Different ontogeny of rate of force generation and shortening velocity in guinea pig trachealis.

Published

Journal Article

Juveniles of many species, including humans, display greater airway responsiveness than do adults. This may involve changes in airway smooth muscle function. In the present work we studied force production and shortening velocity in trachealis from 1-wk-old (1 wk), 3-wk-old (3 wk), and 3-mo-old (adult) guinea pigs. Strips were electrically stimulated (60 Hz, 18 V) at their optimal length (l(o)) to obtain maximum active stress (P(o)) and rate of stress generation. Then, force-velocity curves were elicited at 2.5 s from the onset of the stimulus. By applying a recently developed modification of Hill's equation for airway smooth muscle, the maximum shortening velocity at zero load (V(o)) and the value alpha. gamma/beta, an index of internal resistance to shortening (Rsi), were calculated (alpha, beta, and gamma are the constants of the equation). P(o) increased little with maturation, whereas the rate of stress generation increased significantly (0.40 +/- 0.03, 0.45 +/- 0.03, 0. 51 +/- 0.03 P(o)/s for 1 wk, 3 wk, and adult animals). V(o) slightly increased early with maturation to decrease significantly later (1. 79 +/- 0.67, 2.45 +/- 0.92, and 0.55 +/- 0.09 l(o)/s for 1 wk, 3 wk, and adult animals), whereas the Rsi showed an opposite trend (14.98 +/- 5.19, 8.99 +/- 3.01, and 32.07 +/- 5.54 mN. mm(-2). l(o)(-1). s for 1 wk, 3 wk, and adult animals). This early increase of force generation in combination with late increase of Rsi may explain the changes of V(o) with age. An elevated V(o) may contribute to the incidence of airway hyperresponsiveness in healthy juveniles.

Full Text

Duke Authors

Cited Authors

  • Chitano, P; Wang, J; Cox, CM; Stephens, NL; Murphy, TM

Published Date

  • April 2000

Published In

Volume / Issue

  • 88 / 4

Start / End Page

  • 1338 - 1345

PubMed ID

  • 10749828

Pubmed Central ID

  • 10749828

Electronic International Standard Serial Number (EISSN)

  • 1522-1601

International Standard Serial Number (ISSN)

  • 8750-7587

Digital Object Identifier (DOI)

  • 10.1152/jappl.2000.88.4.1338

Language

  • eng