Tonic inhibition of human small intestinal motility by nitric oxide in children but not in adults.
BACKGROUND
Gastrointestinal motility is dependent on neural influences that largely involve the enteric nervous system (ENS). The main motor patterns that occur in the fasted and fed state are noticeably different in children compared with adults. Although the development of the ENS continues after birth, there is no data on the contractile activity of segments of small intestine from young children. This study was designed to provide data on the development of muscle control by the human ENS with particular attention to acetylcholine (ACh) and nitric oxide (NO) as the primary neurotransmitters of enteric motor neurons, respectively.


METHODS
Small intestinal specimens were obtained from 11 children and six adults undergoing surgery for various diseases. The mechanical activity of the circular muscle was recorded in vitro. The effects of N(ω)-nitro-L-arginine methyl ester hydrochloride, an inhibitor of NO synthesis, and of atropine, an antagonist of muscarinic receptors, were tested on the spontaneous motility and responses to nerve stimulation.


RESULTS
Spontaneous motility was observed in all preparations. Responses to nerve stimulation were identical in child and adult. No tonic cholinergic excitation of small intestinal motility was observed either in child or in adult. Inhibition of NO synthesis induced a major disinhibition of motility in child but not in adult.


CONCLUSIONS
Spontaneous intestinal motility and cholinergic and nitrergic neurotransmission are present from birth. NO provides a tonic inhibition of intestinal motility only in child. Our study indicates that NO may be a major player in shaping the ontogenic development of intestinal motility in human.
Wittmeyer
V
V
Département de Chirurgie et Orthopédie de l'Enfant, Hôpital Jeanne de Flandre, CHRU de Lille, Lille cedex, France.
Merrot
T
T
Mazet
B
B
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001285:Atropine / Q000494:pharmacology; D002648:Child; D004558:Electric Stimulation; D004576:Electromyography; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000187:drug effects* / Q000254:growth & development*; D008297:Male; D008875:Middle Aged; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D018727:Muscarinic Antagonists; D009569:Nitric Oxide; D001285:Atropine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester