酸碱度对蟾蜍离体腓肠肌收缩能力的影响

Effects of pH on contractility of toad gastrocnemius muscle

目的研究肌肉疲劳产生的生理学机制,寻找提高人体运动能力的方法和措施,观察了酸碱度对蟾蜍离体腓肠肌收缩能力的影响。方法采用D951生理实验教学系统,记录分析了置于pH值为6.2,6.4,6.6,6.8,7.0,7.2,7.4,7.6,7.8林格液中的蟾蜍离体腓肠肌(n=94)的单收缩曲线。结果(1)蟾蜍腓肠肌收缩能力最佳的pH值为6.8～7.2;(2)pH值在7.4～7.8时,肌肉在初期出现强直收缩,且pH值越高,强直收缩的持续时间越长。(3)随肌肉收缩的不断进行,舒张期时间逐渐延长,缩短期时间不变。结论蟾蜍腓肠肌在pH6.8～7.2之间收缩能力最佳。pH值过高或过低都将导致肌肉的收缩能力下降。肌肉舒张能力的降低是肌肉疲劳的主要特征之一。为防止肌肉疲劳应提高人体对酸的缓冲能力,但碱性物质的过量补充也可导致肌肉收缩能力下降,且易导致运动初期肌肉的强直性收缩。

Aim To explore the physiological mechanism of muscle fatigue for the methods and measures enhancing the performance ability, and observe the effects of different pH on contractility of toad gastrocnemius muscle.Methods The single contraction curves of toad gastrocnemius muscles(n=94) stimulated continuously(912ms, 7.5V) in Ringer solutions of different pH(6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6, 7.8￡(c)were recorded and analyzed respectively with D95 SUPER LAB SYSTEM. Results (1) The pH range of optimal contractility of toad gastrocnemius muscle was 6.8-7.2. (2) The tetanic contraction appeared in the initial stages of the muscle contraction in the pH range from 7.4 to 7.8, the higher of the pH value, the longer of tetanic contraction duration. (3) The duration of muscle relaxation prolongs gradually with the muscle contraction proceeding, but the duration of shorting unchanging.Conclusion The optimal pH range for toad gastrocnemius muscle contraction is 7.4-7.8. The contractility of the muscle drops in the pH over or under the range. The main character of muscle fatigue is reduction of muscle relaxing ability. It is suggested that the buffer storage to acid must be enriched in order to improve the performance ability. But the over supplementof alkali substances also reduces the contractility of toad gastrocnemius muscle and induces the tetanic contraction in the initial stages of the muscle contraction.