Bioelectric potentials in the carotid body.
Simultaneous recordings of focal slow potentials (sVs) and chemosensory discharges were made from cat carotid body-nerve preparations in situ. Chemoreceptor stimulants (100% N2, asphyxia, NaCN, ACh and nicotine), and depressants (100% O2, spontaneous gasps and dopamine) changed receptor polarization. sVs evoked by stimulants had a negative polarity whereas depressants elicited positive deflections. There was a direct correlation between maximal frequency of chemosensory discharges and peak sV amplitude when NaCN injections or N2 inhalation were used. However, cholinergic agents, dopamine and substance P evoked sVs which lacked correlation in time-course, amplitude or polarity with changes in sensory frequency. After a 6-day carotid nerve crush, different stimuli still evoked sVs even in the absence of sensory discharges. Both sVs and chemosensory discharges were abolished after 1 h ischemia produced by ligature of carotid body blood vessels. Thus, sVs from carotid body chemoreceptors probably include a neuronal component (the generator potential) directly responsible for the origin of chemosensory discharges, and a non-neuronal component (receptor or secretory potentials) probably originating in glomus and/or sustentacular cells.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002344:Carotid Body / Q000187:drug effects / Q000502:physiology*; D002415:Cats; D004298:Dopamine / Q000494:pharmacology; D005071:Evoked Potentials; D009538:Nicotine / Q000494:pharmacology; D009584:Nitrogen / Q000494:pharmacology; D010100:Oxygen / Q000097:blood; D012966:Sodium Cyanide / Q000494:pharmacology
D002245:Carbon Dioxide; D009538:Nicotine; D009584:Nitrogen; D000109:Acetylcholine; D012966:Sodium Cyanide; D010100:Oxygen; D004298:Dopamine