title: Spasmogenic effect of platelet activating factor (PAF) on isolated rat stomach fundus strip.
abstract: Platelet activating Factor (PAF) produced an increase in resting tension of isolated rat stomach fundus strips. The spasmogenic effect of a 90 nM dose was equivalent to the contraction to 110 nM acetylcholine (ACh). Tissues exposed once to PAF became refractory to re-challenge with a dose of PAF normally producing maximum contraction (desensitization). PAF desensitized tissues remained responsive to the contraction effects of ACh and KCl (80 mM). Lyso-PAF failed to produce any effect. PAF contraction was dose-dependently antagonized by pretreatment of tissues with the PAF receptor antagonist L-652,731. PAF contractions were not blocked by antagonists of cholinergic, adrenergic, histaminergic, and serotonergic receptors, nor by inhibition of cyclooxygenase. PAF is a potent spasmogen on the isolated rat stomach fundus strip, and this effect is PAF and PAF-receptor specific.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005748:Gastric Fundus / Q000187:drug effects*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D010972:Platelet Activating Factor / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013035:Spasm / Q000139:chemically induced
chemical_list: D010972:Platelet Activating Factor; D001285:Atropine; D000109:Acetylcholine