Dynamic response of the isolated passive rat diaphragm strip

• DOI: 10.1152/jappl.1992.73.6.2681
• Publication Date: 2017-12-21T17:59:03Z
• Authors: D. Navajas; S. Mijailovich; G. M. Glass; D. Stamenovic; J. J. Fredberg
• Keywords: Diaphragm (acoustics)

To further our understanding of the mechanisms underlying chest wall mechanics, we investigated dynamic response isolated passive rat diaphragm strip. Stress adaptation tissue was measured from 0.05 to 60 s after subjecting strips strain steps normalized amplitudes 0.005 0.04. The resistance (R), elastance (E), and hysteresivity (eta) were in same range by sinusoidally straining strip at frequencies 0.03125 10 Hz. stress (T) depended exponentially on (epsilon) relaxed recovered linearly with logarithm time. E increased frequency decreased increasing amplitude. R fell hyperbolically showed an amplitude dependence similar that E. interpret strong nonlinear behavior, extended viscoelastic model Hildebrandt (J. Appl. Physiol. 28: 365–372, 1970) include exponential stress-strain relationship. Accordingly, step described T - Tr = Tr(e alpha delta epsilon 1)(1 gamma log t), where is amplitude, initial operating stress, a measure nonlinearity, rate adaptation. oscillatory computed applying Fung's quasi-linear theory. This fitted data fairly well but only if negatively epsilon, as might be expected plastic material.