No evidence for inositol 1,4,5-trisphosphate-dependent Ca2+ release in isolated fibers of adult mouse skeletal muscle.
The presence and role of functional inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs) in adult skeletal muscle are controversial. The current consensus is that, in adult striated muscle, the relative amount of IP(3)Rs is too low and the kinetics of Ca(2+) release from IP(3)R is too slow compared with ryanodine receptors to contribute to the Ca(2+) transient during excitation-contraction coupling. However, it has been suggested that IP(3)-dependent Ca(2+) release may be involved in signaling cascades leading to regulation of muscle gene expression. We have reinvestigated IP(3)-dependent Ca(2+) release in isolated flexor digitorum brevis (FDB) muscle fibers from adult mice. Although Ca(2+) transients were readily induced in cultured C2C12 muscle cells by (a) UTP stimulation, (b) direct injection of IP(3), or (c) photolysis of membrane-permeant caged IP(3), no statistically significant change in calcium signal was detected in adult FDB fibers. We conclude that the IP(3)-IP(3)R system does not appear to affect global calcium levels in adult mouse skeletal muscle.
Venetian Institute of Molecular Medicine, 35129 Padova, Italy.
Bert
B
Blaauw
Paola
P
Del Piccolo
Laura
L
Rodriguez
Victor-Hugo
VH
Hernandez Gonzalez
Lisa
L
Agatea
Francesca
F
Solagna
Fabio
F
Mammano
Tullio
T
Pozzan
Stefano
S
Schiaffino
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism* / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010782:Photolysis; D014544:Uridine Triphosphate / Q000494:pharmacology
D053496:Inositol 1,4,5-Trisphosphate Receptors; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium; D014544:Uridine Triphosphate