Alteration of chemoreflex phrenic responses by oligomycin in the rabbit.

The effects of carotid chemoreceptor stimulation by intracarotid injections of sodium cyanide (NaCN, 30 micrograms), antimycin A (AMC, 10 micrograms) and dopamine (DA, 10 micrograms) on phrenic nerve activity were studied before and after oligomycin (200 micrograms) in the rabbit. The excitatory responses to NaCN and AMC were abolished after intracarotid administration of oligomycin, whereas the DA-induced phrenic depression was only slightly diminished. In addition, the effects of hypoxia on phrenic nerve activity were also studied before and after oligomycin (200 micrograms) in some animals with denervated one carotid sinus nerve. The hypoxia-induced phrenic excitation was greatly reduced after intracarotid administration of oligomycin. These results indicate that the chemoreflex phrenic responses induced by NaCN, AMC and hypoxia are probably related to the phosphate potential in the carotid body.