Spasmogenic effects of L-ascorbic acid on the guinea pig isolated ileum preparation

The mechanism of actions of L-ascorbic acid (AA) on the guinea pig isolated ileum wasstudied. AA (neutralized, 10(-3) M) produced a stimulated motility (A effect) and a potentiation in acetylcholine (ACh)-induced contraction (B effect). The A effect showed a tachyphylaxis, and was inhibited by tetrodotoxin, atropine, adenosine, morphine, strychnine, Mg2+, papaverine and glucose- and Ca2+-free medium, but was stimulated by eserine. Thus, AA appears to have not only a direct myogenic effect but also a neurogenic effect by stimulating ACh release from intramural cholinergic nerves.