Developmental changes in crossbridge properties and myosin isoforms in hamster diaphragm.
Am J Respir Crit Care Med
; 156(3 Pt 1): 959-67, 1997 Sep.
Article
em En
| MEDLINE
| ID: mdl-9310020
ABSTRACT
The aim of this study was to determine the effects of maturation on crossbridge properties and myosin isoform composition in hamster diaphragm muscle. Diaphragm strips were obtained at postnatal Days 1 and 8 and in adults (10 to 12 wk). Peak isometric tension and maximum unloaded shortening velocity (Vmax) increased with age (p < 0.001). The single crossbridge force (pi), the total number of crossbridges normalized per cross-sectional area (m x 10(9)/mm2), the turnover rate of myosin ATPase (kcat), and peak mechanical efficiency (Effmax) were calculated from Huxley's equations. The value of m increased significantly from birth to adulthood (p < 0.001), with no changes in pi or Effmax; kcat increased significantly only after the first week postpartum. There was a strong linear relationship between peak isometric tension and m (p < 0.001). Conversely, changes in Vmax were not related to kcat. Myosin electrophoresis showed that neonatal bands and slow myosin isoforms (S) were present at birth. The number of fast adult myosin isoforms increased progressively from birth to adulthood, whereas S increased during the first week postpartum. In conclusion, development changes in diaphragm muscle force and myosin isoform composition were associated with changes in crossbridge number and kinetics, with no changes in the average force per crossbridge or in mechanical efficiency.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Diafragma
/
Mesocricetus
/
Miosinas
/
Desenvolvimento Muscular
/
Animais Recém-Nascidos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Am J Respir Crit Care Med
Assunto da revista:
TERAPIA INTENSIVA
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
França