Stoop R, Surprenant A, North R A
Geneva Biomedical Research Institute, Glaxo Wellcome Research and Development, Plan-les-Ouates, 1228 Geneva, Switzerland.
J Neurophysiol. 1997 Oct;78(4):1837-40. doi: 10.1152/jn.1997.78.4.1837.
The effect of changing extracellular pH was studied on the currents induced by ATP or alphabeta-methylene-ATP in HEK293 cells transfected with different P2X receptor subunits. In cells expressing P2X1, P2X3, or P2X4 receptors, the effect of ATP was decreased by acidification. In cells expressing P2X2 receptors, acidification increased the ATP-induced current; this effect was also seen in cells expressing heteromeric P2X2 and P2X3 receptors. At P2X2 receptors, acidification caused a leftward shift in the ATP concentration-response curve, without change in maximum; the pKa for this effect was 7.3. At P2X4 receptors, acidification caused a rightward shift in the ATP concentration-response curve, without change in the maximum; the pKa for this effect was 6.8. The pH dependence of the action of ATP should be taken into account in studies of synaptic transmission, and it may provide a further tool to assign molecular identity to P2X receptors expressed by brain neurons.
研究了细胞外pH变化对转染了不同P2X受体亚基的HEK293细胞中ATP或αβ-亚甲基-ATP诱导电流的影响。在表达P2X1、P2X3或P2X4受体的细胞中，酸化会降低ATP的作用。在表达P2X2受体的细胞中，酸化会增加ATP诱导的电流；在表达异源P2X2和P2X3受体的细胞中也观察到了这种效应。在P2X2受体处，酸化导致ATP浓度-反应曲线向左移动，最大值不变；这种效应的pKa为7.3。在P2X4受体处，酸化导致ATP浓度-反应曲线向右移动，最大值不变；这种效应的pKa为6.8。在突触传递研究中应考虑ATP作用的pH依赖性，它可能为确定脑神经元表达的P2X受体的分子身份提供进一步的工具。
