title: Reflex control of intestinal gas dynamics and tolerance in humans.
abstract: Intestinal transit of gas is normally adapted to the luminal gas load, but in some patients impaired transit may lead to gas retention and symptoms. We hypothesized that intestinal gas transit is regulated by reflex mechanisms released by segmental distension at various gut levels. In 24 healthy subjects, we measured gas evacuation and perception of jejunal gas infusion (12 ml/min) during simultaneous infusion of duodenal lipids mimicking the postprandial caloric load (Intralipid, 1 kcal/min). We evaluated the effects of proximal (duodenal) distension (n = 8), distal (rectal) distension (n = 8), and sham distension, as control (n = 8). Duodenal lipid infusion produced gas retention (366 +/- 106 ml) with low abdominal perception (1.5 +/- 0.8 score). Distension of either the duodenum or rectum during lipid infusion expedited gas transit and prevented retention (-120 +/- 164 and -124 +/- 162 ml retention, respectively; P < 0.05 vs. control). However, the tolerance to the intestinal gas load differed markedly, depending on the site of distension; perception remained low during rectal distension (2.6 +/- 0.7 score; not significant vs. control) but increased during duodenal distension (4.4 +/- 0.7 score; P < 0.05 vs. control). We conclude that focal gut distension, either at proximal or distal sites, accelerates gas transit, but the symptomatic response depends on the site of stimulation.
authors.affiliation: Digestive System Research Unit, Hospital General Vall d'Hebron, Autonomous University of Barcelona, 08035 Barcelona, Spain.
authors.forename: Hermann
authors.initials: H
authors.lastname: Harder
authors.forename: Jordi
authors.initials: J
authors.lastname: Serra
authors.forename: Fernando
authors.initials: F
authors.lastname: Azpiroz
authors.forename: Juan-R
authors.initials: JR
authors.lastname: Malagelada
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology; D000285:Administration, Rectal; D000328:Adult; D001003:Anal Canal / Q000502:physiology; D004386:Duodenum / Q000502:physiology; D002149:Energy Intake / Q000502:physiology; D005260:Female; D005740:Gases / Q000378:metabolism*; D006801:Humans; D007422:Intestines / Q000502:physiology*; D007583:Jejunum / Q000502:physiology; D008055:Lipids / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009129:Muscle Tonus / Q000502:physiology; D010465:Perception / Q000502:physiology; D012018:Reflex / Q000502:physiology*
chemical_list: D005740:Gases; D008055:Lipids