title: Effect of lung fibrosis on glycogen content in different extrapulmonary tissues.
abstract: OBJECTIVE
  Patients with pulmonary fibrosis often exhibit reduced lung function and diminished health-related quality of life. Studies have shown that paraquat-induced, extrapulmonary, acute lung injury affects the metabolic profile of glycogen content in different tissues. The purpose of the present study was to investigate whether the process of pulmonary fibrosis induced by continuous exposure to the toxic herbicide paraquat or by a local insult from bleomycin affects the glycogen content in tissues.
  
  
  METHODS
  In the paraquat experiment, Wistar rats (n = 5 per group) received either saline (controls) or an intraperitoneal injection of a paraquat solution (7.0 mg/kg; experimental group) once a week for 4 weeks. In the bleomycin experiment, Balb/c mice (n = 5 per group) received either saline (controls) or 6.25 U/kg of bleomycin through intratracheal instillation in single dose (experimental group). Glycogen content in different tissues (mg/g tissue) was measured using the anthrone reagent. The lungs submitted to histopathological and quantitative analyses of fibrosis.
  
  
  RESULTS
  Paraquat-induced fibrosis led to lower glycogen content in the gastrocnemius muscle (2.7 ± 0.1 vs. 3.4 ± 0.1; 79 %) compared with the controls, whereas no changes in glycogen content were found in the diaphragm or heart. Bleomycin-induced fibrosis led to lower glycogen content in the diaphragm (0.43 ± 0.02 vs. 0.79 ± 0.09, 54 %), gastrocnemius muscle (0.62 ± 0.11 vs. 1.18 ± 0.06, 52 %), and heart (0.68 ± 0.11 vs. 1.39 ± 0.1, 49 %) compared with the controls (p < 0.05). Moreover, the area of fibrous connective tissue (μm(2)) in the lungs was significantly increased in paraquat-induced fibrosis (3,463 ± 377 vs. 565 ± 89) and bleomycin-induced fibrosis (3,707 ± 433.9 vs. 179 ± 51.28) compared with the controls.
  
  
  CONCLUSIONS
  The findings suggest that the effects of fibrogenesis in the lungs are not limited to local alterations but also lead to a reduction in glycogen content in the heart and other muscles. This reduction could partially explain the impaired muscle performance found in patients with pulmonary fibrosis.
authors.affiliation: Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-010, Brazil, borgesel@icb.ufmg.br.
authors.forename: Elizabeth Lage
authors.initials: EL
authors.lastname: Borges
authors.forename: Marina
authors.initials: M
authors.lastname: de Barros Pinheiro
authors.forename: Luana Oliveira
authors.initials: LO
authors.lastname: Prata
authors.forename: Wesley Araújo
authors.initials: WA
authors.lastname: Sales
authors.forename: Yuri Augusto Junqueira Belém
authors.initials: YA
authors.lastname: Silva
authors.forename: Marcelo Vidigal
authors.initials: MV
authors.lastname: Caliari
authors.forename: Maria Glória
authors.initials: MG
authors.lastname: Rodrigues-Machado
authors.forename: Maria
authors.initials: M
authors.lastname: da Glória Rodrigues-Machado
mesh_terms: D000818:Animals; D001761:Bleomycin; D003964:Diaphragm / Q000378:metabolism*; D004195:Disease Models, Animal; D006003:Glycogen / Q000378:metabolism*; D008168:Lung / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010269:Paraquat; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001761:Bleomycin; D006003:Glycogen; D010269:Paraquat