Mechanical properties of mouse distal lung: in vivo versus in vitro comparison.
While measurements of lung tissue mechanics have been made in several species, relatively little has been reported in the mouse. Moreover, whether in vivo measurements truly reflect tissue properties is somewhat controversial. We measured complex impedance of the mouse respiratory system in vivo using a ventilator, which applies a multiple frequency volume signal to the airway opening. A constant phase model was fit to the impedance data, yielding parameters for tissue damping (G) and elastance (H). Hysteresivity (eta) was calculated as G/H. Quasistatic pressure-volume (P-V) curves were obtained during deflation. In vitro measurements of complex impedance and stress-strain curves were made in lung tissue strips. Values of eta were significantly higher in vivo than in vitro (0.111 +/- 0.004 versus 0.042 +/- 0.003). The higher values of eta in vivo may represent the effects of airway heterogeneities, surfactant, or changes in alveolar geometry. Measurement of mechanics in the tissue strip offers a better assessment of pure tissue properties.
Meakins Christie Laboratories, McGill University, 3626 St. Urbain Street, Montreal, Que., Canada H2X 2P2.
Anita
A
Fust
Jason H T
JH
Bates
Mara S
MS
Ludwig
D000818:Animals; D017097:Electric Impedance; D005260:Female; D066298:In Vitro Techniques; D008168:Lung / Q000502:physiology*; D008297:Male; D051379:Mice; D015656:Respiratory Mechanics