title: Time course analysis of mechanical ventilation-induced diaphragm contractile muscle dysfunction in the rat.
abstract: Controlled mechanical ventilation (CMV) plays a key role in triggering the impaired diaphragm muscle function and the concomitant delayed weaning from the respirator in critically ill intensive care unit (ICU) patients. To date, experimental and clinical studies have primarily focused on early effects on the diaphragm by CMV, or at specific time points. To improve our understanding of the mechanisms underlying the impaired diaphragm muscle function in response to mechanical ventilation, we have performed time-resolved analyses between 6 h and 14 days using an experimental rat ICU model allowing detailed studies of the diaphragm in response to long-term CMV. A rapid and early decline in maximum muscle fibre force and preceding muscle fibre atrophy was observed in the diaphragm in response to CMV, resulting in an 85% reduction in residual diaphragm fibre function after 9-14 days of CMV. A modest loss of contractile proteins was observed and linked to an early activation of the ubiquitin proteasome pathway, myosin:actin ratios were not affected and the transcriptional regulation of myosin isoforms did not show any dramatic changes during the observation period. Furthermore, small angle X-ray diffraction analyses demonstrate that myosin can bind to actin in an ATP-dependent manner even after 9-14 days of exposure to CMV. Thus, quantitative changes in muscle fibre size and contractile proteins are not the dominating factors underlying the dramatic decline in diaphragm muscle function in response to CMV, in contrast to earlier observations in limb muscles. The observed early loss of subsarcolemmal neuronal nitric oxide synthase activity, onset of oxidative stress, intracellular lipid accumulation and post-translational protein modifications strongly argue for significant qualitative changes in contractile proteins causing the severely impaired residual function in diaphragm fibres after long-term mechanical ventilation. For the first time, the present study demonstrates novel changes in the diaphragm structure/function and underlying mechanisms at the gene, protein and cellular levels in response to CMV at a high temporal resolution ranging from 6 h to 14 days.
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Corpeno
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors.forename: B
authors.initials: B
authors.lastname: Dworkin
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Cacciani
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Salah
authors.affiliation: Department of Chemistry-Biomedical Center, Analytical Chemistry and SciLifeLab, Uppsala University, Sweden.
authors.forename: H-M
authors.initials: HM
authors.lastname: Bergman
authors.affiliation: Department of Biomedical Sciences, University of Padova, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Ravara
authors.affiliation: Department of Biomedical Sciences, University of Padova, Italy CNR-Institute of Neuroscience, Padova section, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Vitadello
authors.affiliation: Department of Biomedical Sciences, University of Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Gorza
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden.
authors.forename: A-M
authors.initials: AM
authors.lastname: Gustafson
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Hedström
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Petersson
authors.affiliation: Department of Physiology, Wayne State University, Detroit, MI, USA.
authors.forename: H-Z
authors.initials: HZ
authors.lastname: Feng
authors.affiliation: Department of Physiology, Wayne State University, Detroit, MI, USA.
authors.forename: J-P
authors.initials: JP
authors.lastname: Jin
authors.affiliation: Japan Synchrotron Radiation Research Institute, Sayo-cho, Sayo-gun, Hyogo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Iwamoto
authors.affiliation: Japan Synchrotron Radiation Research Institute, Sayo-cho, Sayo-gun, Hyogo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yagi
authors.affiliation: Department of Chemistry-Biomedical Center, Analytical Chemistry and SciLifeLab, Uppsala University, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Artemenko
authors.affiliation: Department of Chemistry-Biomedical Center, Analytical Chemistry and SciLifeLab, Uppsala University, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Bergquist
authors.affiliation: Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden lars.larsson@neuro.uu.se.
authors.forename: L
authors.initials: L
authors.lastname: Larsson
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003964:Diaphragm / Q000166:cytology / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D050356:Lipid Metabolism; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000502:physiology; D053580:Muscle Strength; D009218:Myosins / Q000235:genetics / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D012123:Pulmonary Ventilation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D012122:Ventilators, Mechanical / Q000009:adverse effects*
chemical_list: D000199:Actins; D000255:Adenosine Triphosphate; D052248:Nitric Oxide Synthase Type I; D046988:Proteasome Endopeptidase Complex; D009218:Myosins