RESUMO
The effects of vitamin C and acetylcholine on the smooth muscle of rat stomach were compared after neomycin-induced blockade of phosphatidylinositol metabolism. The cumulative curves of dose-dependent responses showed a non-competitive antagonism between vitamin C and neomycin. On the other hand, the antagonism between acetylcholine and neomycin was of a mixed, competitive-non-competitive type. The results of the experiments suggest the conclusion that a normal metabolism of phosphatidylinositol controlling calcium transport into the cells is necessary for the stimulating effect of vitamin C on the contractions of the smooth muscles in the digestive tract.
Assuntos
Ácido Ascórbico/farmacologia , Contração Muscular/efeitos dos fármacos , Neomicina/farmacologia , Estômago/efeitos dos fármacos , Acetilcolina/farmacologia , Animais , Relação Dose-Resposta a Droga , Antagonismo de Drogas , Técnicas In Vitro , Músculo Liso/efeitos dos fármacos , Ratos , Ratos EndogâmicosRESUMO
The action of L-ascorbic acid (AA) on the isolated rat stomach fundus and guinea pig ileum was studied. AA induced contractions of these organs and potentiated the effect of ACh and PGE2. The contractile effect of AA was potentiated by eserine and inhibited by atropine. Dose-response relations suggest a stimulatory effect of AA on the muscarinic receptor.
