Mechanism of contracture on cooling of caffeine‐treated frog skeletal muscle fibres.
Mechanism of contracture on cooling of caffeine‐treated frog skeletal muscle fibres.
复制标题
咖啡因处理的青蛙骨骼肌纤维冷却的结构机制。
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
caffeine
中科院分区：
文献类型：
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作者：
K. Horiuti;caffeine
1.为了阐明挛缩对咖啡因处理的完整肌纤维冷却的机制，在去皮的青蛙肌纤维中检查了肌浆网（SR）的钙（Ca 2+）释放机制（“Ca 2+诱导的Ca 2+释放”）的温度依赖性。2.在含有1.2 mM-咖啡因和0.7 mM-EGTA（Mg 2+，1.5 mM，Mg-ATP，3.5 mM，pH 7）的溶液中的剥皮纤维在冷却（从22 ° C至2 ° C）时由于SR中的Ca 2+释放而收缩。在各种条件下使用“咖啡因法”测定在含有Ca 2+离子（具有10 mM-EGTA）且不含ATP盐的培养基中从去皮纤维SR释放Ca 2+的速率。' 4.在不存在Mg 2+离子、腺嘌呤核苷酸和咖啡因的情况下，在SR外部的任何浓度的Ca 2+离子下，室温（21 - 22摄氏度）下的速率是较低温度（1.5 - 3摄氏度）下的速率的3 - 4倍。在存在Mg 2+离子（1.5 mM）和β，γ-亚甲基ATP（1 mM）的情况下，温度对速率的影响在含Ca 2+的培养基中消失，但在无Ca 2+的培养基中仍然存在。6.当将咖啡因（1.2 mM）（Ca 2+诱导的Ca 2+释放的增强剂）加入到含有Mg 2+和β，γ-亚甲基ATP的试验培养基中时，所产生的增强效果是低温下的数倍。7.为了检查SR的Ca 2+泵活性的温度依赖性，在Mg 2+离子（1.5mM）和Mg-ATP（3.5mM）存在下，在各种条件下测定空SR的Ca 2+摄取的初始速率。在检查的Ca 2+离子浓度（小于10（-6）M）下，泵活性的Q10约为2.0。8.根据所获得的结果，加上一些合理的假设，一个数值模型表明，这两个抑制的Ca 2+泵和增强的Ca 2+释放有助于冷却收缩的咖啡因化的纤维。
1. In order to clarify the mechanism of contracture on cooling of caffeine‐treated intact muscle fibres, the temperature dependence of a calcium (Ca2+) release mechanism, 'Ca2+‐induced Ca2+ release', of the sarcoplasmic reticulum (SR) was examined in skinned frog muscle fibres. 2. Skinned fibres in a solution containing 1.2 mM‐caffeine and 0.7 mM‐EGTA (Mg2+, 1.5 mM, Mg‐ATP, 3.5 mM, pH 7), contracted on cooling (from 22 to 2 degrees C) due to Ca2+ release from the SR. 3. The rate of Ca2+ release from skinned fibre SR in a medium which contained Ca2+ ions (with 10 mM‐EGTA) and no ATP salts, was determined under various conditions using the 'caffeine method.' 4. In the absence of Mg2+ ions, adenine nucleotides and caffeine, the rates at room temperature (21‐22 degrees C) were 3‐4 times greater than those at a lower temperature (1.5‐3 degrees C), at any concentrations of Ca2+ ions external to the SR. 5. In the presence of Mg2+ ions (1.5 mM) and beta,gamma‐methylene ATP (1 mM), the effect of temperature on the rates disappeared in Ca2+‐containing media, although the effect remained in Ca2+‐free medium. 6. When caffeine (1.2 mM), which is a potentiator of the Ca2+‐induced Ca2+ release, was added to the test medium with Mg2+ and beta,gamma‐methylene ATP, the resulting potentiating effect was several times greater than that at lower temperature. 7. In order to examine the temperature dependence of the Ca2+ pump activity of the SR, the initial rate of Ca2+ uptake by the empty SR was determined under various conditions in the presence of Mg2+ ions (1.5 mM) and Mg‐ATP (3.5 mM). The Q10 of the pump activity was around 2.0 at the Ca2+ ion concentrations examined (less than 10(‐6) M). 8. A numerical model based on the results obtained, together with some reasonable assumptions, suggested that both suppression of the Ca2+ pump and enhancement of the Ca2+ release contribute to the cooling contracture of caffeinized fibres.
影响因子：
5.5
作者：
BAYLOR, SM;CHANDLER, WK;MARSHALL, MW
通讯作者：
MARSHALL, MW