title: Effect of prostaglandin E2 on rabbit colonic smooth muscle cell contraction.
abstract: Isolated circular smooth muscle cells from the rabbit distal colon were used to study the effect of prostaglandin E2 (PGE2) on bethanechol-stimulated smooth muscle cell contraction. Contraction was expressed as the percentage decrease in mean cell length compared with unstimulated cells. Incubation with different concentrations of PGE2 (10(-10)-10(-6) M) did not cause contraction or relaxation of unstimulated smooth muscle cells. Bethanechol stimulated a dose-dependent contraction that was maximal at 30 s. The threshold for bethanechol-stimulated contraction was 10(-11) M; the ED50 was 10(-10) M; and the maximum contraction (23.0 +/- 1.8%) occurred at 10(-8) M. Preincubation with PGE2 reduced both the efficacy and potency of bethanechol-stimulated contraction. Preincubation with 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or dibutyryl-cAMP reduced the efficacy of bethanechol-stimulated contraction without affecting potency. Increasing concentrations of PGE2 stimulated a dose-dependent increase in the production of intracellular cAMP (P less than 0.05). These studies show that PGE2 inhibits bethanechol-stimulated contraction of isolated colonic circular myocytes and is associated with increased production of intracellular cAMP. There is also a cAMP-independent effect of PGE2 on the potency of bethanechol stimulation.
authors.affiliation: Department of Medicine, Harbor-UCLA Medical Center, Torrance 90509.
authors.forename: H W
authors.initials: HW
authors.lastname: Kao
authors.forename: P E
authors.initials: PE
authors.lastname: Hyman
authors.forename: S E
authors.initials: SE
authors.lastname: Finn
authors.forename: W J
authors.initials: WJ
authors.lastname: Snape
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D018723:Bethanechol; D001626:Bethanechol Compounds / Q000494:pharmacology; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D001626:Bethanechol Compounds; D018723:Bethanechol; D001285:Atropine; D000242:Cyclic AMP; D000254:Sodium-Potassium-Exchanging ATPase; D015232:Dinoprostone; D012413:Rubidium