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Excitation contraction coupling in skeletal muscle: Evidence for a role of slow Ca2+ channels using Ca2+ channel activators and inhibitors in the dihydropyridine series

1985; Elsevier BV; Volume: 129; Issue: 3 Linguagem: Inglês

10.1016/0006-291x(85)91977-1

1090-2104

M Ildefonse, Vincent Jacquemond, O Rougier, J. F. Renaud, Michel Fosset, Michel Lazdunski,

Pain Mechanisms and Treatments

Ca2+ current and tension have been simultaneously recorded from single twitch fibres of the semi-tendinosus of Ranaesculenta in a medium containing a physiological Ca2+ concentration (1.8 mM). Under appropriate conditions it can be shown that tension develops in two phases. The first is rapid and reaches its maximum before activation of the inward Ca2+ current. The second phase is slower and with a time course which appears to be correlated with that of the inward current. Nifedipine, a specific Ca2+ channel inhibitor greatly reduced ICa2+ and the slower component of tension. Bay K8644 a Ca2+ channel activator, which has receptors on T-tubule, increased ICa2+ and the slow component of tension. These results indicate that a slow component of skeletal muscle contraction is related to the inward Ca2+ current flowing through dihydropyridine sensitive voltage-dependent Ca2+ channels.