title: The possible role of intracellular Ca2+-stores in the rhythm-inotropic relationship of frog heart muscle (a simulation study).
abstract: The hypothesis that intracellular calcium stores play an essential role in determining force-frequency relationships of frog myocardium was tested quantitatively. A simplified mathematical model of excitation-contraction coupling in frog heart muscle was developed and its behaviour under various patterns of stimulation was analysed by means of computer simulation. The model represents a system of ordinary differential equations for individual fluxes within the cell Ca2+-recirculation system and includes a one-compartmental intracellular pool as opposed to the two-compartmental structure of the mammalian sarcoplasmic reticulum (Kaufmann et al. 1974). The behaviour of the model is consistent with available experimental data concerning the basic rhythm-inotropic characteristics of amphibian myocardium and offers some evidence in favour of the basic concept. Within the framework of the proposed model the staircase phenomena in amphibia were accounted for and the impact of different intracellular Ca-movements on the resulting contractile response and rhythm-inotropic phenomena was elucidated.
mesh_terms: D000818:Animals; D001001:Anura; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D004594:Electrophysiology; D008433:Mathematics; D008954:Models, Biological; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism
chemical_list: D002118:Calcium