Acetylcholine receptors. Distribution and extrajunctional density in rat diaphragm after denervation correlated with acetylcholine sensitivity.
Acetylcholine receptors. Distribution and extrajunctional density in rat diaphragm after denervation correlated with acetylcholine sensitivity.
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DOI：
10.1085/jgp.60.3.248
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发表时间：
1972-09
期刊：
影响因子：
--
通讯作者：
Fambrough DM
中科院分区：
文献类型：
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作者：
Hartzell HC;Fambrough DM
用~(125)I标记的α-银环蛇毒素(α-BGT-125I)和定量放射自显影技术，研究了去神经支配后大鼠膈肌内乙酰胆碱(ACh)受体分布和密度变化的时程。在有神经支配的纤维中，ACh受体定位于神经肌肉交界处，连接外受体密度小于每平方微米5个受体。结外受体密度在失神经支配后2~3天开始增加，14天接近线性增加至1695个/微米~2，45天下降至529个/微米~2。我们分离了去神经支配后不同时间大鼠腿肌的质膜，发现用α-BGT-125I结合和闪烁计数法测得的膜上ACh受体浓度的变化与放射自显影测得的ACh受体密度的变化具有相似的时程。此外，我们还将放射自显影测定的ACh受体密度与电泳法和细胞内记录测定的ACh敏感性进行了相关，发现ACh受体密度的对数是ACh敏感性对数的0.53倍。这些结果从ACh受体的电生理实验和最近更多的生化方法来研究ACh受体的控制和功能方面进行了讨论。
Using 125iodine-labeled α-bungarotoxin (α-BGT-125I) and quantitative radioautography, we have studied the time-course of the change in acetylcholine (ACh) receptor distribution and density occurring in rat diaphragm after denervation. In innervated fibers, ACh receptors are localized at the neuromuscular junction and the extrajunctional receptor density is less than five receptors per square micrometer. The extrajunctional receptor density begins to increase between 2 and 3 days after denervation and increases approximately linearly to 1695 receptors/µm2 at 14 days, subsequently decreasing to 529 receptors/µm2 at 45 days. We have isolated plasma membranes from rat leg muscles at various times after denervation and find that the change in concentration of ACh receptors in the membranes measured by α-BGT-125I binding and scintillation counting follows a time-course similar to the change in ACh receptor density measured radioautographically. Furthermore, we have correlated extrajunctional ACh receptor density measured by radioautography with extrajunctional ACh sensitivity measured by iontophoretic application of ACh and intracellular recording and find that the log of ACh receptor density is related to 0.53 times the log of ACh sensitivity. These results are discussed in terms of the electrophysiological experiments on the ACh receptor and the recent, more biochemical approaches to the study of ACh receptor control and function.