Abstract
1. The effects of three glucocorticosteroids, hydrocortisone, methylprednisolone and dexamethasone, as well as two non-steroidal anti-inflammatory agents (NSAIDs) indomethacin and diclofenac sodium were tested in vitro on the spontaneously rhythmic contracting ureteral preparation of the sheep. 2. The NSAIDs and the steroids methylprednisolone (10(-7)-10(-4) M) and dexamethasone (10(-8) - 10(-4) M), dose-dependently inhibited ureteral motility. Hydrocortisone caused a cessation of spontaneous contractions only at the high concentration of 10(-4) M. 3. Pretreatment of ureteral strips with the protein synthesis inhibitor cycloheximide (10(-6) M) abolished the inhibitory action of the corticosteroids on peristalsis, consistent with the suggestion that the action of steroids on the ureter is mediated via the synthesis of the anti-phospholipase protein, lipocortin. 4. The potency of the steroids in descending order was found to be dexamethasone greater than methylprednisolone greater than hydrocortisone.