GTP-binding protein amplifies contractile responses of alpha-toxin-permeabilized uterine smooth muscle to Ca2+.
1. alpha-toxin of Staphylococcus aureus readily permeabilized rat uterine smooth muscle after incubation for a short time. 2. The permeabilized muscle responded to Ca2+ dose-dependently and repeatedly in the same manner. 3. The threshold concentration of Ca2+ for contraction was 0.1-0.3 microM and the maximal contraction was achieved with 1 or 3 microM Ca2+. 4. GTP gamma S or GTP augmented the contractile response to Ca2+. 5. GDP beta S or GDP suppressed the contraction. 6. The role of GTP-binding protein in sensitization of Ca(2+)-induced contractile response of smooth muscle is discussed.
Suga
O
O
Department of Molecular Pharmacology, Meiji College of Pharmacy, Tokyo, Japan.
Oishi
K
K
Uchida
M K
MK
D000818:Animals; D002118:Calcium / Q000493:pharmacokinetics*; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D010539:Permeability / Q000187:drug effects; D051381:Rats; D010738:Type C Phospholipases / Q000494:pharmacology*; D014590:Uterine Contraction / Q000187:drug effects* / Q000502:physiology
D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium