Authors

Dong Kwan Kim, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA, Present address: Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Jianliang Zhu, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
Benjamin W Kozyak, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
James M Burkman, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
Neal A Rubinstein, Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
Edward B Lankford, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USAFollow
Hansell H Stedman, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA, Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA, Department of Surgery, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
Taitan Nguyen, Department of Medicine, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
Sanford Levine, Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA, Department of Medicine, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
Joseph B Shrager, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA, Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA, Department of Surgery, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USAFollow

Document Type

Article

Publication Date

1-1-2003

Comments

This article has been peer reviewed and is published in BMC Respiratory Research Volume 4, 17 February 2003, 10p. The published version is available at DOI: 10.1186/rr196. Copyright © BioMed Central Ltd.

Abstract

BACKGROUND: Several physiological adaptations occur in the respiratory muscles in rodent models of elastase-induced emphysema. Although the contractile properties of the diaphragm are altered in a way that suggests expression of slower isoforms of myosin heavy chain (MHC), it has been difficult to demonstrate a shift in MHCs in an animal model that corresponds to the shift toward slower MHCs seen in human emphysema. METHODS: We sought to identify MHC and corresponding physiological changes in the diaphragms of rats with elastase-induced emphysema. Nine rats with emphysema and 11 control rats were studied 10 months after instillation with elastase. MHC isoform composition was determined by both reverse transcriptase polymerase chain reaction (RT-PCR) and immunocytochemistry by using specific probes able to identify all known adult isoforms. Physiological adaptation was studied on diaphragm strips stimulated in vitro. RESULTS: In addition to confirming that emphysematous diaphragm has a decreased fatigability, we identified a significantly longer time-to-peak-tension (63.9 +/- 2.7 ms versus 53.9 +/- 2.4 ms). At both the RNA (RT-PCR) and protein (immunocytochemistry) levels, we found a significant decrease in the fastest, MHC isoform (IIb) in emphysema. CONCLUSION: This is the first demonstration of MHC shifts and corresponding physiological changes in the diaphragm in an animal model of emphysema. It is established that rodent emphysema, like human emphysema, does result in a physiologically significant shift toward slower diaphragmatic MHC isoforms. In the rat, this occurs at the faster end of the MHC spectrum than in humans.

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