Recovery from hypobaric hypoxia in the rabbit

In rabbits, recovery was studied from hypobaric hypoxia elicited by decompression to 190 mm Hg. In the first experiment a pattern discrimination habit was used. A marked latency appeared after hypoxia, before the rabbits started to respond, but once started no difference was found compared to control circumstances. Repeating this procedure 48 h later resulted in a spontaneous decrease in latency, which remained significantly longer than without hypoxia. In the second experiment rabbits were on a time-restricted daily drinking schedule and the water drinking behaviour was registered. Due to the preceding hypoxia the rate of drinking was much lower compared with the control animals, as was the average total fluid intake. After 48 h the impact of hypoxia was much less. In the third experiment the influences of repeated periods of hypoxia upon the heart rate were studied. Rabbits showed a marked bradycardia during hypoxia which was less severe 48 h later. It was argued that studying recovery from hypoxia is potentially valuable to gain information about the effects of cerebral hypoxia and the autonomic responses that influence the final outcome of hypoxic stress in the intact rabbit.