Inhibition of ATP-activated current by zinc in dorsal root ganglion neurones of bullfrog
Inhibition of ATP-activated current by zinc in dorsal root ganglion neurones of bullfrog
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DOI：
10.1111/j.1469-7793.1997.641ba.x
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发表时间：
1997-12-15
影响因子：
5.5
通讯作者：
Weight, FF
中科院分区：
文献类型：
--
作者：
Li, CY;Peoples, RW;Weight, FF
1.采用全细胞膜片钳技术研究了Zn 2+对牛蛙背根神经节（DRG）神经元ATP激活电流的影响. Zn ~（2+）（2-800 μ M）可抑制次最大浓度ATP激活的电流。对2.5 μ M ATP激活的电流产生50%抑制（IC 50）的Zn 2+浓度为61 +/- 9.8 μ M。当调整ATP浓度以解释Zn 2+的螯合作用时，Zn 2+的IC 50为86 +/-18 μ M。Zn 2+对ATP门控通道的抑制作用似乎不是由于一种或多种ATP的浓度降低。Zn 2+对ATP激活电流的抑制不依赖于膜电位在-80 ~+40 mV之间的变化，也不涉及电流反转电位的移动. Zn 2+（100 μ M）以平行方式使ATP浓度-反应曲线向右移动，使ATP的EC 50从2.5 +/- 0.5 μ M增加到5.5 +/- 0.4 μ M。Zn 2+降低ATP门控离子通道的失活时间常数，而不影响激活或脱敏时间常数.二硫苏糖醇（DTT）可逆转Zn 2+对ATP激活电流的抑制. 2-甲硫基ATP、α，β-亚甲基ATP和ADP激活电流，EC 50值分别为2.4 +/- 0.3、50 +/- + 5.8和303.1 +/- 53.9 μ M。腺苷、AMP或β、γ-亚甲基ATP未引起可检测的电流。活性蓝2和磷酸吡哆醛-6-偶氮苯基-2 '，4'-二磺酸抑制ATP激活电流。结果表明，Zn ~（2+）可通过降低P2 X嘌呤受体与ATP结合位点的亲和力而抑制P2 X嘌呤受体的功能。这些观察结果为Zn 2+对神经递质门控离子通道的这种作用提供了第一个证据。此外，这些神经元中的受体通道似乎是P2 X嘌呤受体类的新成员。
1. The effect of Zn2+ on ATP-activated current was studied in bullfrog dorsal root ganglion (DRG) neurones using the whole-cell patch-clamp technique.2. Zn2+ (2-800 mu M) inhibited current activated by submaximal concentrations of ATP. The Zn2+ concentration that produced 50 % inhibition (IC50) of current activated by 2.5 mu M ATP was 61 +/- 9.8 mu M. When ATP concentrations were adjusted to account for chelation of Zn2+ the IC50 of Zn2+ was 86 +/- 18 mu M.3. The inhibitory action of Zn2+ on ATP-gated channels did not appear to be due to a decrease in the concentration of one or more species of ATP.4. Zn2+ inhibition of ATP-activated current was independent of membrane potential between -80 and +40 mV, and did not involve a shift in the reversal potential of the current.5. Zn2+ (100 mu M) shifted the ATP concentration-response curve to the right in a parallel manner, increasing the EC50 for ATP from 2.5 +/- 0.5 mu M to 5.5 +/- 0.4 mu M.6. Zn2+ decreased the time constant of deactivation of ATP-gated ion channels without affecting the time constant of activation or desensitization.7. Dithiothreitol (DTT) reversed Zn2+ inhibition of ATP-activated current.8. 2-Methylthio ATP, alpha,beta-methylene ATP and ADP activated current with EC50 values of 2.4 +/- 0.3, 50 +/- + 5.8 and 303.1 +/- 53.9 mu M, respectively. Adenosine, AMP or beta,gamma-methylene ATP did not evoke detectable current.9. Reactive Blue 2 and pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid inhibited ATP-activated current.10. The results suggest that Zn2+ can inhibit P2X purinoceptor function by decreasing the affinity of the binding site for ATP. These observations provide the first evidence for this action of Zn2+ on a neurotransmitter-gated ion channel. Furthermore, the receptor-channel in these neurones appears to be a novel member of the P2X purinoceptor class.