Figure 5.

Pervanadate inhibits human α7 nAChRs in Xenopus oocytes. a, ACh-evoked (1 mm, 3 s) current without (left) or after 0.5-1 h incubation with 50 μm pervanadate (perv, right). b, ACh dose-response curve without (squares, dashedline; n = 28) and after pervanadate treatment (crosses, solid line; n = 22). Currents were evoked by successive test pulses (3 s) with increasing ACh concentrations, applied every 90 s. Currents were normalized to 1 at saturating ACh concentration (no perv). Data points are expressed as mean ± SEM, and the lines correspond to the best fit with a Hill equation (supplemental Table 1, available at www.jneurosci.org as supplemental material). Significant differences between pervanadate and control treatments were calculated by unpaired, two-tailed Student's t tests (^*p < 0.01). c, SH-α7 cells were treated for 90 min with 10 μm CGP77675, followed by addition of 50 μm pervanadate. In controls, these compounds were omitted or an excess of free α-BT was added before precipitation (+T). Intracellular or surface α7 receptors were precipitated using biotinylated α-BT and analyzed by phosphotyrosine and α7 immunoblotting. Pervanadate causes phosphorylation of surface but not internal α7 receptors, and this phosphorylation originates from SFKs. Pervanadate, alone or with CGP77675, does not decrease the number of surface α7 receptors or affect internal α7. d, α7 blots as shown in c were quantitated by densitometric scanning (mean ± SD; n = 10).