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Intensive Care Unit Acquired Weakness Is Associated with Rapid Changes to Skeletal Muscle Proteostasis. Cells 2022; 11:cells11244005. [PMID: 36552769 PMCID: PMC9776723 DOI: 10.3390/cells11244005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
Intensive care unit (ICU)-acquired weakness is a frequent consequence of critical illness that impacts both the limb and respiratory muscles. The cause of ICU-acquired weakness is multifactorial, but both prolonged limb muscle inactivity and mechanical ventilation are risk factors for muscle wasting, which predisposes ICU patients to both short-term complications and long-term disabilities resulting from muscle weakness. Unfortunately, the current research does not provide a detailed understanding of the cellular etiology of ICU-acquired weakness, and no standard treatment exists. Therefore, improving knowledge of the mechanisms promoting muscle atrophy in critically ill patients is essential to developing therapeutic strategies to protect against ICU-induced skeletal muscle wasting. To advance our understanding of the mechanism(s) responsible for ICU-acquired weakness, we tested the hypothesis that ICU-induced muscle inactivity promotes a rapid decrease in anabolic signaling/protein synthesis and accelerates proteolysis in both limb and respiratory muscles. To investigate ICU-induced changes in skeletal muscle proteostasis, adult Sprague Dawley rats were anesthetized and mechanically ventilated for 12 h to simulate ICU care. Measurements of anabolic signaling, protein synthesis, and proteolytic activity in the limb muscles (plantaris and soleus) and respiratory muscles (parasternal and intercostal) revealed ICU-induced reductions in both anabolic signaling (i.e., AKT/mTOR pathway) and muscle protein synthesis. Moreover, simulated ICU care resulted in increased biomarkers of accelerated proteolysis in both limb and respiratory muscles. These novel findings reveal that disturbances in limb and respiratory muscle proteostasis occur rapidly during ICU-induced muscle inactivity, irrespective of the muscle function or muscle fiber type.
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Yoshihara T, Deminice R, Hyatt HW, Ozdemir M, Nguyen BL, Powers SK. Angiotensin 1-7 protects against ventilator-induced diaphragm dysfunction. Clin Transl Sci 2021; 14:1512-1523. [PMID: 33742769 PMCID: PMC8301547 DOI: 10.1111/cts.13015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/29/2021] [Accepted: 02/20/2021] [Indexed: 12/24/2022] Open
Abstract
Mechanical ventilation (MV) is a life‐saving instrument used to provide ventilatory support for critically ill patients and patients undergoing surgery. Unfortunately, an unintended consequence of prolonged MV is the development of inspiratory weakness due to both diaphragmatic atrophy and contractile dysfunction; this syndrome is labeled ventilator‐induced diaphragm dysfunction (VIDD). VIDD is clinically important because diaphragmatic weakness is an important contributor to problems in weaning patients from MV. Investigations into the pathogenesis of VIDD reveal that oxidative stress is essential for the rapid development of VIDD as redox disturbances in diaphragm fibers promote accelerated proteolysis. Currently, no standard treatment exists to prevent VIDD and, therefore, developing a strategy to avert VIDD is vital. Guided by evidence indicating that activation of the classical axis of the renin‐angiotensin system (RAS) in diaphragm fibers promotes oxidative stress and VIDD, we hypothesized that activation of the nonclassical RAS signaling pathway via angiotensin 1‐7 (Ang1‐7) will protect against VIDD. Using an established animal model of prolonged MV, our results disclose that infusion of Ang1‐7 protects the diaphragm against MV‐induced contractile dysfunction and fiber atrophy in both fast and slow muscle fibers. Further, Ang1‐7 shielded diaphragm fibers against MV‐induced mitochondrial damage, oxidative stress, and protease activation. Collectively, these results reveal that treatment with Ang1‐7 protects against VIDD, in part, due to diminishing oxidative stress and protease activation. These important findings provide robust evidence that Ang1‐7 has the therapeutic potential to protect against VIDD by preventing MV‐induced contractile dysfunction and atrophy of both slow and fast muscle fibers.
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Affiliation(s)
- Toshinori Yoshihara
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.,Graduate School of Health and Sports Science, Juntendo University, Inzai, Japan
| | - Rafael Deminice
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.,Department of Physical Education, State University of Londrina, Londrina, Brazil
| | - Hayden W Hyatt
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
| | - Mustafa Ozdemir
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
| | - Branden L Nguyen
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
| | - Scott K Powers
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
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Hyatt HW, Ozdemir M, Yoshihara T, Nguyen BL, Deminice R, Powers SK. Calpains play an essential role in mechanical ventilation-induced diaphragmatic weakness and mitochondrial dysfunction. Redox Biol 2020; 38:101802. [PMID: 33279868 PMCID: PMC7724197 DOI: 10.1016/j.redox.2020.101802] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 02/07/2023] Open
Abstract
Mechanical ventilation (MV) is a life-saving intervention for many critically ill patients. Unfortunately, an unintended consequence of prolonged MV is the rapid development of diaphragmatic atrophy and contractile dysfunction, known as ventilator-induced diaphragm dysfunction (VIDD). Although the mechanism(s) responsible for VIDD are not fully understood, abundant evidence reveals that oxidative stress leading to the activation of the major proteolytic systems (i.e., autophagy, ubiquitin-proteasome, caspase, and calpain) plays a dominant role. Of the proteolytic systems involved in VIDD, calpain has received limited experimental attention due to the longstanding dogma that calpain plays a minor role in inactivity-induced muscle atrophy. Guided by preliminary experiments, we tested the hypothesis that activation of calpains play an essential role in MV-induced oxidative stress and the development of VIDD. This premise was rigorously tested by transgene overexpression of calpastatin, an endogenous inhibitor of calpains. Animals with/without transfection of the calpastatin gene in diaphragm muscle fibers were exposed to 12 h of MV. Results confirmed that overexpression of calpastatin barred MV-induced activation of calpain in diaphragm fibers. Importantly, deterrence of calpain activation protected the diaphragm against MV-induced oxidative stress, fiber atrophy, and contractile dysfunction. Moreover, prevention of calpain activation in the diaphragm forstalled MV-induced mitochondrial dysfunction and prevented MV-induced activation of caspase-3 along with the transcription of muscle specific E3 ligases. Collectively, these results support the hypothesis that calpain activation plays an essential role in the early development of VIDD. Further, these findings provide the first direct evidence that calpain plays an important function in inactivity-induced mitochondrial dysfunction and oxidative stress in skeletal muscle fibers. Inhibiting calpains during mechanical ventilation protects the diaphragm. Calpains play an important role in muscle atrophy and contractile dysfunction. Calpain inhibition during mechanical ventilation prevents mitochondrial dysfunction. Calpain-cleaved molecules may play important signaling roles. Calpain activation cross-talks with other proteolytic systems.
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Affiliation(s)
- Hayden W Hyatt
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
| | - Mustafa Ozdemir
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA; Department of Exercise and Sport Sciences, Hacettepe University, Ankara, Turkey
| | - Toshinori Yoshihara
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA; Department of Exercise Physiology, Juntendo University, Tokyo, Japan
| | - Branden L Nguyen
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - Rafael Deminice
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA; Department of Physical Education, State University of Londrina, Londrina, Brazil
| | - Scott K Powers
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
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Abstract
The vulnerability of early fish stages represents a critical bottleneck for fish recruitment; therefore, it is essential to understand how climate change affects their physiology for more sustainable management of fisheries. Here, we investigated the effects of warming (OW; +4 °C) and acidification (OA; ΔpH = 0.5) on the heart and oxygen consumption rates, metabolic enzymatic machinery—namely citrate synthase (CS), lactate dehydrogenase (LDH), and ß-hydroxyacyl CoA dehydrogenase (HOAD), of seabream (Sparus aurata) larvae (fifteen days after hatch). Oxygen consumption and heart rates showed a significant increase with rising temperature, but decreased with pCO2. Results revealed a significant increase of LDH activity with OW and a significant decrease of the aerobic potential (CS and HOAD activity) of larvae with OA. In contrast, under OA, the activity levels of the enzyme LDH and the LDH:CS ratio indicated an enhancement of anaerobic pathways. Although such a short-term metabolic strategy may eventually sustain the basic costs of maintenance, it might not be adequate under the future chronic ocean conditions. Given that the potential for adaptation to new forthcoming conditions is yet experimentally unaccounted for this species, future research is essential to accurately predict the physiological performance of this commercially important species under future ocean conditions.
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Ikegami T, Ji M, Fujimura N, Suneby Jagers JV, Kieser TM, Easton PA. Costal and crural diaphragm function during sustained hypoxia in awake canines. J Appl Physiol (1985) 2019; 126:1117-1128. [PMID: 30730807 DOI: 10.1152/japplphysiol.00242.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In humans and other mammals, isocapnic hypoxia sustained for 20-60 min exhibits a biphasic ventilation pattern: initial increase followed by a significant ventilatory decline ("roll-off") to a lesser intermediate plateau. During sustained hypoxia, the mechanical action and activity of the diaphragm have not been studied; thus we assessed diaphragm function in response to hypoxic breathing. Thirteen spontaneously breathing awake canines were exposed to moderate levels of sustained isocapnic hypoxia lasting 20-25 min (80 ± 2% pulse oximeter oxygen saturation). Breathing pattern and changes in muscle length and electromyogram (EMG) activity of the costal and crural diaphragm were continuously recorded. Mean tidal shortening and EMG activity of the costal and crural diaphragm exhibited an overall biphasic pattern, with initial brisk increase followed by a significant decline (P < 0.01). Although costal and crural shortening did not differ significantly with sustained hypoxia, this equivalence in segmental shortening occurred despite distinct and differing EMG activities of the costal and crural segments. Specifically, initial hypoxia elicited a greater costal EMG activity compared with crural (P < 0.05), whereas sustained hypoxia resulted in a lesser crural EMG decline/attenuation than costal (P < 0.05). We conclude that sustained isocapnic hypoxia elicits a biphasic response in both ventilation and diaphragmatic function and there is clear differential activation and contribution of the two diaphragmatic segments. This different diaphragm segmental action is consistent with greater neural activation of costal diaphragm during initial hypoxia, then preferential sparing of crural activation as hypoxia is sustained. NEW & NOTEWORTHY In humans and other mammals, during isocapnic hypoxia sustained for 20-60 min ventilation exhibits a biphasic pattern: initial increase followed by significant ventilatory decline ("roll-off"). During sustained hypoxia, the function of the diaphragm is unknown. This study demonstrates that the diaphragm reveals a biphasic action during the time-dependent hypoxic "roll-off" in ventilation. These results also highlight that the two diaphragm segments, costal and crural, show differing, distinctive contributions to diaphragm function during sustained hypoxia.
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Affiliation(s)
- Tetsunori Ikegami
- Department of Emergency Medicine, Kurashiki Central Hospital, Miwa, Kurashiki, Okayama , Japan
| | - Michael Ji
- Department of Critical Care Medicine, University of Calgary , Calgary, Alberta , Canada
| | - Naoyuki Fujimura
- Department of Anesthesiology, St. Mary's Hospital , Kurume, Fukuoka , Japan
| | - Jenny V Suneby Jagers
- Department of Critical Care Medicine, University of Calgary , Calgary, Alberta , Canada
| | - Teresa M Kieser
- Department of Critical Care Medicine, University of Calgary , Calgary, Alberta , Canada
| | - Paul A Easton
- Department of Critical Care Medicine, University of Calgary , Calgary, Alberta , Canada
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Zambelli V, Sigurtà A, Rizzi L, Zucca L, Delvecchio P, Bresciani E, Torsello A, Bellani G. Angiotensin-(1-7) exerts a protective action in a rat model of ventilator-induced diaphragmatic dysfunction. Intensive Care Med Exp 2019; 7:8. [PMID: 30659381 PMCID: PMC6338614 DOI: 10.1186/s40635-018-0218-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 12/25/2018] [Indexed: 12/11/2022] Open
Abstract
Background Ventilator-induced diaphragmatic dysfunction (VIDD) is a common event during mechanical ventilation (MV) leading to rapid muscular atrophy and contractile dysfunction. Recent data show that renin-angiotensin system is involved in diaphragmatic skeletal muscle atrophy after MV. In particular, angiotensin-II can induce marked diaphragm muscle wasting, whereas angiotensin-(1–7) (Ang-(1–7)) could counteract this activity. This study was designed to evaluate the effects of the treatment with Ang-(1–7) in a rat model of VIDD with neuromuscular blocking agent infusion. Moreover, we studied whether the administration of A-779, an antagonist of Ang-(1–7) receptor (Mas), alone or in combination with PD123319, an antagonist of AT2 receptor, could antagonize the effects of Ang-(1–7). Methods Sprague-Dawley rats underwent prolonged MV (8 h), while receiving an iv infusion of sterile saline 0.9% (vehicle) or Ang-(1–7) or Ang-(1–7) + A-779 or Ang-(1–7) + A-779 + PD123319. Diaphragms were collected for ex vivo contractility measurement (with electric stimulation), histological analysis, quantitative real-time PCR, and Western blot analysis. Results MV resulted in a significant reduction of diaphragmatic contractility in all groups of treatment. Ang-(1–7)-treated rats showed higher muscular fibers cross-sectional area and lower atrogin-1 and myogenin mRNA levels, compared to vehicle treatment. Treatment with the antagonists of Mas and Ang-II receptor 2 (AT2R) caused a significant reduction of muscular contractility and an increase of atrogin-1 and MuRF-1 mRNA levels, not affecting the cross-sectional fiber area and myogenin mRNA levels. Conclusions Systemic Ang-(1–7) administration during MV exerts a protective role on the muscular fibers of the diaphragm preserving muscular fibers anatomy, and reducing atrophy. The involvement of Mas and AT2R in the mechanism of action of Ang-(1–7) still remains controversial.
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Affiliation(s)
- Vanessa Zambelli
- Department of Medicine, University of Milano-Bicocca, Monza, Italy
| | - Anna Sigurtà
- Anesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy
| | - Laura Rizzi
- Department of Medicine, University of Milano-Bicocca, Monza, Italy
| | - Letizia Zucca
- Department of Medicine, University of Milano-Bicocca, Monza, Italy
| | - Paolo Delvecchio
- Department of Medicine, University of Milano-Bicocca, Monza, Italy
| | - Elena Bresciani
- Department of Medicine, University of Milano-Bicocca, Monza, Italy
| | - Antonio Torsello
- Department of Medicine, University of Milano-Bicocca, Monza, Italy
| | - Giacomo Bellani
- Department of Medicine, University of Milano-Bicocca, Monza, Italy.
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Increased SOD2 in the diaphragm contributes to exercise-induced protection against ventilator-induced diaphragm dysfunction. Redox Biol 2018; 20:402-413. [PMID: 30414534 PMCID: PMC6226598 DOI: 10.1016/j.redox.2018.10.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/04/2018] [Accepted: 10/08/2018] [Indexed: 01/22/2023] Open
Abstract
Mechanical ventilation (MV) is a life-saving intervention for many critically ill patients. Unfortunately, prolonged MV results in rapid diaphragmatic atrophy and contractile dysfunction, collectively termed ventilator-induced diaphragm dysfunction (VIDD). Recent evidence reveals that endurance exercise training, performed prior to MV, protects the diaphragm against VIDD. While the mechanism(s) responsible for this exercise-induced protection against VIDD remain unknown, increased diaphragm antioxidant expression may be required. To investigate the role that increased antioxidants play in this protection, we tested the hypothesis that elevated levels of the mitochondrial antioxidant enzyme superoxide dismutase 2 (SOD2) is required to achieve exercise-induced protection against VIDD. Cause and effect was investigated in two ways. First, we prevented the exercise-induced increase in diaphragmatic SOD2 via delivery of an antisense oligonucleotide targeted against SOD2 post-exercise. Second, using transgene overexpression of SOD2, we determined the effects of increased SOD2 in the diaphragm independent of exercise training. Results from these experiments revealed that prevention of the exercise-induced increases in diaphragmatic SOD2 results in a loss of exercise-mediated protection against MV-induced diaphragm atrophy and a partial loss of protection against MV-induced diaphragmatic contractile dysfunction. In contrast, transgenic overexpression of SOD2 in the diaphragm, independent of exercise, did not protect against MV-induced diaphragmatic atrophy and provided only partial protection against MV-induced diaphragmatic contractile dysfunction. Collectively, these results demonstrate that increased diaphragmatic levels of SOD2 are essential to achieve the full benefit of exercise-induced protection against VIDD. Prolonged mechanical ventilation results in diaphragmatic weakness which is labeled as ventilator-induced diaphragm dysfunction (VIDD). Endurance exercise training performed prior to mechanical ventilation protects the diaphragm against VIDD. Preventing exercise-induced increases of superoxide dismutase 2 (SOD2) in the diaphragm partially abolishes exercise protection against VIDD. Transgenic overexpression of SOD2 in the diaphragm provides only partial protection against VIDD. We conclude that increases in SOD2 abundance in the diaphragm contributes to the exercise-induced protection against VIDD.
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Smuder AJ, Falk DJ, Sollanek KJ, Nelson WB, Powers SK. Delivery of recombinant adeno-associated virus vectors to rat diaphragm muscle via direct intramuscular injection. Hum Gene Ther Methods 2013; 24:364-71. [PMID: 24006956 PMCID: PMC3869534 DOI: 10.1089/hgtb.2013.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 09/04/2013] [Indexed: 01/14/2023] Open
Abstract
The diaphragm is the most important inspiratory muscle in all mammals, and ventilatory insufficiency caused by diaphragm dysfunction is the leading cause of morbidity and mortality in many genetic and acquired diseases affecting skeletal muscle. Currently, pharmacological inhibitors, genetically modified animals, and invasive procedures are used to study disorders affecting the diaphragm. However, these methodologies can be problematic because of off-target drug effects and the possible nonphysiological consequences of lifelong genetic alterations. Therefore, alternative methods to study this important respiratory muscle are needed. To resolve this, we have developed a methodology to deliver recombinant adeno-associated virus (rAAV) vectors to the rat diaphragm via direct intramuscular injection. We hypothesized that by direct injection of rAAV into the muscle we can selectively target the diaphragm and establish a novel experimental method for studying signaling pathways and also provide a strategy for effectively using rAAV to protect the diaphragm against disease. This report describes the methods and evidence to support the use of rAAV as a therapeutic intervention to study rat diaphragm biology during conditions that promote diaphragm dysfunction.
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Affiliation(s)
- Ashley J. Smuder
- Department of Applied Physiology and Kinesiology, Center for Exercise Science, University of Florida, Gainesville, FL 32611
| | - Darin J. Falk
- Department of Pediatrics, Powell Gene Therapy Center, University of Florida, Gainesville, FL 32611
| | - Kurt J. Sollanek
- Department of Applied Physiology and Kinesiology, Center for Exercise Science, University of Florida, Gainesville, FL 32611
| | - W. Bradley Nelson
- Department of Applied Physiology and Kinesiology, Center for Exercise Science, University of Florida, Gainesville, FL 32611
| | - Scott K. Powers
- Department of Applied Physiology and Kinesiology, Center for Exercise Science, University of Florida, Gainesville, FL 32611
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Powers SK, Wiggs MP, Sollanek KJ, Smuder AJ. Ventilator-induced diaphragm dysfunction: cause and effect. Am J Physiol Regul Integr Comp Physiol 2013; 305:R464-77. [DOI: 10.1152/ajpregu.00231.2013] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mechanical ventilation (MV) is used clinically to maintain gas exchange in patients that require assistance in maintaining adequate alveolar ventilation. Common indications for MV include respiratory failure, heart failure, drug overdose, and surgery. Although MV can be a life-saving intervention for patients suffering from respiratory failure, prolonged MV can promote diaphragmatic atrophy and contractile dysfunction, which is referred to as ventilator-induced diaphragm dysfunction (VIDD). This is significant because VIDD is thought to contribute to problems in weaning patients from the ventilator. Extended time on the ventilator increases health care costs and greatly increases patient morbidity and mortality. Research reveals that only 18–24 h of MV is sufficient to develop VIDD in both laboratory animals and humans. Studies using animal models reveal that MV-induced diaphragmatic atrophy occurs due to increased diaphragmatic protein breakdown and decreased protein synthesis. Recent investigations have identified calpain, caspase-3, autophagy, and the ubiquitin-proteasome system as key proteases that participate in MV-induced diaphragmatic proteolysis. The challenge for the future is to define the MV-induced signaling pathways that promote the loss of diaphragm protein and depress diaphragm contractility. Indeed, forthcoming studies that delineate the signaling mechanisms responsible for VIDD will provide the knowledge necessary for the development of a pharmacological approach that can prevent VIDD and reduce the incidence of weaning problems.
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Affiliation(s)
- Scott K. Powers
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Michael P. Wiggs
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Kurt J. Sollanek
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Ashley J. Smuder
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
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Oliveira ADSB, Costa LB, Assis TDO, Mota DLD, França EÉTD, Araújo Filho JCD, Rosas STP, Medeiros PLD. Effects of controlled and pressure support mechanical ventilation on rat diaphragm muscle. Acta Cir Bras 2013; 27:109-16. [PMID: 22378364 DOI: 10.1590/s0102-86502012000200003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 12/20/2011] [Indexed: 11/22/2022] Open
Abstract
PURPOSE The objective of this study was to analyze the effects of Pressure Controlled Ventilation mode (PCV-C) and PSV mode in diaphragm muscle of rats. METHODS Wistar rats (n=18) were randomly assigned to the control group or to receive 6 hours of PCV and PSV. After this period, animals were euthanized and their diaphragms were excised, frozen in liquid nitrogen and stored in at -80º C for further histomorphometric analysis. RESULTS Results showed a 15% decrease in cross-sectional area of muscle fibers on the PCV-C group when compared to the control group (p<0.001) and by 10% when compared to the PSV group (p<0.05). Minor diameter was decreased in PCV-C group by 9% when compared with the control group (p<0.001) and by 6% when compared to the PSV group (p<0.05). When myonuclear area was analyzed, a 16% decrease was observed in the PCV-C group when compared to the PSV group (p<0.05). No significant difference between the groups was observed in myonuclear perimeter (p>0.05). CONCLUSION Short-term controlled mechanical ventilation seems to lead to muscular atrophy in diaphragm fibers. The PSV mode may attenuate the effects of VIDD.
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Cross-talk between the calpain and caspase-3 proteolytic systems in the diaphragm during prolonged mechanical ventilation. Crit Care Med 2012; 40:1857-63. [PMID: 22487998 DOI: 10.1097/ccm.0b013e318246bb5d] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Diaphragmatic weakness, due to both atrophy and contractile dysfunction, is a well-documented response following prolonged mechanical ventilation. Evidence indicates that activation of the proteases calpain and caspase-3 is essential for mechanical ventilation-induced diaphragmatic weakness to occur. We tested the hypothesis that a regulatory cross-talk exists between calpain and caspase-3 in the diaphragm during prolonged mechanical ventilation. To test this prediction, we determined whether selective pharmacological inhibition of calpain would prevent activation of caspase-3 and conversely whether selective inhibition of caspase-3 would abate calpain activation. DESIGN Animal study. SETTING University Research Laboratory. SUBJECTS Female Sprague-Dawley rats. INTERVENTIONS Animals were randomly divided into control or one of three 12-hr mechanical ventilation groups that were treated with/without a selective pharmacological protease inhibitor: 1) control, 2) mechanical ventilation, 3) mechanical ventilation with a selective caspase-3 inhibitor, and 4) mechanical ventilation with a selective calpain inhibitor. MEASUREMENTS AND MAIN RESULTS Compared to control, mechanical ventilation resulted in calpain and caspase-3 activation in the diaphragm accompanied by atrophy of type I, type IIa, and type IIx/IIb fibers. Independent inhibition of either calpain or caspase-3 prevented this mechanical ventilation-induced atrophy. Pharmacological inhibition of calpain prevented mechanical ventilation-induced activation of diaphragmatic caspase-3 and inhibition of caspase-3 prevented activation of diaphragmatic calpain. Furthermore, calpain inhibition also prevented the activation of caspase-9 and caspase-12, along with the cleavage of Bid to tBid, all upstream signals for caspase-3 activation. Lastly, caspase-3 inhibition prevented the mechanical ventilation-induced degradation of the endogenous calpain inhibitor, calpastatin. CONCLUSIONS Collectively, these results indicate that mechanical ventilation-induced diaphragmatic atrophy is dependent on the activation of both calpain and caspase-3. Importantly, these findings provide the first experimental evidence in diaphragm muscle that calpain inhibition prevents the activation of caspase-3 and vice versa and caspase-3 inhibition prevents the activation of calpain. These findings support our hypothesis that a regulatory calpain/caspase-3 cross-talk exists whereby calpain can promote caspase-3 activation and active caspase-3 can enhance calpain activity in diaphragm muscle during prolonged mechanical ventilation.
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Mitochondria-targeted antioxidants protect against mechanical ventilation-induced diaphragm weakness. Crit Care Med 2011; 39:1749-59. [PMID: 21460706 DOI: 10.1097/ccm.0b013e3182190b62] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Mechanical ventilation is a life-saving intervention used to provide adequate pulmonary ventilation in patients suffering from respiratory failure. However, prolonged mechanical ventilation is associated with significant diaphragmatic weakness resulting from both myofiber atrophy and contractile dysfunction. Although several signaling pathways contribute to diaphragm weakness during mechanical ventilation, it is established that oxidative stress is required for diaphragmatic weakness to occur. Therefore, identifying the site(s) of mechanical ventilation- induced reactive oxygen species production in the diaphragm is important. OBJECTIVE These experiments tested the hypothesis that elevated mitochondrial reactive oxygen species emission is required for mechanical ventilation-induced oxidative stress, atrophy, and contractile dysfunction in the diaphragm. DESIGN Cause and effect was determined by preventing mechanical ventilation-induced mitochondrial reactive oxygen species emission in the diaphragm of rats using a novel mitochondria-targeted antioxidant (SS-31). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Compared to mechanically ventilated animals treated with saline, animals treated with SS-31 were protected against mechanical ventilation-induced mitochondrial dysfunction, oxidative stress, and protease activation in the diaphragm. Importantly, treatment of animals with the mitochondrial antioxidant also protected the diaphragm against mechanical ventilation-induced myofiber atrophy and contractile dysfunction. CONCLUSIONS These results reveal that prevention of mechanical ventilation-induced increases in diaphragmatic mitochondrial reactive oxygen species emission protects the diaphragm from mechanical ventilation-induced diaphragmatic weakness. This important new finding indicates that mitochondria are a primary source of reactive oxygen species production in the diaphragm during prolonged mechanical ventilation. These results could lead to the development of a therapeutic intervention to impede mechanical ventilation-induced diaphragmatic weakness.
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Smuder AJ, Kavazis AN, Hudson MB, Nelson WB, Powers SK. Oxidation enhances myofibrillar protein degradation via calpain and caspase-3. Free Radic Biol Med 2010; 49:1152-60. [PMID: 20600829 PMCID: PMC2930052 DOI: 10.1016/j.freeradbiomed.2010.06.025] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 05/10/2010] [Accepted: 06/21/2010] [Indexed: 01/12/2023]
Abstract
Oxidative stress has been linked to accelerated rates of proteolysis and muscle fiber atrophy during periods of prolonged skeletal muscle inactivity. However, the mechanism(s) that links oxidative stress to muscle protein degradation remains unclear. A potential connection between oxidants and accelerated proteolysis in muscle fibers is that oxidative modification of myofibrillar proteins may enhance their susceptibility to proteolytic processing. In this regard, it is established that protein oxidation promotes protein recognition and degradation by the 20S proteasome. However, it is unknown whether oxidation of myofibrillar proteins increases their recognition and degradation by calpains and/or caspase-3. Therefore, we tested the hypothesis that oxidative modification of myofibrillar proteins increases their susceptibility to degradation by both calpains and caspase-3. To test this postulate, myofibrillar proteins were isolated from rat skeletal muscle and exposed to in vitro oxidation to produce varying levels of protein modification. Modified proteins were then independently incubated with active calpain I, calpain II, or caspase-3 and the rates of protein degradation were assessed via peptide mapping. Our results reveal that increased protein oxidation results in a stepwise escalation in the degradation of myofibrillar proteins by calpain I, calpain II, and caspase-3. These findings provide a mechanistic link connecting oxidative stress with accelerated myofibrillar proteolysis during disuse muscle atrophy.
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Affiliation(s)
- Ashley J Smuder
- Center for Exercise Science, Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32611, USA
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Prigol M, Luchese C, Nogueira CW. Antioxidant effect of diphenyl diselenide on oxidative stress caused by acute physical exercise in skeletal muscle and lungs of mice. Cell Biochem Funct 2009; 27:216-22. [DOI: 10.1002/cbf.1559] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Kavazis AN, Talbert EE, Smuder AJ, Hudson MB, Nelson WB, Powers SK. Mechanical ventilation induces diaphragmatic mitochondrial dysfunction and increased oxidant production. Free Radic Biol Med 2009; 46:842-50. [PMID: 19185055 PMCID: PMC2906125 DOI: 10.1016/j.freeradbiomed.2009.01.002] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 01/07/2009] [Accepted: 01/08/2009] [Indexed: 12/16/2022]
Abstract
Mechanical ventilation (MV) is a life-saving intervention used in patients with acute respiratory failure. Unfortunately, prolonged MV results in diaphragmatic weakness, which is an important contributor to the failure to wean patients from MV. Our laboratory has previously shown that reactive oxygen species (ROS) play a critical role in mediating diaphragmatic weakness after MV. However, the pathways responsible for MV-induced diaphragmatic ROS production remain unknown. These experiments tested the hypothesis that prolonged MV results in an increase in mitochondrial ROS release, mitochondrial oxidative damage, and mitochondrial dysfunction. To test this hypothesis, adult (3-4 months of age) female Sprague-Dawley rats were assigned to either a control or a 12-h MV group. After treatment, diaphragms were removed and mitochondria were isolated for subsequent respiratory and biochemical measurements. Compared to control, prolonged MV resulted in a lower respiratory control ratio in diaphragmatic mitochondria. Furthermore, diaphragmatic mitochondria from MV animals released higher rates of ROS in both State 3 and State 4 respiration. Prolonged MV was also associated with diaphragmatic mitochondrial oxidative damage as indicated by increased lipid peroxidation and protein oxidation. Finally, our data also reveal that the activities of the electron transport chain complexes II, III, and IV are depressed in mitochondria isolated from diaphragms of MV animals. In conclusion, these results are consistent with the concept that diaphragmatic inactivity promotes an increase in mitochondrial ROS emission, mitochondrial oxidative damage, and mitochondrial respiratory dysfunction.
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Affiliation(s)
- Andreas N Kavazis
- Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32611, USA.
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16
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Whidden MA, McClung JM, Falk DJ, Hudson MB, Smuder AJ, Nelson WB, Powers SK. Xanthine oxidase contributes to mechanical ventilation-induced diaphragmatic oxidative stress and contractile dysfunction. J Appl Physiol (1985) 2008; 106:385-94. [PMID: 18974366 DOI: 10.1152/japplphysiol.91106.2008] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Respiratory muscle weakness resulting from both diaphragmatic contractile dysfunction and atrophy has been hypothesized to contribute to the weaning difficulties associated with prolonged mechanical ventilation (MV). While it is clear that oxidative injury contributes to MV-induced diaphragmatic weakness, the source(s) of oxidants in the diaphragm during MV remain unknown. These experiments tested the hypothesis that xanthine oxidase (XO) contributes to MV-induced oxidant production in the rat diaphragm and that oxypurinol, a XO inhibitor, would attenuate MV-induced diaphragmatic oxidative stress, contractile dysfunction, and atrophy. Adult female Sprague-Dawley rats were randomly assigned to one of six experimental groups: 1) control, 2) control with oxypurinol, 3) 12 h of MV, 4) 12 h of MV with oxypurinol, 5) 18 h of MV, or 6) 18 h of MV with oxypurinol. XO activity was significantly elevated in the diaphragm after MV, and oxypurinol administration inhibited this activity and provided protection against MV-induced oxidative stress and contractile dysfunction. Specifically, oxypurinol treatment partially attenuated both protein oxidation and lipid peroxidation in the diaphragm during MV. Further, XO inhibition retarded MV-induced diaphragmatic contractile dysfunction at stimulation frequencies >60 Hz. Collectively, these results suggest that oxidant production by XO contributes to MV-induced oxidative injury and contractile dysfunction in the diaphragm. Nonetheless, the failure of XO inhibition to completely prevent MV-induced diaphragmatic oxidative damage suggests that other sources of oxidant production are active in the diaphragm during prolonged MV.
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Affiliation(s)
- Melissa A Whidden
- Dept. of Applied Physiology and Kinesiology, Univ. of Florida,Gainesville, FL 32611, USA
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17
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Lin H, Tong TK, Huang C, Nie J, Lu K, Quach B. Specific inspiratory muscle warm-up enhances badminton footwork performance. Appl Physiol Nutr Metab 2008; 32:1082-8. [PMID: 18059581 DOI: 10.1139/h07-077] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered in a subsequent incremental badminton-footwork test (FWmax) were examined. Ten male badminton players were recruited to perform identical tests in three different trials in a random order. The control trial did not involve an IM warm-up, whereas the placebo and experimental trials did involve an IM warm-up consisting of two sets of 30-breath manoeuvres with an inspiratory pressure-threshold load equivalent to 15% (PLA) and 40% (IMW) maximum inspiratory mouth pressure, respectively. In the IMW trial, IM function was improved with 7.8%+/-4.0% and 6.9%+/-3.5% increases from control found in maximal inspiratory pressure at zero flow (P0) and maximal rate of P0 development (MRPD), respectively (p<0.05). FWmax was enhanced 6.8%+/-3.7%, whereas the slope of the linear relationship of the increase in the rating of perceived breathlessness for every minute (RPB/min) was reduced (p<0.05). Reduction in blood lactate ([La-]b) accumulation was observed when the test duration was identical to that of the control trial (P<0.05). In the PLA trial, no parameter was changed from control. For the changes (Delta) in parameters in IMW (n=10), negative correlations were found between DeltaP0 and DeltaRPB/min (r2=0.58), DeltaMRPD and DeltaRPB/min (r2=0.48), DeltaRPB/min, and DeltaFWmax (r2=0.55), but not between Delta[La-]b accumulation and DeltaFWmax. Such findings suggest that the IM-specific warm-up improved footwork performance in the subsequent maximum incremental badminton-footwork test. The improved footwork was partly attributable to the reduced breathless sensation resulting from the enhanced IM function, whereas the contribution of the concomitant reduction in [La-]b accumulation was relatively minor.
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Affiliation(s)
- Hua Lin
- Physical Education Department, Liaoning Normal University, Huanghe Road 850, Dalian, Liaoning, China
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18
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Falk DJ, Deruisseau KC, Van Gammeren DL, Deering MA, Kavazis AN, Powers SK. Mechanical ventilation promotes redox status alterations in the diaphragm. J Appl Physiol (1985) 2006; 101:1017-24. [PMID: 16675618 DOI: 10.1152/japplphysiol.00104.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Oxidative stress is an important mediator of diaphragm muscle atrophy and contractile dysfunction during prolonged periods of controlled mechanical ventilation (MV). To date, specific details related to the impact of MV on diaphragmatic redox status remain unknown. To fill this void, we tested the hypothesis that MV-induced diaphragmatic oxidative stress is the consequence of both an elevation in intracellular oxidant production in conjunction with a decrease in the antioxidant buffering capacity. Adult rats were assigned to one of two experimental groups: 1) control or 2) 12 h of MV. Compared with controls, diaphragms from MV animals demonstrated increased oxidant production, diminished total antioxidant capacity, and decreased glutathione levels. Heme oxygenase-1 (HO-1) mRNA and protein levels increased (23.0- and 5.1-fold, respectively) following MV. Thioredoxin reductase-1 and manganese superoxide dismutase mRNA levels were also increased in the diaphragm following MV (2.4- and 1.6-fold, respectively), although no change was detected in the levels of either protein. Furthermore, copper-zinc superoxide dismutase and glutathione peroxidase mRNA were not altered following MV, although protein content decreased -1.3- and -1.7-fold, respectively. We conclude that MV promotes increased oxidant production and impairment of key antioxidant defenses in the diaphragm; collectively, these changes contribute to the MV-induced oxidative stress in this key inspiratory muscle.
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Affiliation(s)
- D J Falk
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, 32611, USA
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19
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Van Gammeren D, Falk DJ, DeRuisseau KC, Sellman JE, Decramer M, Powers SK. Reloading the Diaphragm Following Mechanical Ventilation Does Not Promote Injury. Chest 2005; 127:2204-10. [PMID: 15947338 DOI: 10.1378/chest.127.6.2204] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVE Mechanical ventilation (MV) is used clinically to treat patients who are incapable of maintaining adequate alveolar ventilation. Prolonged MV is associated with diaphragmatic atrophy and a decrement in maximal specific force production (P(O)). Collectively, these alterations may predispose the diaphragm to injury on the return to spontaneous breathing (ie, reloading). Therefore, these experiments tested the hypothesis that reloading the diaphragm following MV exacerbates MV-induced diaphragmatic contractile dysfunction, while causing muscle fiber membrane damage and inflammation. METHODS To test this postulate, Sprague-Dawley rats were randomly assigned to the following groups: (1) control; (2) 24 h of controlled MV; and (3) 24 h of controlled MV followed by 2 h of anesthetized spontaneous breathing. Controls were anesthetized in the short term but were not exposed to MV, whereas MV animals were anesthetized, tracheostomized, and ventilated. Reloaded animals remained under anesthesia, but were removed from MV and returned to spontaneous breathing for 2 h. RESULTS Compared to the situation with control animals, MV resulted in a 26% decrement in diaphragmatic specific P(O) without muscle fiber membrane damage, as measured by an increase in membrane permeability (using the procion orange technique). Further, there were no increases in neutrophil or macrophage influx. Two hours of reloading did not exacerbate MV-induced diaphragmatic contractile dysfunction or cause fiber membrane damage, but increased neutrophil infiltration, myeloperoxidase activity, and muscle edema. CONCLUSION We conclude that the return to spontaneous breathing following 24 h of controlled MV does not exacerbate MV-induced diaphragm contractile dysfunction or result in fiber membrane damage, but increases neutrophil infiltration.
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Affiliation(s)
- Darin Van Gammeren
- Department of Applied Psychology, Center for Exercise Science, University of Florida, Room 25 FLG, Gainesville, FL 32611, USA
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20
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Washington TA, Reecy JM, Thompson RW, Lowe LL, McClung JM, Carson JA. Lactate dehydrogenase expression at the onset of altered loading in rat soleus muscle. J Appl Physiol (1985) 2005; 97:1424-30. [PMID: 15358753 DOI: 10.1152/japplphysiol.00222.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Both functional overload and hindlimb disuse induce significant energy-dependent remodeling of skeletal muscle. Lactate dehydrogenase (LDH), an important enzyme involved in anaerobic glycolysis, catalyzes the interconversion of lactate and pyruvate critical for meeting rapid high-energy demands. The purpose of this study was to determine rat soleus LDH-A and -B isoform expression, mRNA abundance, and enzymatic activity at the onset of increased or decreased loading in the rat soleus muscle. The soleus muscles from male Sprague-Dawley rats were functionally overloaded for up to 3 days by a modified synergist ablation or subjected to disuse by hindlimb suspension for 3 days. LDH mRNA concentration was determined by Northern blotting, LDH protein isoenzyme composition was determined by zymogram analysis, and LDH enzymatic activity was determined spectrophotometrically. LDH-A mRNA abundance increased by 372%, and LDH-B mRNA abundance decreased by 43 and 31% after 24 h and 3 days of functional overload, respectively, compared with that in control rats. LDH protein expression demonstrated a shift by decreasing LDH-B isoforms and increasing LDH-A isoforms. LDH-B activity decreased 80% after 3 days of functional overload. Additionally, LDH-A activity increased by 234% following 3 days of hindlimb suspension. However, neither LDH-A or LDH-B mRNA abundance was affected following 3 days of hindlimb suspension. In summary, the onset of altered loading induced a differential expression of LDH-A and -B in the rat soleus muscle, favoring rapid energy production. Long-term altered loading is associated with myofiber conversion; however, the rapid changes in LDH at the onset of altered loading may be involved in other physiological processes.
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Affiliation(s)
- Tyrone A Washington
- Integrative Muscle Biology Laboratory, Exercise Science Department, Norman J. Arnold School of Public Health, University of South Carolina 29208, USA
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21
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DeRuisseau KC, Kavazis AN, Deering MA, Falk DJ, Van Gammeren D, Yimlamai T, Ordway GA, Powers SK. Mechanical ventilation induces alterations of the ubiquitin-proteasome pathway in the diaphragm. J Appl Physiol (1985) 2005; 98:1314-21. [PMID: 15557010 DOI: 10.1152/japplphysiol.00993.2004] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prolonged mechanical ventilation (MV) results in diaphragmatic atrophy due, in part, to an increase in proteolysis. These experiments tested the hypothesis that MV-induced diaphragmatic proteolysis is accompanied by increased expression of key components of the ubiquitin-proteasome pathway (UPP). To test this postulate, we investigated the effect of prolonged MV on UPP components and determined the trypsin-like and peptidylglutamyl peptide hydrolyzing activities of the 20S proteasome. Adult Sprague-Dawley rats were assigned to either control or 12-h MV groups ( n = 7/group). MV animals were anesthetized, tracheostomized, and ventilated with room air for 12 h. Animals in the control group were acutely anesthetized but not exposed to MV. Compared with controls, MV animals demonstrated increased diaphragmatic mRNA levels of two ubiquitin ligases, muscle atrophy F-box (+8.3-fold) and muscle ring finger 1 (+19.0-fold). However, MV did not alter mRNA levels of 14-kDa ubiquitin-conjugating enzyme, polyubiquitin, proteasome-activating complex PA28, or 20S α-subunit 7. Protein levels of 14-kDa ubiquitin-conjugating enzyme and proteasome-activating complex PA28 were not altered following MV, but 20S α-subunit 7 levels declined (−17.7%). MV increased diaphragmatic trypsin-like activity (+31%) but did not alter peptidylglutamyl peptide hydrolyzing activity. Finally, compared with controls, MV increased ubiquitin-protein conjugates in both the myofibrillar (+24.9%) and cytosolic (+54.7%) fractions of the diaphragm. These results are consistent with the hypothesis that prolonged MV increases diaphragmatic levels of key components within the UPP and that increases in 20S proteasome activity contribute to MV-induced diaphragmatic proteolysis and atrophy.
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Affiliation(s)
- Keith C DeRuisseau
- Center for Exercise Science, Univ. of Florida, Rm 25 FLG, Gainesville, FL 32611, USA
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22
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Shanely RA, Van Gammeren D, Deruisseau KC, Zergeroglu AM, McKenzie MJ, Yarasheski KE, Powers SK. Mechanical ventilation depresses protein synthesis in the rat diaphragm. Am J Respir Crit Care Med 2004; 170:994-9. [PMID: 15297271 DOI: 10.1164/rccm.200304-575oc] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Prolonged mechanical ventilation results in diaphragmatic atrophy and contractile dysfunction in animals. We hypothesized that mechanical ventilation-induced diaphragmatic atrophy is associated with decreased synthesis of both mixed muscle protein and myosin heavy chain protein in the diaphragm. To test this postulate, adult rats were mechanically ventilated for 6, 12, or 18 hours and diaphragmatic protein synthesis was measured in vivo. Six hours of mechanical ventilation resulted in a 30% decrease (p < 0.05) in the rate of mixed muscle protein synthesis and a 65% decrease (p < 0.05) in the rate of myosin heavy chain protein synthesis; this depression in diaphragmatic protein synthesis persisted throughout 18 hours of mechanical ventilation. Real-time polymerase chain reaction analyses revealed that mechanical ventilation, in comparison with time-matched controls, did not alter diaphragmatic levels of Type I and IIx myosin heavy chain messenger ribonucleic acid levels in the diaphragm. These data support the hypothesis that mechanical ventilation results in a decrease in both mixed muscle protein and myosin heavy chain protein synthesis in the diaphragm. Further, the decline in myosin heavy chain protein synthesis does not appear to be associated with a decrease in myosin heavy chain messenger ribonucleic acid.
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Affiliation(s)
- R Andrew Shanely
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville 32611, USA
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23
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Hansen G, Martinuk KJB, Bell GJ, MacLean IM, Martin TP, Putman CT. Effects of spaceflight on myosin heavy-chain content, fibre morphology and succinate dehydrogenase activity in rat diaphragm. Pflugers Arch 2004; 448:239-47. [PMID: 14985980 DOI: 10.1007/s00424-003-1230-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Accepted: 11/26/2003] [Indexed: 10/26/2022]
Abstract
The present study examined the effect of 14 days of exposure to microgravity during the Spacelab Life Sciences-2 (SLS-2) space shuttle mission on the myosin heavy-chain (MHC) content, fibre size and type distributions and metabolic properties of rat diaphragm. Five adult male Sprague-Dawley rats were exposed to 14 days of microgravity (SF, spaceflight) and compared to five ground-based controls (C). Immunohistochemical analyses using isoform-specific anti-MHC monoclonal antibodies revealed that 14 days of SF did not alter the proportions of type-I, -IIA, -IID/X or -IIB fibres within the crural, sternal or lateral costal regions of the diaphragm; the electrophoretically quantified MHC-isoform contents also remained unchanged. In contrast, the medial gastrocnemius (MG) and tibialis anterior (TA) muscles displayed slow-to-fast fibre type transitions: within the MG the proportion of type-IID/X fibres was reduced by 59% ( P<0.04) and corresponded to a 51% increase ( P<0.03) in type-IIB fibres. Within the TA, the sum of type-IID/X+IIB fibres was elevated by 24% ( P<0.02) at the expense of the slower type-IIA fibres, which decreased by 33% ( P<0.04). Electrophoretic analyses yielded qualitatively similar patterns of transformation. SF did not induce atrophic changes within the diaphragm, MG or TA. Succinate dehydrogenase activity remained unchanged in the crural diaphragm ( P>0.96) but was 34% lower ( P<0.0001) in the TA. We conclude that 14 days of SF did not alter structural or metabolic factors that are known to underlie functional properties of the diaphragm. The findings of the present study show that 14 days of SF does not induce deleterious adaptive changes in the rat diaphragm that occur in hindlimb muscles.
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MESH Headings
- Animals
- Atrophy
- Cell Size
- Diaphragm/metabolism
- Diaphragm/physiology
- Diaphragm/ultrastructure
- Electrophoresis, Polyacrylamide Gel
- Hindlimb/physiology
- Immunohistochemistry
- Male
- Muscle Fibers, Fast-Twitch/physiology
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Skeletal/physiology
- Muscle Fibers, Skeletal/ultrastructure
- Muscle Fibers, Slow-Twitch/physiology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- Muscle, Skeletal/ultrastructure
- Myosin Heavy Chains/metabolism
- Phenotype
- Rats
- Rats, Sprague-Dawley
- Space Flight
- Succinate Dehydrogenase/metabolism
- Weightlessness/adverse effects
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Affiliation(s)
- Gregory Hansen
- Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, T6G 2H9, Edmonton, Alberta, Canada
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24
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Zergeroglu MA, McKenzie MJ, Shanely RA, Van Gammeren D, DeRuisseau KC, Powers SK. Mechanical ventilation-induced oxidative stress in the diaphragm. J Appl Physiol (1985) 2003; 95:1116-24. [PMID: 12777408 DOI: 10.1152/japplphysiol.00824.2002] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prolonged mechanical ventilation (MV) results in oxidative damage in the diaphragm; however, it is unclear whether this MV-induced oxidative injury occurs rapidly or develops slowly over time. Furthermore, it is unknown whether both soluble (cytosolic) and insoluble (myofibrillar) proteins are equally susceptible to oxidation during MV. These experiments tested two hypotheses: 1). MV-induced oxidative injury in the diaphragm occurs within the first 6 h after the initiation of MV; and 2). MV is associated with oxidative modification of both soluble and insoluble proteins. Adult Sprague-Dawley rats were randomly divided into one of seven experimental groups: 1) control (n = 8); 2) 3-h MV (n = 8); 3). 6-h MV (n = 6); 4). 18-h MV (n = 8); 5). 3-h anesthesia-spontaneous breathing (n = 8); 6). 6-h anesthesia-spontaneous breathing (n = 6); and 7). 18-h anesthesia-spontaneous breathing (n = 8). Markers of oxidative injury in the diaphragm included the measurement of reactive (protein) carbonyl derivatives (RCD) and total lipid hydroperoxides. Three hours of MV did not result in oxidative injury in the diaphragm. In contrast, both 6 and 18 h of MV promoted oxidative injury in the diaphragm, as indicated by increases in both protein RCD and lipid hydroperoxides. Electrophoretic separation of soluble and insoluble proteins indicated that the MV-induced accumulation of RCD was limited to insoluble proteins with molecular masses of approximately 200, 120, 80, and 40 kDa. We conclude that MV results in a rapid onset of oxidative injury in the diaphragm and that insoluble proteins are primary targets of MV-induced protein oxidation.
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Affiliation(s)
- Murat A Zergeroglu
- Department of Execise and Sport Sciences, Center for Exercise Science, University of Florida, Gainesville, FL 32601, USA
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25
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Shanely RA, Coombes JS, Zergeroglu AM, Webb AI, Powers SK. Short-duration mechanical ventilation enhances diaphragmatic fatigue resistance but impairs force production. Chest 2003; 123:195-201. [PMID: 12527622 DOI: 10.1378/chest.123.1.195] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVE s: Mechanical ventilation (MV) is a life-support measure for patients who cannot maintain adequate alveolar ventilation. Following prolonged MV, difficulty in weaning patients from the ventilator can occur, and it has been postulated that difficult weaning is linked to respiratory muscle dysfunction. We tested the hypothesis that 18 h of controlled MV will diminish diaphragmatic maximal tetanic specific tension (force per cross-sectional area of muscle) without impairing diaphragmatic fatigue resistance. DESIGN To test this postulate, adult Sprague-Dawley rats were randomly classified into one of two experimental groups: (1) control group (n = 8), and (2) 18-h MV group (n = 6). MV-treated animals were anesthetized, tracheostomized, and received room air ventilation. Animals in the control group were acutely anesthetized but did not receive MV. Muscle strips from the mid-costal diaphragm were removed from both experimental groups, and contractile properties were studied in vitro to determine the effects of MV on diaphragmatic endurance and maximal force production. Diaphragmatic endurance was investigated by measuring tension development during repeated contractions throughout a 30-min fatigue protocol. RESULTS MV resulted in a reduction (p < 0.05) in diaphragmatic maximal specific tension (control group, 26.8 +/- 0.2 Newtons/cm(2) vs MV group, 21.3 +/- 0.6 Newtons/cm(2)). Compared to the control group, diaphragms from MV-treated animals maintained higher (p < 0.05) percentages of the initial force production throughout the fatigue protocol. The observed improvement in fatigue resistance was associated with an increase in diaphragmatic oxidative and antioxidant capacity as evidenced by increases (p < 0.05) in both citrate synthase and superoxide dismutase activities. However, by comparison to the control group, diaphragms from MV-treated animals generated less (p < 0.05) absolute specific force throughout the fatigue protocol. CONCLUSIONS These data indicate that 18 h of MV enhances diaphragmatic fatigue resistance but impairs diaphragmatic specific tension.
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Affiliation(s)
- R Andrew Shanely
- Department of Exercise and Sport Sciences, University of Florida, Gainesville, FL 32601, USA
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26
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Powers SK, Shanely RA, Coombes JS, Koesterer TJ, McKenzie M, Van Gammeren D, Cicale M, Dodd SL. Mechanical ventilation results in progressive contractile dysfunction in the diaphragm. J Appl Physiol (1985) 2002; 92:1851-8. [PMID: 11960933 DOI: 10.1152/japplphysiol.00881.2001] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
These experiments tested the hypothesis that a relatively short duration of controlled mechanical ventilation (MV) will impair diaphragmatic maximal specific force generation (specific P(o)) and that this force deficit will be exacerbated with increased time on the ventilator. To test this postulate, adult Sprague-Dawley rats were randomly divided into one of six experimental groups: 1) control (n = 12); 2) 12 h of MV (n = 4); 3) 18 h of MV (n = 4); 4) 18 h of anesthesia and spontaneous breathing (n = 4); 5) 24 h of MV (n = 7); and 6) 24 h of anesthesia and spontaneous breathing (n = 4). MV animals were anesthetized, tracheostomized, and ventilated with room air. Animals in the control group were acutely anesthetized but were not exposed to MV. Animals in two spontaneous breathing groups were anesthetized and breathed spontaneously for either 18 or 24 h. No differences (P > 0.05) existed in diaphragmatic specific P(o) between control and the two spontaneous breathing groups. In contrast, compared with control, all durations of MV resulted in a reduction (P < 0.05) in diaphragmatic specific tension at stimulation frequencies ranging from 15 to 160 Hz. Furthermore, the MV-induced decrease in diaphragmatic specific P(o) was time dependent, with specific P(o) being approximately 18 and approximately 46% lower (P < 0.05) in animals mechanically ventilated for 12 and 24 h, respectively. These data support the hypothesis that relatively short-term MV impairs diaphragmatic contractile function and that the magnitude of MV-induced force deficit increases with time on the ventilator.
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Affiliation(s)
- Scott K Powers
- Department of Exercise and Sport Sciences, University of Florida, Gainesville 32611, USA.
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27
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Bortolotto SK, Cellini M, Stephenson DG, Stephenson GM. MHC isoform composition and Ca(2+)- or Sr(2+)-activation properties of rat skeletal muscle fibers. Am J Physiol Cell Physiol 2000; 279:C1564-77. [PMID: 11029304 DOI: 10.1152/ajpcell.2000.279.5.c1564] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chemically skinned single fibers from adult rat skeletal muscles were used to test the hypothesis that, in mammalian muscle fibers, myosin heavy chain (MHC) isoform expression and Ca(2+)- or Sr(2+)-activation characteristics are only partly correlated. The fibers were first activated in Ca(2+)- or Sr(2+)-buffered solutions under near-physiological conditions, and then their MHC isoform composition was determined electrophoretically. Fibers expressing only the MHC I isoform could be appropriately identified on the basis of either the Ca(2+)- or Sr(2+)-activation characteristics or the MHC isoform composition. Fibers expressing one or a combination of fast MHC isoforms displayed no significant differences in their Ca(2+)- or Sr(2+)-activation properties; therefore, their MHC isoform composition could not be predicted from their Ca(2+)- or Sr(2+)-activation characteristics. A large proportion of fibers expressing both fast- and slow-twitch MHC isoforms displayed Ca(2+)- or Sr(2+)-activation properties that were not consistent with their MHC isoform composition; thus both fiber-typing methods were needed to fully characterize such fibers. These data show that, in rat skeletal muscles, the extent of correlation between MHC isoform expression and Ca(2+)- or Sr(2+)-activation characteristics is fiber-type dependent.
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Affiliation(s)
- S K Bortolotto
- School of Life Sciences and Technology, Victoria University of Technology, Melbourne, Victoria 8001, Australia
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28
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Caillaud C, Py G, Eydoux N, Legros P, Prefaut C, Mercier J. Antioxidants and mitochondrial respiration in lung, diaphragm, and locomotor muscles: effect of exercise. Free Radic Biol Med 1999; 26:1292-9. [PMID: 10381202 DOI: 10.1016/s0891-5849(98)00342-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous studies have shown that exhaustive exercise may increase reactive oxygen species (ROS) generation in oxidative muscles that may in turn impair mitochondrial respiration. Locomotor muscles have been extensively examined, but there is few report about diaphragm or lung. The later is a privileged site for oxygen transit. To compare the antioxidant defense system and mitochondrial function in lung, diaphragm and locomotor muscles after exercise, 24 young adult male rats were randomly assigned to a control (C) or exercise (E) group. E group rats performed an exhaustive running test on a motorized treadmill at 80-85% VO2max Mean exercise duration was 66+/-2.7 min. Lung, costal diaphragm, mixed gastrocnemius, and oxidative muscles (red gastrocnemius and soleus: RG/SOL homogenate) were sampled. Mitochondrial respiration was assessed in tissue homogenates by respiratory control index (RCI: rate of uncoupled respiration/rate of basal respiration) measurement. Lipid peroxidation was evaluated by malondialdehyde concentration (MDA) and we determined the activity of two antioxidant enzymes: superoxide dismutase (SOD) and glutathione peroxidase (GPX). We found elevated basal (C group data) SOD and GPX activities in both lung and diaphragm compared to locomotor muscles (p<.001). Exercise led to a rise in GPX activity in red locomotor muscles homogenate (GR/SOL; C = 10.3+/-0.29 and E = 14.4+/-1.51 micromol x min(-1) x gww(-1); p<.05), whereas there was no significant change in lung and diaphragm. MDA concentration and mitochondrial RCI values were not significantly changed after exercise. We conclude that lung and diaphragm had higher antioxidant protection than locomotor muscles. The exercise test did not lead to significant oxidative stress or alteration in mitochondrial respiration, suggesting that antioxidant function was adequate in both lung and diaphragm in the experimental condition.
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Affiliation(s)
- C Caillaud
- Laboratoire d'Analyse de la Performance Motrice Humaine, Faculté des Sciences du Sport; Poitiers, France.
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