RESPIRATORY CONTROL IN BULLFROGS - CUTANEOUS VERSUS PULMONARY RESPONSE TO SELECTIVE CO2 EXPOSURE

Bullfrogs, Rana catesbeiana, were exposed to high ambient PCo2 (15–22 Torr) at 20°C through either their skin or their lungs. The objective was to evaluate the effectiveness of the gas exchange surface not exposed to high CO2 to excrete the excess CO2 load. Frogs exposed to high CO2 through their skin increased pulmonary ventilation and controlled arterial PCO2, close to the normal value. In contrast, frogs that breathed CO2 did not increase their skin CO2 conductance, and arterial PCO2, increased significantly. These results support the concept that the lungs are the primary effector mechanism for respiratory control in the bullforg while the skin is a passive, poorly controlled avenue for CO2 loss. They also reveal that the lungs of this anuran are affective eliminators of CO2. © 1979, Springer-Verlag. All rights reserved.