RECEPTOR CURRENT FLUCTUATION ANALYSIS IN THE LABELLAR SUGAR RECEPTOR OF THE FLESHFLY
RECEPTOR CURRENT FLUCTUATION ANALYSIS IN THE LABELLAR SUGAR RECEPTOR OF THE FLESHFLY
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DOI：
10.1085/jgp.91.1.29
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发表时间：
1988-01-01
影响因子：
3.8
通讯作者：
MORITA, H
中科院分区：
文献类型：
--
作者：
KIJIMA, H;NAGATA, K;MORITA, H
分析了肉蝇标签糖受体受体电流的波动。受体电流在细胞外记录为味觉感受器尖端和基部之间的电位下降。经过河豚毒素处理后，味觉细胞完全失去了冲动，但保留了受体电流，从而有利于受体电流的分析，而不受冲动的干扰。当感器受到有效糖（麦芽糖、蔗糖和果糖）刺激时，电流波动显着增加。波动随着受体电流的发展而增加，这表明一旦糖到达感觉过程的顶点，波动就会发生。通过计算自相关函数（ACF）或功率谱（PS）对波动进行分析表明：（a）波动与糖浓度曲线的方差（均方）达到最大值，与受体电流显示的单调增加相反； (b) ACF 通过指数项近似，其时间常数根据所用糖及其浓度而不同。果糖和麦芽糖的时间常数随着糖浓度的增加而减小。在引起相同大小的受体电流的糖浓度下，果糖的时间常数最大，麦芽糖的时间常数最小。强烈建议转导离子通道存在于糖受体细胞感觉过程的尖端区域，并直接由糖操作。
Fluctuations in the receptor current of the labellar sugar receptor of the fleshfly were analyzed. The receptor current was recorded extracellularly as a drop in potential between the tip and the base of the taste sensillum. After treatment with tetrodotoxin, the taste cells completely lost their impulses but retained their receptor currents, thus facilitating analysis of the receptor current without disturbance by impulses. The current fluctuation increased markedly when the sensillum was stimulated with effective sugars: maltose, sucrose, and fructose. The fluctuation increased in parallel with development of the receptor current, which indicates that it occurs as soon as the sugar reaches the apex of the sensory process. Analysis of fluctuations by computation of autocorrelation functions (ACFs) or power spectra (PS) revealed that: (a) the variance (mean square) of fluctuation vs. sugar concentration curve reached a maximum, in contrast to the monotonic increase shown by the receptor current; (b) the ACF was approximated by an exponential term, and its time constant differed according to the sugars used and their concentrations. The time constants for fructose and maltose decreased with increases in sugar concentration. At the concentrations of sugars evoking the same magnitude of receptor current, the time constant for fructose was the largest and that for maltose was the smallest. It was strongly suggested that transduction ion channels are present at the tip region of the sensory process of the sugar receptor cell and are operated directly by sugars.