Changing O₂ availability dictates sensitivity to ZnCl₂.

<p><b>A</b>&<b>B</b>: Left panels show representative traces of ouabain-SD generated under different oxygen concentrations and right panels show summary effects on propagation rate and SD onset. ZnCl₂ (100 µM) application produced a significant decrease in SD propagation rate in 21% O₂, but inhibitory effects of Zn²⁺ were not observed in in 0% O₂ (n=6 each, **p<0.01). <b>C</b>. Reduction of field excitatory postsynaptic potentials (fEPSP) during hypoxia. Baseline recordings were in 95% O₂, before exchange with either 21% or 0% O₂ (replaced with N₂, see Methods). * p<0.05, n=5 each. <b>D</b>. Suppression of synaptic transmission with the A1 receptor agonist CPA (300 nM, in 95% O₂) decreased SD propagation rate, but did not prevent inhibition by ZnCl₂ (n=5, **p<0.01) Experiments were performed on slices obtained from male FVB/N mice.