TEMPERATURE-DEPENDENCE OF MAMMALIAN MUSCLE CONTRACTIONS AND ATPASE ACTIVITIES
TEMPERATURE-DEPENDENCE OF MAMMALIAN MUSCLE CONTRACTIONS AND ATPASE ACTIVITIES
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DOI：
10.1016/s0006-3495(82)84464-0
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发表时间：
1982-01-01
影响因子：
3.4
通讯作者：
SHRIVER, J
中科院分区：
文献类型：
--
作者：
STEIN, RB;GORDON, T;SHRIVER, J
在等长和等张条件下，在温度约为40 ℃下研究了分离的大鼠和小鼠趾长伸肌（EDL）和比目鱼肌。8度38.degree. C.在等长强直期间张力指数上升的速率常数具有约的Q10。2.5对于所有肌肉（对应于激活焓，**），图形 **。= 66 kJ/mol，如果速率由单一化学反应确定）。半收缩时间、收缩时间、等长收缩中张力的最大上升速率和等张收缩中的最大缩短速度都具有类似的温度依赖性（即，.**图形 **。. apprx. 66 kJ/mol）。从大鼠趾长伸肌和比目鱼肌制备的肌原纤维的Mg 2 + ATP酶速率具有更陡的温度依赖性。图形 **。= 130 kJ/mol），但在20 ℃时绝对速率为100 kJ/mol。C均低于张力上升速率。Mg 2 + ATP酶循环速率对力的产生没有限制。横桥的相当一部分可能存在于静止状态，其以比完成循环和重新填充静止状态所需的更快的速率转化为力产生状态。在等长抽搐或短强直（以及抽搐的半下降时间）期间，张力的指数衰减的速率常数的温度依赖性在λ处具有断点。20.degree. C，表观焓值为.**图形 **。= 117 kJ/mol C和.**图形 **。= 70 kJ/mol C.断点和.** 的值图形 **。在高温和低温下与公布的值密切一致。**图形 **。肌浆网（SR）Ca ~（2+）ATP酶的活性。温度依赖性的弛豫速率的抽搐或短强直是一致的，为钙离子的重吸收率进入SR。
Isolated rat and mouse extensor digitorum longus (EDL) and soleus muscles were studied under isometric and isotonic conditions at temperatures from .apprx. 8.degree.-38.degree. C. The rate constant for the exponential rise of tension during an isometric tetanus had a Q10 of .apprx. 2.5 for all muscles (corresponding to an enthalpy of activation, .**GRAPHIC**. = 66 kJ/mol, if the rate was determined by a single chemical reaction). The half-contraction time, contraction time, maximum rate of rise for tension in an isometric twitch and the maximum shortening velocity in an isotonic contraction all had a similar temperature dependence (i.e., .**GRAPHIC**. .apprx. 66 kJ/mol). The Mg2+ ATPase rates of myofibrils prepared from rat EDL and soleus muscles had a steeper temperature dependence .**GRAPHIC**. = 130 kJ/mol), but absolute rates at 20.degree. C were lower than the rate of rise of tension. The Mg2+ ATPase cycle rate is not limiting for force generation. A substantial fraction of cross-bridges may exist in a resting state that converts to the force-producing state at a rate faster than required to complete the cycle and repopulate the resting state. The temperature dependence for the rate constant of the exponential decay of tension during an isometric twitch or short tetanus (and the half-fall time of a twitch) had a break point at .apprx. 20.degree. C, with apparent enthalpy values of .**GRAPHIC**. = 117 kJ/mol below 20.degree. C and .**GRAPHIC**. = 70 kJ/mol above 20.degree. C. The break point and the values of .**GRAPHIC**. at high and low temperatures agree closely with published values for the .**GRAPHIC**. of the sarcoplasmic reticulum (SR) Ca2+ ATPase. The temperature dependence for the relaxation rate of a twitch or a short tetanus is consistent with that for the reabsorption rate of Ca2+ into the SR.