 Mar 20;41(4):633–649. doi: 10.1085/jgp.41.4.633. [DOI] [PMC free article] [PubMed] [Google Scholar]
- GEORGE E. P. Resistance values in a syncytium. Aust J Exp Biol Med Sci. 1961 Jun;39:267–274. doi: 10.1038/icb.1961.27. [DOI] [PubMed] [Google Scholar]
- JOHNSON E. A., TILLE J. Changes in polarisation resistance during the repolarisation phase of the rabbit ventricular action potential. Aust J Exp Biol Med Sci. 1960 Dec;38:509–513. doi: 10.1038/icb.1960.56. [DOI] [PubMed] [Google Scholar]
- JOHNSON E. A., TILLE J. Evidence for independence of voltage of the membrane conductance of rabbit ventricular fibres. Nature. 1961 Nov 18;192:663–664. doi: 10.1038/192663a0. [DOI] [PubMed] [Google Scholar]
- JOHNSON E. A., TILLE J. Investigations of the electrical properties of cardiac muscle fibres with the aid of intracellular double-barrelled electrodes. J Gen Physiol. 1961 Jan;44:443–467. doi: 10.1085/jgp.44.3.443. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 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]
- SPERELAKIS N., LEHMKUHL D. EFFECT OF CURRENT ON TRANSMEMBRANE POTENTIALS IN CULTURED CHICK HEART CELLS. J Gen Physiol. 1964 May;47:895–927. doi: 10.1085/jgp.47.5.895. [DOI] [PMC free article] [PubMed] [Google Scholar]
- TARR M., SPERELAKIS N. WEAK ELECTROTONIC INTERACTION BETWEEN CONTIGUOUS CARDIAC CELLS. Am J Physiol. 1964 Sep;207:691–700. doi: 10.1152/ajplegacy.1964.207.3.691. [DOI] [PubMed] [Google Scholar]
- WEIDMANN S. The electrical constants of Purkinje fibres. J Physiol. 1952 Nov;118(3):348–360. doi: 10.1113/jphysiol.1952.sp004799. [DOI] [PMC free article] [PubMed] [Google Scholar]