A modulating role of prostaglandins in responses of guinea-pig isolated ileum to various agonists.

Small doses of prostaglandin E2 (0.3, 0.6 and 0.9 ng/ml) and prostaglandin F2alpha (0.25, 0.5 and 0.75 ng/ml) significantly potentiated the responses of the guinea-pig isolated ileum to cholinergic substances, i.e. acetylcholine, methacholine, carbachol and pilocarpine. All substances were applied from the serosal surface of the guinea-pig isolated ileum. The greatest potentiation of carbachol effect was obtained, and the smallest was the potentiation of pilocarpine effect. The same small doses or prostaglandins E2 and F2alpha did not influence the response of the guinea-pig isolated ileum to histamine and nicotine.