Temperature dependence of contraction characteristics in developing rat muscles
Temperature dependence of contraction characteristics in developing rat muscles
复制标题
发育中的大鼠肌肉收缩特性的温度依赖性
作者：
PhD S. R. WYUE;PhD K. W. RANATUNGA;Brislo England;J. Wiley
采用直接刺激和不同温度(35~10℃)对不同周龄大鼠指长伸肌(EDL)和比目鱼肌(SOL)的收缩进行了研究。4周龄EDL肌的收缩张力在35℃至20℃的降温过程中增加，在20℃以下进一步降温时张力降低。这种收缩张力的温度依赖性模式在所有年龄的快速肌中均可见。4周龄SOL肌在35~10℃降温(降温凹陷)时，收缩张力单调下降。这种降温模式在年轻的SOL肌肉中并不明显。1周龄SOL肌收缩张力的温度依赖关系有明显的滞后现象。在1周龄和4周龄时，EDL和SOL肌的张力均受到低温的抑制。结果表明，快肌纤维在幼龄(1周)时与收缩活动有关的突起几乎完全发育，而慢肌纤维则发育较晚。
Contractions of rat extensor digitorum longus (EDL, a fast muscle) and soleus (SOL, a slow muscle muscles of different ages 1–4 weeks) were recorded in vitro with direct stimulation and at different temperatures (range 35–10°C). Twitch tension in 4‐week‐old EDL muscle increased in cooling from 35 to 20°C (cooling potentiation); the tension decreased in further cooling below 20°C. This pattern of temperature dependence of twitch tension was seen in fast muscles of all ages (1–4 weeks). Twitch tension in 4‐week‐old SOL muscle decreased monotonically in cooling from 35 to 10°C (cooling depression). This pattern of cooling depression was not clearly evident in younger SOL muscles. There was a marked hysteresis in the temperature dependence of twitch tension in the 1‐week‐old SOL muscles. Tetanic tension was depressed by low temperature in both EDL and SOL muscles at 1 week and at 4 weeks of age. Results show that the processes concerned with contractile activation are nearly fully developed in the fast muscle fibers at an early age (1 week), whereas they develop later in the slow muscle fibers.