摘要:

AbstractThe aim of this study was to investigate the contractile protein characteristics after 5‐day (Cosmos 1514) and 7‐day (Cosmos 1667) spaceflights. The experiments were performed on skinned fibers from the soleus, gastrocnemius lateralis, and plantaris muscles isolated from Wistar rats. A reduction in fiber diameter might explain the decrease in the maximal tension in the soleus, whereas this tension was unaltered in the gastrocnemius and the plantaris. Moreover the calcium sensitivity of the myofilament appeared modified in the soleus and in the gastrocnemius: The tension/pCa relationships were shifted toward higher calcium concentrations, indicating a decrease in the appearent calcium binding constant of the tropinin C. The tension/pCa relationship appeared unaltered in the plantaris after spaceflight. Finally, the studies of the time to reach a steady tension indicated an increase in the rate of force development in the soleus and, on the contrary, a slowing down in the plantaris. No change in the gastrocnemius was found. The results were analyzed with references to the different muscle functions in disuse atro

ISSN:0148-639X    

DOI:10.1002/mus.880140112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractMaximum M‐waves (muscle compound action potentials) were studied in the abductor pollicis brevis (APB), extensor digitorum brevis (EDB), and tibialis anterior (TA) muscles of 12 patients with myotonic muscular dystrophy (MMD) and in the same number of control subjects, matched for age and sex. The peak‐to‐peak amplitudes and voltage‐time areas of the responses were measured at rest, between 40 maximum voluntary contractions (each lasting 3 s) and also during a 2‐min recovery period. In 34 of the 36 control muscles the M‐waves potentiated during the period of intermittent voluntary contractions. In the MMD patients, however, the M waves exhibited initial declines in 25 of 30 muscles. In the APB and EDB muscles the normalized mean values for the smallest M‐waves, recorded during the 350 s total observation periods, differed significantly between the 2 groups of subjects. It is suggested that the sarcolemmal Na+‐K+pump has a raised threshold for activation

ISSN:0148-639X    

DOI:10.1002/mus.880140113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880140114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880140115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880140116

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880140117

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880140101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY