IS NITRIC-OXIDE THE FINAL MEDIATOR REGULATING THE MIGRATING MYOELECTRIC COMPLEX CYCLE

The main objective was to study the role of nitric oxide (NO) in the conversion of migrating myoelectric complexes (MMC) to the irregular electrical activity characteristic of the postprandial state. Both rats and chickens were implanted with electrodes for electromyography in the small intestine. Intravenous infusion of N-G-nitro-L-arginine (L-NNA), a NO synthase inhibitor, induced an organized MMC-like pattern in fed rats. Infusion of sodium nitroprusside, a NO donor, disrupted the MMC, inducing a postprandial-like motor pattern in fasting rats. Similarly, in chickens L-NNA mimicked the fasting pattern, consisting of a shortening of phase II, enlargement of phase III, orad displacement of the origin of the MMC, and an increase in the speed of phase III propagation. An inhibition of NO synthesis seems to be involved in the induction of the fasting motor pattern, whereas an increase of NO mediates the occurrence of the fed pattern. It is suggested that NO might be the final mediator in the control of small intestine motor patterns.