Effects of 6-hydroxy-dopamine on carotid body chemosensory activity.

6-OH-DA HBr 5-25 mg injected into one common carotid artery of pentobarbitone-anesthetized cats, induced a transient inhibition of chemosensory discharges recorded from the ipsilateral carotid nerve, but did not change chemosensory frequency during spontaneous ventilation, periodic deep breaths and asphyxia. Chemosensory activities recorded simultaneously from both carotid nerves showed no differences in their inhibitory responses to dopamine and their excitatory responses to NaCN, up to 48 h after the injections of 6-OH-DA. It is concluded that 6-OH-DA acts initially as a dopamine analogue, and does not impair subsequent carotid body chemoreception or dopamine-induced inhibition, as doses producing abolition of noradrenergic transmission.