title: Force-inhibiting effect of Ser/Thr protein phosphatase 2A inhibitors on bovine ciliary muscle.
abstract: Ciliary muscle is a smooth muscle characterized by a rapid response to muscarinic receptor stimulation and sustained contraction. Although it is evident that these contractions are Ca(2+)-dependent, detailed molecular mechanisms are still unknown. In order to elucidate the role of Ser/Thr protein phosphatase 2A (PP2A) in ciliary muscle contraction, we examined the effects of okadaic acid and other PP2A inhibitors on contractions induced by carbachol (CCh) and ionomycin in bovine ciliary muscle strips (BCM). Okadaic acid inhibited ionomycin-induced contraction, while it did not cause significant changes in CCh-induced contraction. Fostriecin showed similar inhibitory effects on the contraction of BCM. On the other hand, rubratoxin A inhibited both ionomycin- and CCh-induced contractions. These results indicated that PP2A was involved at least in ionomycin-induced Ca(2+)-dependent contraction, and that BCM had a unique regulatory mechanism in CCh-induced contraction.
authors.affiliation: Department of Physiology, Asahikawa Medical University, Hokkaido, Japan.
authors.forename: Minori
authors.initials: M
authors.lastname: Ishida
authors.forename: Kosuke
authors.initials: K
authors.lastname: Takeya
authors.forename: Motoi
authors.initials: M
authors.lastname: Miyazu
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Yoshida
authors.forename: Akira
authors.initials: A
authors.lastname: Takai
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002417:Cattle; D002924:Ciliary Body / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D015759:Ionomycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009183:Mycotoxins / Q000494:pharmacology; D019319:Okadaic Acid / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors* / Q000502:physiology*; D011090:Polyenes / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D009183:Mycotoxins; D011090:Polyenes; D011753:Pyrones; C100297:rubratoxins; D019319:Okadaic Acid; D015759:Ionomycin; D002217:Carbachol; D010749:Phosphoprotein Phosphatases; D002118:Calcium; C040313:fostriecin