Potentiation of depolarization-induced calcium release from skeletal muscle triads by cyclic ADP-ribose and inositol 1,4,5-trisphosphate.
Two second messengers, cyclic ADP-ribose (cADPR) and inositol 1,4,5-trisphosphate (IP3), potentiated the Ca2+ release from sarcoplasmic reticulum induced by transverse tubular membrane depolarization monitored in a triadic vesicle prepared from skeletal muscle. However, without depolarization they could not trigger the Ca2+ release. On the contrary, only cADPR potentiated caffeine-induced Ca2+ release. Because Ca2+ releases potentiated by cADPR and IP3 were inhibited by 1 microM ruthenium red and 100 microM ryanodine, probably these second messengers potentiated the Ca2+ release through ryanodine receptor Ca2+ channels. These results suggest that in skeletal excitation-contraction coupling, cADPR and IP3 play a role as a potentiator or a modifier in vivo, but both modification pathways are different from each other.
Yamaguchi
N
N
Division of Biophysical Engineering, Graduate School of Engineering Science, Osaka University, Japan. n-yama@bpe.es.osaka-u.ac.jp
Kasai
M
M
D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D036563:Cyclic ADP-Ribose; D004558:Electric Stimulation; D004594:Electrophysiology; D005456:Fluorescent Dyes / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D007700:Kinetics; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits; D012430:Ruthenium Red / Q000494:pharmacology; D012433:Ryanodine / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism
D005456:Fluorescent Dyes; D012430:Ruthenium Red; D036563:Cyclic ADP-Ribose; D012433:Ryanodine; D000246:Adenosine Diphosphate Ribose; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium; D016257:Fura-2