The effect of body warming on the ventilatory response to CO2 in the awake dog

Resting awake dogs breathing CO2 lower body temperature and such a change is reported to decrease the ventilatory response to CO2. Therefore, in 6 awake dogs the ventilatory response to CO2, obtained while body temperature was allowed to decrease spontaneously, was compared to the response obtained during warming of their body surface in an attempt to prevent the fall in temperature during hypercapnia. During warming, rectal temperature was maintained 0.5 to 0.7 degrees C higher than when TR was allowed to fall. In warm studies arterial [HCO-3]a was decreased relative to PaCO2 whereas there was a surprisingly large storage of CO2, 17.3 ml CO2/kg . Torr PaCO2. Ventilation was comparable in the dogs during air control of both experiments and before body warming was initiated. Subsequently, there was no consistent effect of warming on either the slope or threshold of the ventilatory response to CO2 with respect to either PaCO2 or pHa. Therefore, producing a higher and more 'normothermic' TR during hypercapnia in awake dogs had no definitive effect on chemical control of breathing.