Summary
The characteristics of the regenerative increase in conductance for Sr ions in cardiac Purkyně fibres was examined as a function of (Sr) e , in the presence and absence of Ca ions. The maximum rate of depolarization during the upstroke of the action potential was not linearly related to log (Sr) e but tended to become constant at high external Sr concentrations, and was also inhibited by increasing Ca concentrations. The conductance for Sr ions as a function of (Sr) e follows Michaëlis-Menten characteristics, suggesting that the Sr conductance is determined by a first order reaction between Sr and a site on the cell membrane. The behaviour in the presence of Ca can be explained by Ca acting as a competitive inhibitor.
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Vereecke, J., Carmeliet, E. Sr action potentials in cardiac Purkyně fibres. Pflugers Arch. 322, 73–82 (1971). https://doi.org/10.1007/BF00586666
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DOI: https://doi.org/10.1007/BF00586666