Effect of tetanus duration on the free calcium during the relaxation of frog skeletal muscle fibres.
Effect of tetanus duration on the free calcium during the relaxation of frog skeletal muscle fibres.
复制标题
破伤风持续时间对青蛙骨骼肌纤维松弛过程中游离钙的影响。
DOI：
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
M. Cannell
中科院分区：
文献类型：
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作者：
M. Cannell
从青蛙的胫骨前肌中分离出单纤维，并注射光蛋白水母发光蛋白。张力和光发射的注射水母发光蛋白（细胞内游离钙浓度的函数）记录在休息和破伤风放松期间。来自静息单纤维的光发射水平对应于100 nM（+/-40 nM，n = 4）的游离细胞内钙浓度（[Ca 2 +]i）。在肌肉放松的三个阶段期间检查光的下降的时间过程：在张力放松的缓慢阶段期间1，在放松的指数阶段期间2和在力放松完成后的期间3。光下降的时间过程（在水母发光蛋白反应动力学校正之后）显示，在10 ℃下的单次刺激之后，[Ca 2 +]i以25 s-1（+/-1.7，n = 3）的速率常数呈指数下降。随着破伤风持续时间的增加，[Ca 2 +]i的下降率在第1阶段下降。有人建议，这种下降率的下降[Ca 2 +]i的结果从细胞内钙缓冲液（它采取了钙与肌浆网平行）变得加载钙在破伤风。在整个阶段2 [Ca 2 +]i升高高于静息水平。在此期间的[Ca 2 +]i的水平变化从纤维到纤维，但可以高达1 μ M。[Ca ~（2+）]i的平均水平在此期间也依赖于破伤风持续时间。在第3阶段观察到[Ca 2 +]i的长期升高，[Ca 2 +]i以近似指数的时间过程恢复至静息水平。在此期间，[Ca 2 +]i的水平（在最后一次刺激后的给定时间）取决于破伤风持续时间。这表明[Ca 2 +]i的这种长期升高反映了上述细胞内钙缓冲液中钙的释放。结果表明，[Ca 2 +]i的下降率在几秒钟的强直刺激后，可以解释由肌浆网的钙螯合率。在较短时间的刺激后，[Ca 2 +]i的下降速率增加可以解释为存在与肌浆网平行吸收钙的缓冲液。在第3阶段，钙从缓冲液中的后期释放导致[Ca 2 +]i的长期升高。这种缓冲液的钙结合和释放的缓慢动力学似乎与已发表的小清蛋白动力学性质的数据相兼容。
Single fibres were dissected from the tibialis anterior muscle of the frog and injected with the photoprotein aequorin. Tension and the light emission of the injected aequorin (a function of the free intracellular calcium concentration) were recorded both at rest and during tetanus relaxation. The level of light emission from resting single fibres corresponded to a free intracellular calcium concentration ([Ca2+]i) of 100 nM (+/‐ 40 nM, n = 4). The time course of the decline in light was examined during the three periods of muscle relaxation: period 1 during the slow phase of tension relaxation, period 2 during the exponential phase of relaxation and period 3 after the completion of force relaxation. The time course of the decline in light (after a correction for the kinetics of the aequorin reaction) showed that [Ca2+]i declines exponentially with a rate constant of 25 s‐1 (+/‐ 1.7, n = 3) after a single stimulus at 10 degrees C. With increasing tetanus duration, the rate of decline of [Ca2+]i decreased during period 1. It is suggested that this decrease in the rate of decline of [Ca2+]i results from an intracellular calcium buffer (which takes up calcium in parallel with the sarcoplasmic reticulum) becoming loaded with calcium during the tetanus. Throughout period 2 [Ca2+]i was elevated above resting levels. The level of [Ca2+]i during this period varied from fibre to fibre but could be as high as 1 microM. The mean level of [Ca2+]i during this period also depended on the tetanus duration. A long‐lasting elevation in [Ca2+]i was observed during period 3, [Ca2+]i returning towards resting levels with an approximately exponential time course. During this period the level of [Ca2+]i (at a given time after the last stimulus) depended on the tetanus duration. It is suggested that this long‐lasting elevation in [Ca2+]i reflects the release of calcium from the intracellular calcium buffer described above. The results suggest that the rate of decline of [Ca2+]i after a few seconds of tetanic stimulation can be explained by the rate of calcium sequestration by the sarcoplasmic reticulum. The increased rate of decline of [Ca2+]i after shorter periods of stimulation may be explained by the presence of a buffer that takes up calcium in parallel with the sarcoplasmic reticulum. The later release of calcium from this buffer gives rise to the long‐lasting elevation in [Ca2+]i during period 3. The slow kinetics of calcium binding and release by this buffer appear compatible with published data on the kinetic properties of parvalbumin.
影响因子：
5.5
作者：
BAYLOR, SM;CHANDLER, WK;MARSHALL, MW
通讯作者：
MARSHALL, MW
电子探针 X 射线微量分析强直后 Ca2 和 Mg2 在原位肌浆网的运动。
DOI：
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发表时间：
1985
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Somlyo,AV;McClellan,G;Gonzalez-Serratos,H;Somlyo,AP
通讯作者：
Somlyo,AP
影响因子：
5.5
作者：
ALLEN, DG;KURIHARA, S
通讯作者：
KURIHARA, S