title: Overexpression of TGF-alpha increases lung tissue hysteresivity in transgenic mice.
abstract: Increased transforming growth factor (TGF)-alpha has been observed in neonatal chronic lung disease. Lungs of transgenic mice that overexpress TGF-alpha develop enlarged air spaces and pulmonary fibrosis compared with wild-type mice. We hypothesized that these pathological changes may alter the mechanical coupling of viscous and elastic forces within lung parenchyma. Respiratory impedance was measured in open-chested, tracheostomized adult wild-type and TGF-alpha mice by using the forced oscillation technique (0.25-19.63 Hz) delivered by flexiVent (Scireq, Montreal, PQ). Estimates of airway resistance (Raw), inertance (I), and the coefficients of tissue damping (G(L)) and tissue elastance (H(L)) were obtained by fitting a model to each impedance spectrum. Hysteresivity (eta) was calculated as G(L)/H(L). There was a significant increase in eta (P < 0.01) and a trend to a decrease in H(L) (P = 0.07) of TGF-alpha mice compared with the wild-type group. There was no significant change in Raw, I, or G(L). Structural abnormality present in the lungs of adult TGF-alpha mice alters viscoelastic coupling of the tissues, as evidenced by a change in eta.
authors.affiliation: TVW Telethon Institute for Child Health Research, West Perth 6872, WA, Australia. j.pillow@ich.ucl.ac.uk
authors.forename: J J
authors.initials: JJ
authors.lastname: Pillow
authors.forename: T R
authors.initials: TR
authors.lastname: Korfhagen
authors.forename: M
authors.initials: M
authors.lastname: Ikegami
authors.forename: P D
authors.initials: PD
authors.lastname: Sly
mesh_terms: D000403:Airway Resistance / Q000187:drug effects*; D000818:Animals; D004548:Elasticity; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008170:Lung Compliance; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics; D008954:Models, Biological; D012016:Reference Values; D015656:Respiratory Mechanics; D014139:Tracheostomy; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000494:pharmacology*; D014783:Viscosity
chemical_list: D016211:Transforming Growth Factor alpha