EFFECTS OF POTASSIUM AND LACTIC-ACID ON CHEMORECEPTOR DISCHARGE IN ANESTHETIZED CATS

Both increasing [K+]a and falling pHa stimulate ventilation through an action on the peripheral chemoreceptors. We have examined the effect on afferent carotid chemoreceptor discharge, of intravenous infusion o f lactic acid alone, KCl alone, and both combined at constant PET(CO2) in anaesthetized, artificially ventilated cats. Infusions of lactic a cid alone and KCl alone caused similar increases in both the mean and amplitude of oscillation of chemoreceptor discharge. In the case of th e lactic acid alone infusion the increase in the amplitude of oscillat ion could be accounted for by the resultant increase in carbon dioxide production. Simultaneous infusion of KCl and lactic acid caused an in crease in the mean and amplitude of the discharge which was greater th an either given alone, although the combined effect was less than addi tive. The alterations in mean and amplitude of oscillation of discharg e during infusion of both agents together may be completely accounted for by a combined effect of increased carbon dioxide production and el evated [K+]a.