POTASSIUM EFFLUX FROM SINGLE SKINNED SKELETAL-MUSCLE FIBERS
POTASSIUM EFFLUX FROM SINGLE SKINNED SKELETAL-MUSCLE FIBERS
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DOI：
10.1016/s0006-3495(85)83853-4
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发表时间：
1985-12-01
影响因子：
3.4
通讯作者：
ABRAMCHECK, CW
中科院分区：
文献类型：
--
作者：
BEST, PM;ABRAMCHECK, CW
已经确定了42K从单个剥皮（去除了肌膜）的骨骼肌纤维中流出。同位素冲蚀曲线在动力学上是复杂的，可以用三个指数的总和来拟合，其中包括一个快分量（k = 0.25 s-1），其池大小相当于光纤体积的91%，一个中间分量（k = 0.08 s-1）相当于光纤体积的6%，一个慢分量（k = 0.08 s-1）相当于光纤体积的0.5%。洗涤剂对纤维的预处理只有中间动力学组分有显著影响。洗涤剂处理过的纤维的流出曲线可以像两个指数的和一样拟合，其系数和速率常数可与未经处理的对照水洗的快、慢分量的系数和速率常数相当。类似地，[14C]蔗糖的冲洗可以被描述为两个指数的和。我们得出结论，42K冲刷的中间成分是由离子从蒙皮纤维内的膜结合空间运动引起的。由于其相对体积，肌浆网似乎是一个合理的选择，作为一个结构相关的这一组成部分。我们根据流出数据估计肌浆网（SR）的钾透性为10-7 cm/s。这一数值低于以前对孤立制剂的估计。
The efflux of 42K from single, skinned (sarcolemma removed) skeletal muscle fibers has been determined. Isotope washout curves are kinetically complex and can be fit as the sum of three exponentials, including a fast component (k = 0.25 s-1) with a pool size equivalent to 91% of the fiber volume, an intermediate component (k = 0.08 s-1) equivalent to 6% of the fiber volume, and a slow component (k = 0.08 s-1) equivalent to 0.5% of fiber volume. Only the intermediate kinetic component is significantly affected by pretreatment of fibers with detergent. Efflux curves from detergent-treated fibers could be as fit as the sum of two exponentials with coefficients and rate constants comparable to those of the fast and slow component of washout of untreated controls. Similarly the washout of [14C]sucrose can be described as the sum of two exponentials. We conclude that the intermediate component of 42K washout results from the movement of ions from a membrane bound space within the skinned fiber. Because of its relative volume, the sarcoplasmic reticulum seems to be a reasonable choice as a structural correlate with this component. Our estimate of the potassium permeability for the sarcoplasmic reticulum (SR) based on the efflux data is 10-7 cm/s. This value is less than previous estimates from isolated preparations.