Chick J J, Stephenson D G
Department of Zoology, La Trobe University, Bundoora, Victoria, Australia.
J Muscle Res Cell Motil. 1995 Jun;16(3):285-94. doi: 10.1007/BF00121137.
The effect of temperature (5-35 degrees C) on maximum force production was examined in intact and chemically skinned muscle fibre bundles (10-25 fibres) from the anterior byssus retractor muscle of Mytilus edulis. In intact fibre bundles, 10 microM acetylcholine induced a tonic contraction which had a magnitude of 65.4 +/- 4.0 N cm-2 (n = 30) at 23 degrees C. Activation by caffeine (20 mM) produced a force response which was 157.1 +/- 7.9% (n = 16) of the acetylcholine response at 23 degrees C and acetylcholine and caffeine together produced force which was not significantly different from the response to caffeine alone. At 5 degrees C the acetylcholine and caffeine responses were decreased by 9.6 +/- 3.4% (n = 6) and 14.6 +/- 2.8% (n = 8) compared with the respective responses at 23 degrees C. However, there was no significant reduction of the response induced by the combined action of acetylcholine and caffeine when the temperature was decreased from 23 degrees C to 5 degrees C. The 20-80% of peak force activation time increased by about one order of magnitude for all acetylcholine, caffeine and combined acetylcholine-caffeine-induced responses when the temperature was decreased from 23-5 degrees C. Repeated exposure of the intact preparation to caffeine caused a marked decrease in the caffeine-induced response (complete abolition of force after the third exposure to caffeine), but the response to caffeine could be fully restored following one acetylcholine-induced activation. The maximum Ca(2+)-activated force after skinning the preparation with saponin was not significantly different from the caffeine or combined acetylcholine-caffeine-induced responses before skinning. In the saponin skinned fibre preparation a drop in temperature from 23 degrees C to 15 degrees C or 5 degrees C decreased the maximum Ca(2+)-activated force by 13.2 +/- 1.4% (n = 8) and 41.4 +/- 3.1% (n = 5) respectively. The activation time between 20-80% of the peak Ca(2+)-activated force increased at 15 degrees C and 5 degrees C by a factor of 1.5 +/- 0.1 (n = 5) and 6.8 +/- 1.1 (n = 5) respectively when compared to corresponding values at 23 degrees C. The relaxation half-time decreased by a factor of 1.7 +/- 0.2 (n = 5) and 3.0 +/- 0.2 (n = 5) at 15 degrees C and 5 degrees C respectively compared with that at 23 degrees C.(ABSTRACT TRUNCATED AT 400 WORDS)
研究了温度（5 - 35摄氏度）对紫贻贝前足丝牵缩肌完整和化学去膜肌纤维束（10 - 25根纤维）最大产力的影响。在完整纤维束中，10微摩尔乙酰胆碱诱导强直收缩，在23摄氏度时收缩幅度为65.4±4.0牛/平方厘米（n = 30）。咖啡因（20毫摩尔）激活产生的力反应是23摄氏度时乙酰胆碱反应的157.1±7.9%（n = 16），乙酰胆碱和咖啡因共同作用产生的力与单独咖啡因反应无显著差异。与23摄氏度时各自反应相比，5摄氏度时乙酰胆碱和咖啡因反应分别降低了9.6±3.4%（n = 6）和14.6±2.8%（n = 8）。然而，当温度从23摄氏度降至5摄氏度时，乙酰胆碱和咖啡因联合作用诱导的反应无显著降低。当温度从23摄氏度降至5摄氏度时，所有乙酰胆碱、咖啡因以及乙酰胆碱 - 咖啡因联合诱导反应的20 - 80%峰值力激活时间增加了约一个数量级。完整制剂反复暴露于咖啡因会导致咖啡因诱导反应显著降低（第三次暴露于咖啡因后力完全消失），但乙酰胆碱诱导激活一次后，对咖啡因的反应可完全恢复。用皂角苷去膜制剂后，最大钙激活力与去膜前咖啡因或乙酰胆碱 - 咖啡因联合诱导反应无显著差异。在皂角苷去膜纤维制剂中，温度从23摄氏度降至15摄氏度或5摄氏度时，最大钙激活力分别降低了13.2±1.4%（n = 8）和41.4±3.1%（n = 5）。与23摄氏度时相应值相比，15摄氏度和5摄氏度时20 - 80%峰值钙激活力之间的激活时间分别增加了1.5±0.1倍（n = 5）和6.8±1.1倍（n = 5）。与23摄氏度时相比，15摄氏度和5摄氏度时松弛半衰期分别降低了1.7±0.2倍（n = 5）和3.0±0.2倍（n = 5）。（摘要截断于400字）
