title: Unaffected contractility of diaphragm muscle fibers in humans on mechanical ventilation.
abstract: Several studies have indicated that diaphragm dysfunction develops in patients on mechanical ventilation (MV). Here, we tested the hypothesis that the contractility of sarcomeres, i.e., the smallest contractile unit in muscle, is affected in humans on MV. To this end, we compared diaphragm muscle fibers of nine brain-dead organ donors (cases) that had been on MV for 26 ± 5 h with diaphragm muscle fibers from nine patients (controls) undergoing surgery for lung cancer that had been on MV for less than 2 h. In each diaphragm specimen we determined 1) muscle fiber cross-sectional area in cryosections by immunohistochemical methods and 2) the contractile performance of permeabilized single muscle fibers by means of maximum specific force, kinetics of cross-bridge cycling by rate of tension redevelopment, myosin heavy chain content and concentration, and calcium sensitivity of force of slow-twitch and fast-twitch muscle fibers. In case subjects, we noted no statistically significant decrease in outcomes compared with controls in slow-twitch or fast-twitch muscle fibers. These observations indicate that 26 h of MV of humans is not invariably associated with changes in the contractile performance of sarcomeres in the diaphragm.
authors.affiliation: Departments of Physiology.
authors.forename: Pleuni E
authors.initials: PE
authors.lastname: Hooijman
authors.affiliation: Cardiothoracic Surgery, and.
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Paul
authors.affiliation: Departments of Physiology, Faculty of Science, Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, The Netherlands;
authors.forename: Ger J M
authors.initials: GJ
authors.lastname: Stienen
authors.affiliation: Intensive Care, Vrije Universiteit Medical Center, Amsterdam, The Netherlands;
authors.forename: Albertus
authors.initials: A
authors.lastname: Beishuizen
authors.affiliation: Department of Pulmonary Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands;
authors.forename: Hieronymus W H
authors.initials: HW
authors.lastname: Van Hees
authors.affiliation: Department of Surgery, University of Pennsylvania and Veterans Affairs Medical Center, Philadelphia, Pennsylvania;
authors.forename: Sunil
authors.initials: S
authors.lastname: Singhal
authors.affiliation: Department of Surgery, University of Pennsylvania and Veterans Affairs Medical Center, Philadelphia, Pennsylvania;
authors.forename: Muhammad
authors.initials: M
authors.lastname: Bashir
authors.affiliation: Department of Surgery, University of Pennsylvania and Veterans Affairs Medical Center, Philadelphia, Pennsylvania;
authors.forename: Murat T
authors.initials: MT
authors.lastname: Budak
authors.affiliation: Department of Surgery, University of Pennsylvania and Veterans Affairs Medical Center, Philadelphia, Pennsylvania;
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Morgen
authors.affiliation: Department of Physiology, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania;
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Barsotti
authors.affiliation: Department of Surgery, University of Pennsylvania and Veterans Affairs Medical Center, Philadelphia, Pennsylvania; Gift of Life Donor Program, Philadelphia, Pennsylvania; and.
authors.forename: Sanford
authors.initials: S
authors.lastname: Levine
authors.affiliation: Departments of Physiology, Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona coeno@email.arizona.edu.
authors.forename: Coen A C
authors.initials: CA
authors.lastname: Ottenheijm
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001926:Brain Death / Q000503:physiopathology; D003964:Diaphragm / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch; D018657:Muscle Fibers, Slow-Twitch; D012121:Respiration, Artificial
keywords: contractility; diaphragm; mechanical ventilation; single muscle fiber