VARIATION OF INTRACELLULAR CA2+ FOLLOWING CA2+ CURRENT IN HEART A Theoretical Study of Ionic Diffusion Inside a Cylindrical Cell

Rodolphe Fischmeister (1) , Magda Horackova

1 CARPAT - Signalisation et physiopathologie cardiovasculaire

The variation in the concentration of a diffusing substance inside a cylindrical cell submitted to a time-dependent flux at the sarcolemmal membrane was studied theoretically. An application was derived to estimate the local modifications of intracellular free Ca2+ concentration ([Ca2+ ] j) induced by the slow inward Ca2+ current (ICa) in frog heart. During a 0 mV voltage clamp depolarization, [Ca2"] i at the inner side of the membrane rises earlier and faster than [Ca2" at the center of the cell. The binding of intracellular Ca2" to specific sites enhances the deviation between the two concentrations and may generate an accumulation-depletion process of Ca2" near the membrane. However, it also decreases the overall [Ca2 ] j. The relatively slow diffusion of sarcoplasmic Ca2" does not significantly affect the kinetics of ICa through a modification in the Ca2" gradient across the membrane.

Domains: Life Sciences [q-bio]; Human health and pathology; Cardiology and cardiovascular system

Rodolphe Fischmeister, Magda Horackova. VARIATION OF INTRACELLULAR CA2+ FOLLOWING CA2+ CURRENT IN HEART A Theoretical Study of Ionic Diffusion Inside a Cylindrical Cell. Biophysical Journal, 1983, 41 (3), pp.341-8. ⟨10.1016/S0006-3495(83)84445-2⟩. ⟨hal-03618979⟩