Effects of postnatal maturation on energetics and cross-bridge properties in rat diaphragm.
The effects of maturation on cross-bridge (CB) properties were studied in rat diaphragm strips obtained at postnatal days 3, 10, and 17 and in adults (10-12 wk old). Calculations of muscle energetics and characteristics of CBs were determined from standard Huxley equations. Maturation did not change the curvature of the force-velocity relationship or the peak of mechanical efficiency. There was a significant increase in the total number of CBs per cross-sectional area (m) with aging but not in single CB force. The turnover rate of myosin ATPase increased, the duration of the CB cycle decreased, and the velocity of CBs decreased significantly only after the first week postpartum. There was a linear relationship between maximum total force and m (r = 0.969, P < 0.001), and between maximum unloaded shortening velocity and m (r = 0.728, P < 0.001). When this study in the rat and previous study in the hamster are compared, it appears that there are few species differences in the postnatal maturation process of the diaphragm.
Orliaguet
Gilles
G
Department of Anesthesiology and Critical Care, Centre Hospitalo-Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, Université Paris V 75743 Paris Cedex 15, France. gorlia@club-internet.fr
Langeron
Olivier
O
Bouhemad
Belaid
B
Coriat
Pierre
P
LeCarpentier
Yves
Y
Riou
Bruno
B
D000205:Actomyosin / Q000502:physiology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development*; D003964:Diaphragm / Q000502:physiology*; D004734:Energy Metabolism; D009119:Muscle Contraction / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D015656:Respiratory Mechanics; D013997:Time Factors
D000205:Actomyosin