Register      Login
Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology
RESEARCH ARTICLE

Rat diaphragm during postnatal development. II. Resistance to low- and high-frequency fatigue

MD Fratacci, M Levame, A Rauss and G Atlan

Reproduction, Fertility and Development 8(3) 399 - 407
Published: 1996

Abstract

The effects on the rat diaphragm of fatigue induced by low- and high-frequency stimulation (at 5 Hz for 1.5 min and 75 Hz for 1 min) were examined during postnatal development. Experiments were performed on isolated costal diaphragm strips. Before stimulation, twitch contraction time and half relaxation time were longest in the neonate and decreased significantly between weeks 1 and 6. Correspondingly, the specific twitch tension (corrected for cross-sectional area) increased progressively with age. After either low- or high-frequency fatigue, the force recovery was complete in 1- and 2-week-old rats, whereas the force production progressively decreased in older rats. In addition, the neonate diaphragm further enhanced its force selectively after high-frequency fatigue. It is concluded that the rat diaphragm is comparably resistant to fatigue during the early postnatal period, whether fatigue is induced by low- or by high-frequency stimulation. This suggests that postnatal changes in diaphragm contractile and fatigue properties may be related to changes in the process of force production. The possibility is discussed that a higher total muscle oxidative potential and the mechanisms leading to force potentiation in the neonate might explain the fatigue resistance.

https://doi.org/10.1071/RD9960399

© CSIRO 1996

Committee on Publication Ethics


Export Citation Get Permission

View Dimensions