[Effects of food on motility of the small intestine]

It is now well-known that feeding suppresses the phase 3 propagated waves for 2.30 to 10 hours in the small intestine. This finding can be influenced by subject's age, ingestion time and nature of food. The influence of extraluminal factors, i.e. nervous or hormonal, is probable. First, a reduction of jejunal contractions frequency without alteration of their amplitude can be found in the elderly. Second, a late dinner can shorten by 50 per cent the duration of the post-prandial motor profile, which is followed by an irregular activity normally nearly absent and without reappearance of a reduced periodicity of phase 3. In man as in animal, the duration of the post-prandial inhibition is correlated with the caloric content of the meal. At equal colonic content a lipidic meal induces a stronger effect than a glucidic meal which has itself a stronger effect than a protidic one. Fibres eventually increase by 40 to 50 per cent the duration of the post-prandial continuous motor activity in the duodenum, and have, depending on their nature, a variable effect on the jejunum. Digestion and absorption of nutrients also appear to be involved through probable nervous and/or hormonal pathways. In animals, an increased absorption of lipids by addition of bile lengthens the inhibition duration; in man intravenous infusion of a lipidic emulsion can induce a typical post-prandial motor profile. Clinical implications of these results involve at the moment a hypothesis on the physiopathology of diarrhea and artificial, enteral or parenteral, nutrition. On the model of vagotomised patients, it was shown that diarrheic patients exhibited a shorter post-prandial activity. Enteral feeding can interrupt phase 3 on the one hand temporarily and on the other under the conditions of a minimal caloric flow and molecular weight of peptides in case of protidic infusion. Preliminary results with parenteral alimentation were found to be similar, with in particular a strong inhibitory effect of perfusion of lipids.