title: The effects of phenylbutazone on acetylcholine-initiated contractions of gastric muscularis muscle of Bufo marinus.
abstract: We have investigated the effects of phenylbutazone (PBZ), a potent prostaglandin (PG) synthesis inhibitor, on the acetylcholine (ACh)-initiated contractions of isolated gastric muscularis muscle of Bufo marinus. Two types of contractions were identified: tonic contractions and spontaneous contractions. The challenging dose of ACh (1.0 X 10(-4)M) was fixed at the level eliciting optimum contractions of the preparation while the dose of PBZ was varied between 0-5.0 X 10(-4)M. PBZ dose of 1.0 X 10(-4)M suppressed the spontaneous contractions but had no noticeable effect on the tonic contractions. To further elucidate the mechanism through which PBZ suppressed the spontaneous contractions, prostaglandin E2 (PGE2) (10(-7)M) was used to reverse the suppression induced by PBZ (5.0 X 10(-5)M). We concluded that PGE2 plays a part in the manifestation of the cholinergic-initiated contractions of the muscularis muscle of Bufo marinus and the effects of PBZ can be surmounted by administration of PGE2 exogenously.
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors*; D000818:Animals; D002024:Bufo marinus; D015232:Dinoprostone; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010653:Phenylbutazone / Q000494:pharmacology*; D011458:Prostaglandins E / Q000502:physiology
chemical_list: D011458:Prostaglandins E; D010653:Phenylbutazone; D015232:Dinoprostone; D000109:Acetylcholine