The frequency of spontaneous IPSCs also increases during hypoxia. A, Voltage-clamp traces obtained with a Cs gluconate-containing pipette from a representative layer 5 neuron held at 0 mV under normoxic conditions. B, Thirty seconds after the onset of hypoxia, the frequency of sIPSCs increases; high-amplitude events are seen frequently. C, At the third minute of hypoxia, the high-amplitude sIPSCs disappear; the frequency of the rest of the spontaneous events additionally increases.D, Reoxygenation rapidly decreases the frequency of sIPSCs.