Relative contribution of central and peripheral chemoreceptors to the ventilatory response to CO2 during hyperoxia

Using the technique of artificial ponto-medullary perfusion, the steady state ventilation during hyperoxia was measured in 15 anaesthetized cats as a function of the central PaCO2 (PaCO2) and peripheral PaCO2 (PapCO2). To a first approximation the ventilatory response was linearly related to both the central and peripheral arterial carbon dioxide pressures, viz. VE=SC . PacCO2 + Sp . PapCO2 - K where Sc and Sp represent the overall central and peripheral sensitivity to carbon dioxide. The mean ratio Sp/Sc was 0.48 (range 0.21 to 1.08). In carotid sinus denervated cats Sp was zero, while the values of Sc in these cats were in the range of Sc of cats with intact carotid sinus nerves. It is concluded that the peripse to CO2 under steady-state conditions. Chemodenervation experiments revealed that the carotid bodies play an essential role in this contribution.