Oxytocin contracts rat uterine smooth muscle in Ca2(+)-free medium without any phosphorylation of myosin light chain.
Contraction of rat uterine smooth muscle related to phosphorylation state of myosin light chain under various conditions was investigated. In the Ca2(+)-containing medium, both high K+ and oxytocin induced marked contraction of the muscle accompanied by pronounced phosphorylation of myosin light chain. In the Ca2(+)-free medium, although both vanadate and oxytocin induced slight contraction, phosphorylation of myosin light chain was only evident for vanadate but not for oxytocin. It was suggested that another mechanism distinct from myosin light chain phosphorylation might be involved in Ca2(+)-independent contraction of uterine smooth muscle elicited by oxytocin.
Oishi
K
K
Department of Molecular Pharmacology, Meiji College of Pharmacy, Tokyo, Japan.
Takano-Ohmuro
H
H
Minakawa-Matsuo
N
N
Suga
O
O
Karibe
H
H
Kohama
K
K
Uchida
M K
MK
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009218:Myosins / Q000302:isolation & purification / Q000378:metabolism*; D010121:Oxytocin / Q000494:pharmacology*; D010766:Phosphorylation; D051381:Rats; D014590:Uterine Contraction / Q000187:drug effects*; D014599:Uterus / Q000187:drug effects / Q000502:physiology*
D010121:Oxytocin; D004533:Egtazic Acid; D009218:Myosins; D002118:Calcium