Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1971 Dec;219(1):167–189. doi: 10.1113/jphysiol.1971.sp009656

Excitation—contraction coupling in frog ventricle: evidence from voltage clamp studies

M Morad, R K Orkand
PMCID: PMC1331624  PMID: 5316660

Abstract

1. Membrane potential, tension and membrane current were simultaneously recorded from frog ventricular strips in a modified sucrose-gap which enabled control of membrane potential by voltage clamp.

2. Shortening the frog ventricular action potential by repolarizing the membrane to the resting potential terminates contraction.

3. Depolarization to the level of the normal action potential plateau for longer than about 80-100 msec (up to 30 sec) produces and maintains tension for the duration of the depolarization.

4. Depolarizations less than about 80 msec in duration generate no tension but can facilitate the tension response to subsequent depolarizations. The facilitating effect of a short depolarizing pulse persists for no longer than 0·5 sec.

5. The mechanical threshold is about -50 mV; the relation between membrane potential and tension is fairly linear from about +5 to +80 mV.

6. Variation of holding potential, below the mechanical threshold, has no effect on the tension—voltage relation. The absolute membrane potential rather than pulse amplitude determines the developed tension.

7. Increasing external calcium increases the slope of the voltage—tension relation.

8. Contraction of the frog ventricle is directly controlled by the electrical activity of the surface membrane.

Full text

PDF
167

Selected References

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

  1. Antoni H., Rotmann M. Zum Mechanismus der negative inotropen Acetylcholin-Wirkung auf das isolierte Froschmyokard. Pflugers Arch Gesamte Physiol Menschen Tiere. 1968;300(2):67–86. [PubMed] [Google Scholar]
  2. Beeler G. W., Jr, Reuter H. The relation between membrane potential, membrane currents and activation of contraction in ventricular myocardial fibres. J Physiol. 1970 Mar;207(1):211–229. doi: 10.1113/jphysiol.1970.sp009057. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Chapman R. A., Niedergerke R. Interaction between heart rate and calcium concentration in the control of contractile strength of the frog heart. J Physiol. 1970 Dec;211(2):423–443. doi: 10.1113/jphysiol.1970.sp009285. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Fozzard H. A., Sleator W. Membrane ionic conductances during rest and activity in guinea pig atrial muscle. Am J Physiol. 1967 Apr;212(4):945–952. doi: 10.1152/ajplegacy.1967.212.4.945. [DOI] [PubMed] [Google Scholar]
  5. Hagiwara S., Nakajima S. Differences in Na and Ca spikes as examined by application of tetrodotoxin, procaine, and manganese ions. J Gen Physiol. 1966 Mar;49(4):793–806. doi: 10.1085/jgp.49.4.793. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Hellam D. C., Podolsky R. J. Force measurements in skinned muscle fibres. J Physiol. 1969 Feb;200(3):807–819. doi: 10.1113/jphysiol.1969.sp008723. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. KRAFT H. G., WIEGMANN O. Uber die Abhängigkeit der elektrischen umd mechanischen Tätigkeit der Herzstreifenpräparates des Frosches von der Schlagfrequenz. Z Biol. 1957;109(3):210–222. [PubMed] [Google Scholar]
  8. Katz A. M. Contractile proteins of the heart. Physiol Rev. 1970 Jan;50(1):63–158. doi: 10.1152/physrev.1970.50.1.63. [DOI] [PubMed] [Google Scholar]
  9. LUTTGAU H. C., NIEDERGERKE R. The antagonism between Ca and Na ions on the frog's heart. J Physiol. 1958 Oct 31;143(3):486–505. doi: 10.1113/jphysiol.1958.sp006073. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Lamb J. F., McGuigan J. A. Contractures in a superfused frog's ventricle. J Physiol. 1966 Oct;186(2):261–283. doi: 10.1113/jphysiol.1966.sp008033. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Mascher D., Peper K. Two components of inward current in myocardial muscle fibers. Pflugers Arch. 1969;307(3):190–203. doi: 10.1007/BF00592084. [DOI] [PubMed] [Google Scholar]
  12. Morad M., Trautwein W. The effect of the duration of the action potential on contraction in the mammalian heart muscle. Pflugers Arch Gesamte Physiol Menschen Tiere. 1968;299(1):66–82. doi: 10.1007/BF00362542. [DOI] [PubMed] [Google Scholar]
  13. NIEDERGERKE R. MOVEMENTS OF CA IN FROG HEART VENTRICLES AT REST AND DURING CONTRACTURES. J Physiol. 1963 Jul;167:515–550. doi: 10.1113/jphysiol.1963.sp007166. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. NIEDERGERKE R. Movements of Ca in beating ventricles of the frog heart. J Physiol. 1963 Jul;167:551–580. doi: 10.1113/jphysiol.1963.sp007167. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. NIEDERGERKE R. The potassium chloride contracture of the heart and its modification by calcium. J Physiol. 1956 Dec 28;134(3):584–599. doi: 10.1113/jphysiol.1956.sp005667. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Niedergerke R., Page S., Talbot M. S. Calcium fluxes in frog heart ventricles. Pflugers Arch. 1969;306(4):357–360. doi: 10.1007/BF00589161. [DOI] [PubMed] [Google Scholar]
  17. 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]
  18. Rougier O., Vassort G., Garnier D., Gargouil Y. M., Coraboeuf E. Existence and role of a slow inward current during the frog atrial action potential. Pflugers Arch. 1969;308(2):91–110. doi: 10.1007/BF00587018. [DOI] [PubMed] [Google Scholar]
  19. Sommer J. R., Johnson E. A. Cardiac muscle. A comparative ultrastructural study with special reference to frog and chicken hearts. Z Zellforsch Mikrosk Anat. 1969;98(3):437–468. [PubMed] [Google Scholar]
  20. Staley N. A., Benson E. S. The ultrastructure of frog ventricular cardiac muscle and its relationship to mechanism of excitation-contraction coupling. J Cell Biol. 1968 Jul;38(1):99–114. doi: 10.1083/jcb.38.1.99. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. WEIDMANN S. Effect of increasing the calcium concentration during a single heart-beat. Experientia. 1959 Apr 15;15(4):128–128. doi: 10.1007/BF02165518. [DOI] [PubMed] [Google Scholar]
  22. Wood E. H., Heppner R. L., Weidmann S. Inotropic effects of electric currents. I. Positive and negative effects of constant electric currents or current pulses applied during cardiac action potentials. II. Hypotheses: calcium movements, excitation-contraction coupling and inotropic effects. Circ Res. 1969 Mar;24(3):409–445. doi: 10.1161/01.res.24.3.409. [DOI] [PubMed] [Google Scholar]

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

RESOURCES