Correlation of contractile force with a calcium pool in the isolated cat heart.
The relationship between cellular calcium (Ca) stores and isometric contractile force was investigated in isolated, gas-perfused cat hearts. The hearts were preperfused for approximately 5 min with substrate-free Krebs solution modified to contain 0, 1.25, 2.5, 5.0 or 10.0 mEq/liter Ca, gas-perfused for up to 120 min, and then perfused with zero-Ca Krebs solution. Contractile force and [Ca] in the effluent fluid were measured. Our results indicate that: (a) The washout of Ca was characteristic of a three compartment system, (b) A Ca compartment directly associated with muscle contraction was identified by correlation of the rate of Ca washout with the rate of decay of contractility (r = 0.79). (c) Ca content in the compartment was correlated with contractile force (r = 0.77). (d) Contractile force and the Ca content of the compartment which was correlated with contractility approached a steady state during 120 min of gas perfusion.
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000494:pharmacology*; D002127:Calcium Isotopes; D002415:Cats; D006321:Heart / Q000502:physiology; D007700:Kinetics; D008722:Methods; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism
D002127:Calcium Isotopes; D002118:Calcium