Actions of Cyclic AMP and Dibutyryl Cyclic AMP on the Electricl and Mechanical Activities of the Cat Small Intestine

Cyclic AMP and dibutyeyl cyclic AMP produced the inhibitory action on the spike activity and contraction of the cat small intestine Beta-stimulants also exhibited the inhibitory action. Caffeine, diprophylline, papaverine and DCI produced the inhibitory effect. The inhibitions caused by caffeine, diprophylline and papaverine were depended on those metabolic action but a part of inhibitory action by papaverine seems to caused by the inhibition of spike activity. The relaxing effects of cyclic AMP and dibutyryl cyclic AMP were not blocked by propranolol and DCI and were potentiated by caffeine and diprophylline. Quiuidine blocked the inhibitory action of noradrenaline, AMP and cyclic AMP. Those findings support the hypothesis that cyclic AMP in cells relates the motility of intestinal smooth muscle. The spike activity was little influenced by exogenously applied cyclic AMP and dibutyryl cyclic AMP. Therefore, the inhibitory action of those agents may due to the inhibition on electrical activity partially.