Biomaterial Database

Effect of the diaphragmatic contraction on lower oesophageal sphincter pressure in man. 1987

R K Mittal, and D F Rochester, and R W McCallum

Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville 22908.

The effect of diaphragmatic contraction and relaxation on the lower oesophageal sphincter (LOS) pressure was studied in 10 healthy volunteers. Pressures in the oesophagus, LOS, and stomach were measured in three phases. Phase I, end tidal expiration; phase II, subjects inspired to total lung capacity (TLC) and kept the airway open (sustained diaphragmatic contraction); and phase III, at TLC subjects relaxed against a closed glottis (diaphragm relaxed). The LOS pressure in phase II was significantly higher than in phase I, while in phase III it was significantly lower compared with phase I. There was a net increase in LOS pressure of 32 mmHg in phase II as compared to phase I. After phase II, as subjects moved into phase III, there was a sudden drop in the LOS pressure. The LOS pressure in phase II correlated with the transdiaphragmatic pressure in a linear fashion. These observations suggest that diaphragmatic contraction in man enhances the LOS pressure and this augmentation of sphincter tone may be a vital component of the antireflux mechanism.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009126	Muscle Relaxation	That phase of a muscle twitch during which a muscle returns to a resting position.	Muscle Relaxations,Relaxation, Muscle,Relaxations, Muscle
D011312	Pressure	A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Pressures
D003964	Diaphragm	The musculofibrous partition that separates the THORACIC CAVITY from the ABDOMINAL CAVITY. Contraction of the diaphragm increases the volume of the thoracic cavity aiding INHALATION.	Respiratory Diaphragm,Diaphragm, Respiratory,Diaphragms,Diaphragms, Respiratory,Respiratory Diaphragms
D004943	Esophagogastric Junction	The area covering the terminal portion of ESOPHAGUS and the beginning of STOMACH at the cardiac orifice.	Gastroesophageal Junction,Gastroesophageal Junctions,Junction, Esophagogastric,Junction, Gastroesophageal,Junctions, Gastroesophageal
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D014109	Total Lung Capacity	The volume of air contained in the lungs at the end of a maximal inspiration. It is the equivalent to each of the following sums: VITAL CAPACITY plus RESIDUAL VOLUME; INSPIRATORY CAPACITY plus FUNCTIONAL RESIDUAL CAPACITY; TIDAL VOLUME plus INSPIRATORY RESERVE VOLUME plus functional residual capacity; or tidal volume plus inspiratory reserve volume plus EXPIRATORY RESERVE VOLUME plus residual volume.	Lung Capacity, Total,Capacities, Total Lung,Capacity, Total Lung,Lung Capacities, Total,Total Lung Capacities