Superoxide dismutase/catalase mimetic EUK-134 prevents diaphragm muscle weakness in monocrotalin-induced pulmonary hypertension - PubMed (original) (raw)

Superoxide dismutase/catalase mimetic EUK-134 prevents diaphragm muscle weakness in monocrotalin-induced pulmonary hypertension

Koichi Himori et al. PLoS One. 2017.

Abstract

Patients with pulmonary hypertension (PH) suffer from inspiratory insufficiency, which has been associated with intrinsic contractile dysfunction in diaphragm muscle. Here, we examined the role of redox stress in PH-induced diaphragm weakness by using the novel antioxidant, EUK-134. Male Wistar rats were randomly divided into control (CNT), CNT + EUK-134 (CNT + EUK), monocrotaline-induced PH (PH), and PH + EUK groups. PH was induced by a single intraperitoneal injection of monocrotaline (60 mg/kg body weight). EUK-134 (3 mg/kg body weight/day), a cell permeable mimetic of superoxide dismutase (SOD) and catalase, was daily intraperitoneally administered starting one day after induction of PH. After four weeks, diaphragm muscles were excised for mechanical and biochemical analyses. There was a decrease in specific tetanic force in diaphragm bundles from the PH group, which was accompanied by increases in: protein expression of NADPH oxidase 2/gp91phox, SOD2, and catalase; 3-nitrotyrosine content and aggregation of actin; glutathione oxidation. Treatment with EUK-134 prevented the force decrease and the actin modifications in PH diaphragm bundles. These data show that redox stress plays a pivotal role in PH-induced diaphragm weakness. Thus, antioxidant treatment can be a promising strategy for PH patients with inspiratory failure.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1

Fig 1. Specific force depression is accompanied by upregulation of redox enzymes in diaphragm from PH rat.

A: typical examples (100 Hz stimulation frequency, 600 ms train duration) of specific force in diaphragm fiber bundles from CNT and PH rats. B: Specific force at 100 Hz stimulation frequency. _C_-E: representative western blots illustrating the levels of NADPH oxidase (NOX2/gp91phox), neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS), superoxide dismutase 2 (SOD2), catalase (CAT), tumor necrosis factor (TNF)-α and high mobility group box 1 (HMGB1). Inducible NOS (iNOS) was not detected in either group. F: quantification of the levels of redox-related proteins and inflammatory mediators normalized to actin or troponin I (TnI) content. Data show mean ± SD for 5–8 rats in each group. *P < 0.05, **P < 0.01 vs. CNT.

Fig 2

Fig 2. Neither contractile proteins nor excitation-contraction coupling proteins are altered in PH diaphragm muscles.

A: Stain free images of myosin heavy chain (MyHC) and western blots of troponin (Tn) T. B: the expression levels of MyHC or TnT normalized to actin content. C: electrophoretically separated MyHC isoforms. D: percentage distribution of MyHC isoforms: I, slow myosin isoform; IIa, IId/x, and IIb, fast myosin isoforms. E: representative western blots of ryanodine receptor (RyR1), dihydropyridine receptor α2 subunit (DHPR), sarcoplasmic reticulum Ca2+-ATPase (SERCA) 1, and SERCA2. F: the expression levels of RyR1, DHPR, SERCA1, or SERCA2 normalized to actin content. Control (CNT), white bars; AIA, black bars. Data represent mean ± SD for 4–8 rats in each group.

Fig 3

Fig 3. Antioxidant treatment prevents contractile dysfunction in PH diaphragm muscles.

A: typical examples (120 Hz stimulation frequency, 600 ms train duration) of specific force in diaphragm fiber bundles from CNT and PH rats with or without EUK-134 (EUK) treatment. B: specific force-frequency relationship. Data show mean ± SD for 7–10 rats in each group. **P < 0.01 vs. CNT.

Fig 4

Fig 4. GSH: GSSG ratio is decreased in diaphragm muscles from PH rat.

The cytoplasm levels of GSH, GSSG, and the GSH: GSSG ratio in diaphragm muscles from CNT and PH rats with or without EUK-134 (EUK) treatment. Data show mean ± SD for 5–8 rats in each group. **P < 0.01 vs. CNT.

Fig 5

Fig 5. 3-nitrotyrosine content is increased in actin aggregates from PH diaphragm muscles.

A and B: representative western blots for 3-nitrotyrosine (3-NT) and actin in diaphragm muscles from CNT and PH rats with or without treatment with EUK-134 (EUK). C: intensities for the protein band at ~130 kDa (indicated by arrows) in 3-NT and actin were normalized to the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) content. Data show mean ± SD for 6 rats in each group. **P < 0.01 vs. CNT.

Similar articles

Cited by

References

    1. Sun XG, Hansen JE, Oudiz RJ, Wasserman K. Pulmonary function in primary pulmonary hypertension. J Am Coll Cardiol. 2003;41:1028–35. Epub 2003/03/26. - PubMed
    1. Meyer FJ, Lossnitzer D, Kristen AV, Schoene AM, Kubler W, Katus HA, et al. Respiratory muscle dysfunction in idiopathic pulmonary arterial hypertension. Eur Respir J. 2005;25:125–30. Epub 2005/01/11. 10.1183/09031936.04.00095804 - DOI - PubMed
    1. Kabitz HJ, Schwoerer A, Bremer HC, Sonntag F, Walterspacher S, Walker D, et al. Impairment of respiratory muscle function in pulmonary hypertension. Clin Sci (Lond). 2008;114:165–71. Epub 2007/09/04. - PubMed
    1. de Man FS, van Hees HW, Handoko ML, Niessen HW, Schalij I, Humbert M, et al. Diaphragm muscle fiber weakness in pulmonary hypertension. Am J Respir Crit Care Med. 2011;183:1411–8. 10.1164/rccm.201003-0354OC - DOI - PubMed
    1. Manders E, de Man FS, Handoko ML, Westerhof N, van Hees HW, Stienen GJ, et al. Diaphragm weakness in pulmonary arterial hypertension: role of sarcomeric dysfunction. Am J Physiol Lung Cell Mol Physiol. 2012;303:L1070–8. Epub 2012/09/11. 10.1152/ajplung.00135.2012 - DOI - PubMed

MeSH terms

Substances

Grants and funding

LinkOut - more resources