The highest ambient temperature tolerated by normocapnic and hypercapnic rabbits.

The highest ambient temperature tolerated by rabbits was 30 degrees C at the relative humidity of air 80-95%. During the exposure to these environmental conditions the vasomotor thermoregulatory response developed fully, while the respiratory frequency did not attain the maximum level, i.e. the rabbit's potential ability for thermal panting. Prolonged heat exposure (approx. 4 hours) had a depressive effect on the respiratory frequency. Increased concentration of carbon dioxide (3, 6 and 9%) in the inspired gas mixture did not disturb the thermoregulatory mechanisms at 30 degrees C in the rabbits.