CHEMICAL CONTROL OF BREATHING IN THE LIZARD, VARANUS-EXANTHEMATICUS

1. 1. In Varanus exanthematicus, alterations of inspired and end-tidal gas pressures resulted in rapid ventilatory responses. This, as well as other physiological characteristics, contributes to a homeostatic ability unusual for a reptile. 2. 2. In contrast to the lizard Lacerta, the varanid showed a positive ventilatory response to hypoxia. 3. 3. Whereas CO2 breathing depressed breathing frequency in other lizards, both tidal volume and frequency increased in Varanus. 4. 4. End-tidal Pco2 increased significantly after feeding, presumably compensating for an alkaline tide" of digestion. The increased end-tidal Pco2 not due to a decrease in ventilation. © 1979."