The mucosal potential elicited by noxious chemical stimuli with CO2 in rats: is it a peripheral nociceptive event?
Negative mucosal potentials (NMPs) were recorded from the nasal respiratory mucosa in rats following retrograde stimulation with CO2 through a tube advanced to the nasopharynx. Local application of capsaicin (3 mg in 0.3 ml solvent, n = 5) and lidocaine (31 mg in 0.3 ml solvent, n = 5) eliminated the NMPs and cortical responses in the EEG. A quantitative reduction in NMPs was found following systemic pretreatment with capsaicin (cumulative dose, 200 mg/kg, n = 4), but not with guanethidine (50 mg/kg s.c., n = 4). Blood flow measurements and NMPs were obtained from the same recording position (n = 4). Onset of blood flow changes (1200-4800 ms) appeared significantly later than the onset of NMPs (120-500 ms). On the basis of these results a sensory neurogenic origin of the NMP is assumed.
Thürauf
N
N
Department of Pharmacology and Toxicology, University of Erlangen-Nuernberg, F.R.G.
Friedel
I
I
Hummel
C
C
Kobal
G
G
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D002245:Carbon Dioxide / Q000494:pharmacology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000187:drug effects; D006145:Guanethidine / Q000494:pharmacology; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009297:Nasal Mucosa / Q000502:physiology*; D009474:Neurons / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects*; D010525:Peripheral Nerves / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects; D014276:Trigeminal Nerve / Q000502:physiology
D002245:Carbon Dioxide; D008012:Lidocaine; D002211:Capsaicin; D006145:Guanethidine