L-Arginine and melatonin interaction in rat intestinal ischemia--reperfusion.

We investigated the combinative effects of L-arginine and melatonin on the contractile responses of terminal ileum after the intestinal ischemia-reperfusion (I/R), in vivo. Male rats were subjected to mesenteric ischemia (30 min) followed by reperfusion (180 min). We have observed a dramatic decrease in spontaneous basal activity and Ach-induced contractile response. Our data clearly showed that the contractility decrease was ameliorated by L-arginine but not by L-NAME. Melatonin has reversed the inhibition of contractility caused by I/R injury in part. We did not observe an augmentation in the contractility of ileum when we use melatonin and L-arginine in combination, in fact, melatonin decreased the protective effect of L-arginine in intestinal I/R injury.