Long-term effects of clenbuterol on diaphragm morphology and contractile properties in emphysematous hamsters

• Published in: Journal of applied physiology (1985) 1998-07, Vol.85 (1), p.215-222
• Main Authors: Van Der Heijden, H. F. M, Dekhuijzen, P. N. R, Folgering, H, Ginsel, L. A, Van Herwaarden, C. L. A
• Format: Article
• Language: English
• Subjects: Adrenergic beta-Agonists - pharmacology; Animals; Biological and medical sciences; Body Weight - drug effects; Body Weight - physiology; Clenbuterol - pharmacology; Cricetinae; Diaphragm - growth & development; Diaphragm - pathology; Diaphragm - physiopathology; Drug therapy; Emphysema; Male; Medical sciences; Mesocricetus; Muscle Contraction - drug effects; Muscle Contraction - physiology; Muscle Development; Muscle Fibers, Skeletal - drug effects; Muscle Fibers, Skeletal - physiology; Organ Size - drug effects; Organ Size - physiology; Pharmacology. Drug treatments; Pulmonary Emphysema - pathology; Pulmonary Emphysema - physiopathology; Respiratory system; Rodents; Time Factors
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1998.85.1.215

1  Department of Pulmonary Diseases and 2  Department of Cell Biology and Histology, University Hospital Nijmegen, 6500 HB Nijmegen, The Netherlands The aim of the present study was to investigate the effect of chronic long-term clenbuterol treatment (1 mg/kg subcutaneously twice a day for 12 wk) on diaphragm morphology and function in emphysematous (EH) and normal hamsters (NH). Clenbuterol increased body weight, diaphragm weight, and skeletal muscle weight in both EH and NH to a similar extent. In the diaphragm, clenbuterol significantly increased myosin heavy chain type I, IIa, and IIx muscle fiber cross-sectional areas by ~35-55% in both EH and NH. This response to clenbuterol treatment was not significantly different between EH and NH diaphragm. In EH, twitch force (P t ), maximal tetanic force, and force-frequency curve were significantly reduced compared with NH. In EH, clenbuterol increased P t by ~10%, restoring P t to NH level. A similar improvement was observed in the force-frequency characteristics. Clenbuterol did not alter contractile properties in NH. In conclusion, long-term clenbuterol treatment resulted in an increased size of all diaphragm muscle fiber types in both NH and EH. Clenbuterol completely abolished the reduced force generation induced by emphysema. contractile properties; -adrenergic agonists; respiratory muscles; myosin heavy chains; emphysema