THE EFFECTS OF PROSTAGLANDINS ON GUINEA‐PIG ISOLATED INTESTINE AND THEIR POSSIBLE CONTRIBUTION TO MUSCLE ACTIVITY AND TONE

Abstract
1 Prostaglandins F and F caused contraction of the longitudinal muscle of both guinea-pig isolated ileum and colon, apparently by acting directly on the muscle and on cholinergic nerves. They had little effect on ileal circular muscle. 2 Prostaglandins E1 and E2 caused contraction of the longitudinal muscle of guinea-pig isolated colon, apparently by acting directly on the muscle and on excitatory nerves which are non-cholinergic. Prostaglandin E1 seems more effective than E2 in stimulating these nerves. 3 It seems likely that prostaglandin release in vitro maintains the tone of the longitudinal muscle of guinea-pig colon, whereas release of a prostaglandin E compound inhibits circular muscle tone.