Summary
Guinea pig papillary muscle was exposed to Tyrode solution to which no Ca had been added (Ca-free) and to various concentrations of EDTA in either Tyrode or Ca-free Tyrode. The results were as follows:
-
1.
During 15 to 20 min exposure to Ca-free Tyrode the force of contraction of papillary muscles initially declined rapidly and then at varying rates and to varying degrees. Action potential duration and resting potential were reduced but maximum upstroke velocity (dV/dt max) was increased. The effects were essentially reversed upon Ca replacement.
-
2.
Exposure to 0.8 mM EDTA in Ca-free Tyrode or 2.5 mM EDTA in Tyrode produced similar effects as exposure to Ca-free Tyrode although the rates of change were more rapid and contraction was always abolished.
-
3.
Exposure to 2.5 or 5.0 mM EDTA in Ca-free Tyrode or 5 mM EDTA in Tyrode caused a very rapid loss of measurable contraction, a decrease in resting potential, a marked increase in action potential duration and an increase ind V/dt max. Replacement of Ca caused a beat to beat decrease in action potential duration, an increase in resting potential, a decrease ind V/dt max and often an increase in resting tension. Contraction was initiated within 15 to 20 sec associated with marked after-contractions. As the after-contraction amplitude declined there was a decrease in resting tension. Action potential duration and resting potential recovered during 10 to 15 min after Ca replacement altough plateau duration usually did not return to control value.
The results indicate that the effects of Ca removal on guinea pig ventricular muscle depend on the rate of removal. Transmembrane electrical changes are proposed to be the result of membrane permeability changes resulting in an increase in both general and Na-specific leakage. After-contractions are considered to be the result of intracellular Ca overload due to increased membrane permeability to Ca.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Coraboeuf, E., Vassort, G.: Effects of some inhibitors of ionic permeabilities on ventricular action potential and contraction of rat and guinea pig hearts. Electrocardiology1, 19–30 (1968).
Fleckenstein, A., Tritthart, H., Fleckenstein, B., Herbst, A., Grün, G.: Eine neue Gruppe kompetitiver Ca++-Antagonisten (Iproveratil, D 600, Prenylamin) mit starken Hemmeffekten auf die elektromechanische Koppelung im Warmblütermyokard. Pflügers Arch.307, R25 (1969).
Gabel, L. P., Bihler, I., Dresel, P.: Induction of failure in gas perfused hearts by intermittent administration of Krebs solution. The effect of digitalis glycosides. Circulat. Res.21, 263–269 (1967).
Garnier, D., Rougier, O., Gargouil, Y. M., Coraboeuf, E.: Analyse électrophysiologique du plateau des résponses myocardiques: mise en évidence d'un courant lent en absence d'ions bivalent. Pflügers Arch.313, 321–342 (1969).
Gibbs, C. L., Vaughan, P.: The effect of calcium depletion upon the tension-independent component of cardiac heat production. J. gen. Physiol.52, 532–549 (1968).
Goto, M., Abe, Y.: Effects of EDTA on the membrane potential and tension of ventricular muscle of the rabbit. Jap. J. Physiol.14, 135–146 (1964).
Hoffman, B. F., Suckling, E. E.: Effects of several cations on transmembrane-potentials of cardiac muscle. Amer. J. Physiol.186, 317–324 (1956).
Katzung, B.: Diastolic oscillation on muscle tension and length. J. cell. comp. Physiol.64, 103–115 (1964).
Kaufmann, R., Fleckenstein, A., Antoni, H.: Ursachen und Auslösungsbedingungen von Myokard-Kontraktionen ohne reguläres Aktionspotential. Pflügers Arch. ges. Physiol.278, 435–446 (1963).
Kaufmann, R., Fleckenstein, A.: Ca++-kompetitive elektromechanische Entkoppelung durch Ni++ und Co++ Ionen am Warmblütermyokard. Pflügers Arch. ges. Physiol.282, 290–297 (1965).
Kleinfeld, M., Stein, E., Agullardo, E.: Divalent cations on action potentials of dog heart. Amer. J. Physiol.211, 1438–1442 (1966).
Kleinfeld, M., Stein, E.: Action of divalent cations on membrane potentials and contractility in rat atrium. Amer. J. Physiol.215, 593–599 (1968).
Krause, H., Antoni, H., Fleckenstein, A.: Ein elektronisches Modell für die Bildung lokaler und fortgeleiteter Erregungen an der Myokardfaser auf der Grundlage variabler Strom-Spannungs-Kennlinien für K+ und Na++. Pflügers Arch. ges. Physiol.289, 12–36 (1966).
Langer, G. A.: Calcium exchange in dog ventricular muscle: relation to frequency of contraction and maintenance of contractility. Circulat. Res.17, 78–89 (1965).
Lee, Y. C. P., Ricjman, H. G., Visscher, M. B.: Extracellular calcium ion activity and reversible cardiac arrest. Amer. J. Physiol.210, 493–498 (1966).
Muir, A. R.: The effects of divalent cations on the ultrastructure of the perfused rat heart. J. Anat. (Lond.)101, 239–261 (1967).
Reiter, M.: Die Entstehung von “Nachkontraktionen” im Herzmuskel unter Einwirkung von Calcium und von Digitalisglykosiden in Abhängigkeit von der Reizfrequenz. Naunyn-Schmiedebergs Arch. exp. Path. Pharmak.242, 497 (1962).
Sanborn, W. G., Langer, G. A.: Specific uncoupling of excitation and contraction in mammalian cardiac tissue by lanthanum. J. gen. Physiol.56, 191–217 (1970).
Ware, F.: Effects of calcium deficiency and excess on transmembrane potentials in frog heart. Amer. J. Physiol.186, 1113–1119 (1961).
Winegrad, S.: Studies of cardiac muscle with a high permeability to calcium produced by treatment with EDTA. J. gen. Physiol.58, 71–93 (1971).
Zimmerman, A. N. E., Hülsmann, W. C.: Paradoxical influence of calcium ions on the permeability of cell membranes of the isolated rat heart. Nature (Lond.)211, 646–647 (1966).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tritthart, H., MacLeod, D.P., Stierle, H.E. et al. Effects of Ca-free and EDTA-containing Tyrode solution on transmembrane electrical activity and contraction in guinea pig papillary muscle. Pflugers Arch. 338, 361–376 (1973). https://doi.org/10.1007/BF00586077
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00586077