The inhibitory effect of ethanol extracts of Boussingaultia gracilis (EBG) has been studied in muscle strips from the rat gastric fundus. When tone was raised by administration of carbachol, EBG concentration dependently relaxed the strips. The inhibitory effects of EBG were markedly reduced by pretreatment with propranolol; pretreatment with phentolamine slightly reduced the effects of EBG. The relaxant effect of EBG was not affected by pretreatment with hexamethonium, alpha-chymotrypsin, L-N-G-nitro-arginine-methyl-ester or methylene blue, These results indicated that EBG relaxed the gastric fundus mainly mediated via a beta-adrenoceptors.
