title: Paraquat (PQ)-induced pulmonary fibrosis increases exercise metabolic cost, reducing aerobic performance in rats.
abstract: Rats exposed to the quaternary herbicide paraquat (PQ) exhibit oxidative stress and lung injury. In the present study, we investigated the effect of multiple exposures to PQ on aerobic performance during progressive exercise on a treadmill in rats. PQ was dissolved in saline (SAL) (10 mg/ml) and administered intraperitoneally 7 mg/kg body wt to Wistar rats (n = 5) once a week for one month. Control rats received SAL (0.7 ml/kg body wt., intraperitoneally, n = 5) over the same time period. The animals were submitted to aerobic evaluation on a treadmill using a progressive protocol until fatigue prior to the administration of the first dose of PQ or SAL and repeated at 1 week and 40 days following the last dose of the herbicide. Twenty-four hours after the last performance tests, the animals were sacrificed, lungs removed and divided in two groups: PQ and SAL for histopathological analysis. The animals exposed to PQ exhibited decrease in aerobic performance and mechanical efficiency (ME) as well as increase in oxygen consumption during exercise in comparison to the controls forty days after the last dose of PQ. Lung histologic changes included atelectasis, interstitial edema, and inflammation cells in PQ group. The collagen system fibers, fraction area of alveolar collapse and influx of polymorphonuclear (PMN) cells in lung parenchyma were higher in PQ compared to SAL. In conclusion, multiple exposures to PQ induce pulmonary fibrosis, reduce the aerobic performance and mechanical efficiency and increase the metabolic cost of exercise in rats.
authors: Faculty of Biological and Healthy Sciences, Federal University of the Jequitinhonha and Mucuri Valleys, Diamantina, MG, Brazil. lacerda.acr@ufvjm.edu.br
authors: Ana Cristina Rodrigues
authors: AC
authors: Lacerda
authors: Maria da Glória
authors: Mda G
authors: Rodrigues-Machado
authors: Polyana Leite
authors: PL
authors: Mendes
authors: Rômulo Dias
authors: RD
authors: Novaes
authors: Giovanna Marcella Cavalcante
authors: GM
authors: Carvalho
authors: Walter Araujo
authors: WA
authors: Zin
authors: Fernando
authors: F
authors: Gripp
authors: Cândido Celso
authors: CC
authors: Coimbra
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D006540:Herbicides / Q000008:administration & dosage / Q000633:toxicity*; D007274:Injections, Intraperitoneal; D008297:Male; D018384:Oxidative Stress; D010101:Oxygen Consumption / Q000187:drug effects*; D010269:Paraquat / Q000008:administration & dosage / Q000633:toxicity*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011658:Pulmonary Fibrosis / Q000139:chemically induced* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D006540:Herbicides; D010269:Paraquat