期刊
AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY
卷 303, 期 12, 页码 L1070-L1078出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajplung.00135.2012
关键词
single fiber; cross bridge cycling kinetics; Ca2+ sensitivity; myosin heavy chain
资金
- VENI grant from the Netherlands Foundation for Scientific Research (NWO)
Manders E, de Man FS, Handoko ML, Westerhof N, van Hees HW, Stienen GJ, Vonk-Noordegraaf A, Ottenheijm CA. Diaphragm weakness in pulmonary arterial hypertension: role of sarcomeric dysfunction. Am J Physiol Lung Cell Mol Physiol 303: L1070-L1078, 2012. First published September 7, 2012; doi: 10.1152/ajplung.00135.2012.-We previously demonstrated that diaphragm muscle weakness is present in experimental pulmonary arterial hypertension (PH). However, the nature of this diaphragm weakness is still unknown. Therefore, the aim of this study was to investigate whether changes at the sarcomeric level contribute to diaphragm weakness in PH. For this purpose, in control rats and rats with monocrotaline-induced PH, contractile performance and myosin heavy chain content of demembranated single diaphragm fibers were determined. We observed a reduced maximal tension of 20% (P < 0.05), whereas tension cost was preserved in type 2X and 2B diaphragm fibers in PH compared with control. The reduced maximal tension was associated with a reduction of force generated per half-sarcomeric myosin heavy chain content. Additionally, reduced Ca2+ sensitivity of force generation was found in type 2X fibers compared with control, which could exacerbate diaphragm muscle weakness at submaximal activation. No changes in maximal tension and Ca2+ sensitivity of force generation were observed in fibers from the nonrespiratory extensor digitorum longus muscle. Together, these findings indicate that diaphragm weakness in PH is at least partly caused by sarcomeric dysfunction, which appears to be specific for the diaphragm.
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