The Effect of Intravenous Infusion of Lactic Acid on Carotid Chemoreceptor Discharge in Anaesthetized Cats Ventilated with Room Air or 100% O₂

Abstract

It has been suggested that the responses of the peripheral arterial chemoreceptors to physiological stimuli are effectively abolished at high P_aO₂ (Cunningham 1987; Dejours 1962; Ward & Bellville 1983). Consequently, inspiration of hyperoxic gas mixtures has been widely used to silence the peripheral chemoreceptors in order to assess their contribution to the control of ventilation (e.g. Conway & Petersen 1987; Holtby et al., 1988; Rausch et al., 1991). More recently, Dahan et al. (1990) have suggested that 100% O₂ does not silence the peripheral chemoreceptor response to increases in P_aCO₂ in man. Furthermore, Kozlowski et al. (1971) reported that lesser degrees of hyperoxia do not abolish peripheral chemoreceptor drives. These findings call into question the hypothesis that hyperoxia abolishes the peripheral arterial chemoreceptor responses to physiological stimuli. In particular, the response of these receptors to metabolic acidosis, such as occurs during heavy exercise, may not be silenced.