Figure 2.

Diving procedure. Following the insertion of the probes into the brains, the rats were allowed a recovery time of 2 hours and 40 minutes before the four blank microdialysates were collected to establish the baseline. Each square represents one dialysate sample collected every twenty minutes. The stimulation by retrodialysis and the compression stage (or simili under atmospheric pressure) began at the same time. Rats remained at the maximal compression (or simili) for 3 hours. The dotted line marks the pressure of the inert gas and the oxygen partial pressure.