Effect of temperature on the CO₂ sensitivity of avian intrapulmonary chemoreceptors

We determined linear regressions of discharge frequency on In P_CO2 of 23 intrapulmonary chemoreceptors (IPC) from eight hyperthermic, adult cockerels. At low P_CO2, IPC in hyperthermic cockerels discharged slower than IPC measured in euthermic cockerels; above 25 torr P_Co2, however, they discharged faster than euthermic IPC. Thus, IPC were less sensitive to P_CO2 during hyperthermia. We calculate that a 1°C increase in the temperature of the lung (TL) causes the slope of the linear regression of discharge frequency on In P_CO2 to be less negative by 1.5 ± 0.5 imp (sec·In P_CO2)^-1 and that, for any increase in TL above normal (41.5°C), the average IPC discharge frequency equals (-10.7+1.5 (TL-41.5)). (In ( P_CO2 25.0)) + 3.7. This relationship may be partly responsible for the increased tidal volume and decreased respiratory frequency observed when body temperature increases during constant Pa_CO2.