Rapid cooling-induced contractures in rat skinned skeletal muscle fibres originate from sarcoplasmic reticulum Ca2+ release through ryanodine and inositol trisphosphate receptors.
Previous reports have shown that cooling striated muscles induces contractile responses that are related to Ca2+ release from the sarcoplasmic reticulum. However, the effect of cooling has generally been studied in the presence of pharmacological agents that potentiate rapid cooling-induced contractures. The present study shows that in saponin-skinned rat skeletal muscle preparations, a drop in temperature from 22 degrees C to 2 degrees C per se induces a contracture which relaxes on return to 22 degrees C. In fast-twitch fibres, rapid cooling-induced contractures are fully blocked by ryanodine, an inhibitor of ryanodine receptors. By contrast, in slow-twitch fibres, ryanodine partially inhibits the rapid cooling-induced contractile response, leaving a residual tension that dissipates after application of inositol 1,4,5-trisphosphate (InsP3). At low concentrations, heparin, an inhibitor of InsP3 receptors, decreases rapid cooling-induced contractures in both types of muscle. The present results suggest that in skeletal muscle, rapid cooling-induced contractures are due to both ryanodine-sensitive and InsP3-sensitive Ca2+ release from the sarcoplasmic reticulum.
Talon
S
S
Laboratoire de Physiologie Générale, EP CNRS 1593, Faculté des Sciences et des Techniques, Nantes, France.
Huchet-Cadiou
C
C
Léoty
C
C
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D003080:Cold Temperature; D003286:Contracture / Q000209:etiology*; D006493:Heparin / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008297:Male; D018656:Muscle Fibers, Fast-Twitch; D018485:Muscle Fibers, Skeletal; D018657:Muscle Fibers, Slow-Twitch; D018482:Muscle, Skeletal; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000502:physiology*; D012433:Ryanodine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology*; D012503:Saponins / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D019837:Ryanodine Receptor Calcium Release Channel; D012503:Saponins; D012433:Ryanodine; D015544:Inositol 1,4,5-Trisphosphate; D006493:Heparin; D002118:Calcium