Calcium signals recorded from cut frog twitch fibers containing tetramethylmurexide.
Calcium signals recorded from cut frog twitch fibers containing tetramethylmurexide.
复制标题
钙信号从含有四甲基氧化物的切割的青蛙抽搐纤维记录。
DOI：
10.1085/jgp.89.1.145
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发表时间：
1987-01
影响因子：
3.8
通讯作者：
Chandler, W K
中科院分区：
文献类型：
--
作者：
Maylie, J;Irving, M;Sizto, N L;Boyarsky, G;Chandler, W K
通过从末端池溶液中扩散，将钙指示剂四甲基紫脲酸酯引入切割纤维中，安装在双凡士林缝隙小室中。指示剂迅速扩散到光纤的中心区域，在那里进行光学记录，如果移除，扩散速度也同样快。浓度的时间历程表明，平均而言，0.27份指示剂可逆地与肌浆组分结合，18℃时的自由扩散常数为1.75×10(-6)cm~2/S。静态吸收光谱的形状表明，纤维中0.11-0.15份的四甲基紫脲酸与钙形成络合。在动作电位刺激后，指示性吸光度有一个快速的瞬时变化，然后是一个维持的相反的符号的变化。这两种变化的波长依赖性符合试管钙差谱。早期峰的幅度随指示剂浓度线性变化，对应的游离钙平均升高17微米。如果肌浆网膜对无钙指示剂具有通透性，则可以解释这些不同的发现。扩散分析显示肌浆网内的无钙指示剂和钙络合指示剂均被结合，而钙络合指示剂可通过静息吸收光谱检测到。指示剂吸光度的瞬时变化将由肌浆钙与在肌浆溶液中自由扩散的指示剂分子反应而产生。保持的信号，报告钙从静息状态下复杂的指示剂解离，将来自肌浆网内的变化。基于这些思想，描述了一种用于分离四甲基紫脲酸酯信号的两个分量的方法。在18℃时，估计的肌浆游离[Ca]瞬变的平均峰值为26微米。它的时间进程与安替比拉佐III(Maylie，J.，M.Irving，N.L.Sizto和W.K.Chandler)记录的时间相似，但可能更快。1987年。普通生理学杂志。89：83-143)。
The Ca indicator tetramethylmurexide was introduced into cut fibers, mounted in a double-Vaseline-gap chamber, by diffusion from the end- pool solutions. The indicator diffused rapidly to the central region of a fiber where optical recording was done and, if removed, diffused away equally fast. The time course of concentration suggests that, on average, a fraction 0.27 of indicator was reversibly bound to myoplasmic constituents and the free diffusion constant was 1.75 x 10(- 6) cm2/s at 18 degrees C. The shape of the resting absorbance spectrum suggests that a fraction 0.11-0.15 of tetramethylmurexide inside a fiber was complexed with Ca. After action potential stimulation, there was a rapid transient change in indicator absorbance followed by a maintained change of opposite sign. The wavelength dependence of both changes matched a cuvette Ca-difference spectrum. The amplitude of the early peak varied linearly with indicator concentration and corresponded to an average rise in free [Ca] of 17 microM. These rather diverse findings can be explained if the sarcoplasmic reticulum membranes are permeable to Ca-free indicator. Both Ca-free and Ca- complexed indicator inside the sarcoplasmic reticulum would appear to be bound by diffusion analysis and the Ca-complexed form would be detected by the resting absorbance spectrum. The transient change in indicator absorbance would be produced by myoplasmic Ca reacting with indicator molecules that freely diffuse in myoplasmic solution. The maintained signal, which reports Ca dissociating from indicator complexed at rest, would come from changes within the sarcoplasmic reticulum. A method, based on these ideas, is described for separating the two components of the tetramethylmurexide signal. The estimated myoplasmic free [Ca] transient has an average peak value of 26 microM at 18 degrees C. Its time course is similar to, but possibly faster than, that recorded with antipyrylazo III (Maylie, J., M. Irving, N. L. Sizto, and W. K. Chandler. 1987. Journal of General Physiology. 89:83- 143).