Inositol 1,4,5-trisphosphate-induced contraction in skinned single smooth muscle cells from guinea-pig taenia coli.
Inositol 1,4,5-trisphosphate (IP3) caused a contraction in skinned single smooth muscle cells from the guinea-pig taenia coli. The contractile response to IP3 was rapid (half time less than 5 s), concentration-dependent (0.01-10 microM, EC50; 0.1 microM) and also depended on the concentration of Ca2+ during preloading. IP3 induced a rapid 45Ca2+ release from the skinned single cells which were preloaded with 10(-6) M Ca2+. The contractile response caused by IP3 was not enhanced by simultaneous application of caffeine (25 mM). The inhibitory effect of procaine on IP3-induced contraction was less than that on caffeine-induced contraction. These results suggest that IP3 also plays an important role in the contractile response in smooth muscle cells from guinea-pig taenia coli and that the mechanism of Ca2+ release from intracellular storage sites by IP3 is different from that by caffeine.
Ohata
H
H
Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Maeda
T
T
Momose
K
K
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects*; D011343:Procaine / Q000494:pharmacology; D013403:Sugar Phosphates / Q000494:pharmacology*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D002110:Caffeine; D011343:Procaine; D015544:Inositol 1,4,5-Trisphosphate