Dual effects of dopamine upon chemosensory responses to cyanide

Changes in chemosensory responses to i.v. NaCN during i.v. infusions of dopamine (DA) were studied in pentobarbitone-anesthetized cats. After sectioning both carotid nerves, one of them was prepared for electrophysiological recordings of its chemosensory impulses. Basal chemosensory activity was maintained at a reduced level during DA infusions at a rate of 10 micrograms/kg/min. While sensitivity to NaCN was not modified, reactivity to this agent was reduced for low doses, but enhanced for high doses. It is concluded that chemoreceptor responses to histotoxic hypoxia are rectified by DA. This is discussed in terms of a modulatory role of endogenous DA in the generation of carotid body sensory impulses.