Excitation contraction coupling in skeletal muscle: evidence for a role of slow Ca2+ channels using Ca2+ channel activators and inhibitors in the dihydropyridine series.
Ca2+ current and tension have been simultaneously recorded from single twitch fibres of the semi-tendinosus of Rana esculenta 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.
M
M
Ildefonse
V
V
Jacquemond
O
O
Rougier
J F
JF
Renaud
M
M
Fosset
M
M
Lazdunski
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D007473:Ion Channels / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects*; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology; D011893:Rana esculenta; D013997:Time Factors
D002121:Calcium Channel Blockers; D007473:Ion Channels; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine; D002118:Calcium