甲状腺ホルモンがラットヒラメ筋における筋小胞体のCa^<2+>取り込みおよび収縮特性に及ぼす影響  [in Japanese] EFFECTS OF THYROID HORMONE ON SARCOPLASMIC RETICULUM Ca^<2+> UPTAKE AND CONTRACTILE PROPERTIES IN RAT SOLEUS MUSCLE  [in Japanese]

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Author(s)

Abstract

The effect of hyperthyroidism on the contractile properties and Ca<SUP>2+</SUP> sequestering abilities by the sarcoplasmic reticulum (SR) in the soleus muscles was examined in rats treated with thyroid hormone (3, 5, 3'-triiodo-L-thyronine, T<SUB>3</SUB>) (300μg/kg body weight) for 3, 7 and 21 days. At the end of a given treatment period, the right or left soleus muscle was mounted isometrically at 30°C, and stimulated directly using supramaximal current intensity. A twitch contraction was elicited by a 1 msec square-wave pulse and a tetanic contraction by 20 Hz stimulation for 600 msec. To evaluate fatigue resistance, muscles were stimulated at 40 Hz for 350 msec with tetani repeated at an interval of 2 sec during a 4-min period. Another soleus muscle was used, for analysis of SR Ca<SUP>2+</SUP> -uptake rate and SR Ca<SUP>2+</SUP> -ATPase activity. Pronounced increases in SR Ca<SUP>2+</SUP> -uptake rate and ATPase activity were observed after T<SUB>3</SUB> treatment periods longer than 6 days. These alterations were accompanied by decreases in twitch and tetanic tension, half-relaxation time, and fatigue resistance. The T<SUB>3</SUB>-treated muscles stimulated at 20 Hz relaxed during the interval between successive stimuli, indicating that the mechanical fusion of tetanic contractions was incomplete. SR Ca<SUP>2+</SUP> uptake rate was significantly correlated both to tetanic tension and to fatigue resistance. These data suggest that there may be a causal relationship between changes in SR Ca<SUP>2+</SUP> uptake and the loss of muscular strength in the hyperthyroid soleus.

Journal

  • Japanese Journal of Physical Fitness and Sports Medicine

    Japanese Journal of Physical Fitness and Sports Medicine 53(5), 509-518, 2004-10-01

    The Japanese Society of Physical Fitness and Sport Medicine

References:  20

Codes

  • NII Article ID (NAID)
    110001915734
  • NII NACSIS-CAT ID (NCID)
    AN00137986
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    0039906X
  • NDL Article ID
    7121338
  • NDL Source Classification
    ZF21(教育--体育)
  • NDL Call No.
    Z7-301
  • Data Source
    CJP  NDL  NII-ELS  IR  J-STAGE 
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