Vanilloid receptor expressed in the sarcoplasmic reticulum of rat skeletal muscle.
Vanilloid receptor subtype 1 (VR1) was cloned as a capsaicin receptor from neuronal cells of dorsal root ganglia. VR1 was subsequently found in a few non-neuronal tissues, including skeletal muscle [Onozawa et al., Tissue distribution of capsaicin receptor in the various organs of rats, Proc. Jpn. Acad. Ser. B 76 (2000) 68-72]. We confirmed the expression of VR1 in muscle cells using the RT-PCR method and Western blot analysis. Immunostaining studies with a confocal microscope and an electron microscope indicated that VR1 was present in the sarcoplasmic reticulum (SR), a store of Ca2+. The SR releases Ca2+ to cause a contraction when a muscle is excited. However, SR still releases a small amount of Ca2+ under relaxed conditions. We found that this leakage was enhanced by capsaicin and was antagonized by capsazepine, a capsaicin blocker, indicating that leakage of Ca2+ occurs through a channel composed of VR1.
Xin
Hong
H
Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan.
Tanaka
Hideyuki
H
Yamaguchi
Maki
M
Takemori
Shigeru
S
Nakamura
Akio
A
Kohama
Kazuhiro
K
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002460:Cell Line; D015870:Gene Expression; D007473:Ion Channels / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D050916:TRPV Cation Channels
D007473:Ion Channels; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; C071423:capsazepine; D002211:Capsaicin; D002118:Calcium