Fig. 7.

Zn²⁺ potentiation of α4β4 receptors and inhibition of α3β2 receptors are voltage independent.A, Current responses of an α4β4-expressing oocyte to 1 μm ACh before, during, and after coapplication of 50 μm Zn²⁺ at membrane holding potentials of −40 mV (left trace, calibration: 50 nA, 20 sec) and −90 mV (right trace, calibration: 200 nA, 20 sec). The traces were normalized for comparison. B, Current responses of α4β4-expressing oocytes to 1 μm ACh in the presence of 50 μm Zn²⁺ were recorded at various holding potentials and plotted as a percentage of the response to ACh alone (mean ± SEM of 3 oocytes). Current responses of α3β2 expressing oocytes to 4 μm ACh in the presence of 100 μm Zn²⁺ were recorded at various holding potentials and plotted as a percentage of the response to ACh alone (mean ± SEM of 3 oocytes).