Fig. 8.

P2X₄ channels expressed in embryonic hippocampal neurons. A, B, Bright-field (A) and fluorescence (B) image of embryonic hippocampal neurons transfected with plasmids for P2X₄ and EGFP. Note that the morphology of transfected and nontransected neurons is very similar, and this appearance is typical of healthy cells. The extended fluorescent cells in Bare glial cells. C, Top trace,Representative voltage-clamp currents recorded from an untransfected neuron showing no ATP-evoked currents (holding potential, −60 mV);bottom trace, large ATP-evoked currents in a transfected hippocampal neuron. D, Top trace,Representative current-clamp recording (resting potential, −52 mV) from an untransfected neuron showing no ATP-evoked change in membrane potential; bottom trace, large ATP-evoked depolarization in a transfected hippocampal neuron. Action potentials have been clipped. E, Representative traces from a transfected hippocampal neuron showing 10 μm ATP-evoked currents before and after 3 μm IVM application. F, Summary of experiments such as those illustrated in Efrom six neurons. Note that the size of the ATP-evoked current varies markedly between neurons, but in all neurons IVM potentiates the current.