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Nitric oxide regulates migrating motor complex cycling and its postprandial disruption
S K Sarna1, M F Otterson, R P Ryan
1Department of Surgery, Medical College of Wisconsin, Milwaukee.
The American Journal of Physiology
|October 1, 1993
Summary
Nitric oxide (NO) plays a key role in regulating gut motility, specifically the migrating motor complex (MMC) and gastric cyclic motor activity (CMA). NO synthase inhibition disrupts normal gut cycling, affecting fasting and post-meal activity.
Area of Science:
- Gastroenterology
- Neurogastroenterology
- Physiology
Background:
- The migrating motor complex (MMC) is crucial for interdigestive gastrointestinal motility.
- Nonadrenergic noncholinergic (NANC) neurons are implicated in regulating gut functions.
- The precise role of nitric oxide (NO) in MMC cycling and its response to feeding requires further elucidation.
Purpose of the Study:
- To investigate the role of nitric oxide (NO) in regulating the cycling of the migrating motor complex (MMC) during fasting.
- To examine how NO influences the disruption of MMC and gastric cyclic motor activity (CMA) after a meal.
- To identify the specific neurotransmitters involved in NO-mediated gut motility regulation.
Main Methods:
- Intravenous infusion of NO synthase inhibitors, N omega-nitro-L-arginine methyl ester (L-NAME) and N omega-nitro-L-arginine (L-NNA).
- Administration of L-Arginine to assess its effect on NO synthase inhibition.
- Monitoring of gastrointestinal motor activity during fasting and fed states.
- Measurement of mean arterial pressure changes.
Main Results:
- L-NAME infusion induced premature MMC and disrupted MMC cycling, with shorter cycle lengths observed on subsequent days.
- Gastric CMA disruption by L-NAME was longer than MMC disruption in the small intestine.
- L-NAME significantly shortened the duration of meal-induced MMC disruption; L-Arginine blocked these effects.
- Angiotensin II affected blood pressure but not gastrointestinal motor activity.
Conclusions:
- Nitric oxide (NO)-containing nonadrenergic noncholinergic (NANC) neurons are significant regulators of MMC and CMA cycling during fasting and postprandial states.
- NO plays a crucial role in the disruption of gut motility patterns by meals.
- While NO is important, other NANC neurotransmitters may also contribute to inhibiting gut contractions, as evidenced by persistent phase I activity during NO synthase inhibition.