Saeki Y, Kato C, Horikoshi T, Yanagisawa K
Arch Oral Biol. 1984;29(9):663-8. doi: 10.1016/0003-9969(84)90169-9.
At a muscle length, L0 (just taut), isometric tension and tension transients in response to rapid step stretches in length (less than 1 per cent of L0 within 2 ms) were measured at constant levels of Ca2+ activation of various magnitudes in glycerinated temporal and masseter muscles (1.7-2.5 mm long, 48-96 micron in diameter) from guinea pigs. The experiments were at 20 and 30 degrees C, and pH 6.8. Steady isometric tension increased in a sigmoid fashion as Ca2+ varied from about pCa 6.6 to 4.4 in both muscles. However, the maximum tension of temporal muscle was about 4.4 times greater than that of masseter muscle at 20 degrees C. The tension transients showed an immediate tension increase coincident with the stretch (the first phase) and an exponential-like tension decrease (the second phase). The time constant of the second phase was about 87.5 ms in temporalis and 3.7 ms in masseter at 30 degrees C. Decreasing temperature from 30 to 20 degrees C markedly increased the time constant of the tension response in the second phase (Q10 of about 3.4 in temporalis and 2.2 in masseter). Although there was a difference in the sarcomere length between the two muscles at L0 (2.14 micron in temporalis and 1.84 micron in masseter), the mechanical characteristics were almost independent of the muscle length. Thus the cross-bridges in temporalis appear to cycle more slowly and produce more isometric tension than those in masseter muscle.
在肌肉长度L0（刚好绷紧）时，在不同程度的Ca2+激活水平下，对豚鼠甘油化的颞肌和咬肌（长1.7 - 2.5毫米，直径48 - 96微米），于20和30摄氏度、pH 6.8的条件下，测量其等长张力以及对长度快速阶跃拉伸（2毫秒内长度变化小于L0的1%）的张力瞬变。随着Ca2+在两种肌肉中从约pCa 6.6变化到4.4，稳定等长张力呈S形增加。然而，在20摄氏度时，颞肌的最大张力约为咬肌的4.4倍。张力瞬变表现为与拉伸同时出现的即时张力增加（第一阶段）和类似指数的张力下降（第二阶段）。在30摄氏度时，第二阶段的时间常数在颞肌中约为87.5毫秒，在咬肌中约为3.7毫秒。将温度从30摄氏度降至20摄氏度显著增加了第二阶段张力反应的时间常数（颞肌的Q10约为3.4，咬肌的Q10约为2.2）。尽管在L0时两种肌肉的肌节长度存在差异（颞肌为2.14微米，咬肌为1.84微米），但其力学特性几乎与肌肉长度无关。因此，颞肌中的横桥似乎比咬肌中的横桥循环更慢，产生的等长张力更大。
