Lack of correlation between cholinergic-induced changes in chemosensory activity and dopamine release from the cat carotid body in vitro.
We studied the effects of nicotine, acetylcholine (ACh) and dopamine (DA) on the frequency of chemosensory discharges (f(x)) and catecholamine (CA) efflux in the cat carotid body superfused in vitro. CA efflux was measured by changes in CA concentration (DeltaCA) determined by chronoamperometry with nafionated carbon-fiber microelectrodes inserted in the carotid body, while f(x) was recorded simultaneously from the carotid (sinus) nerve. Nicotine (10-20 microg) and ACh (>100 microg) increased f(x) in all carotid bodies (n=16), but produced a delayed DeltaCA ( approximately 0.65 microM) in only half of them. Eserine potentiated ACh-evoked increases in f(x) and CA effluxes. Nicotine and ACh-induced DeltaCA were rapidly reduced upon repeated administration. While f(x) increases evoked by low doses of nicotine or ACh were reduced or abolished by prior administration of exogenous DA (>100 microg), CA effluxes were enhanced and hastened. Thus, cholinergic-induced changes in f(x) are dissociated from CA efflux.
Iturriaga
R
R
Laboratorio de Neurobiología, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 1, Santiago, Chile. riturria@genes.bio.puc.cl
Alcayaga
J
J
Zapata
P
P
D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002344:Carotid Body / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002415:Cats; D002628:Chemoreceptor Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009538:Nicotine / Q000494:pharmacology
D009538:Nicotine; D000109:Acetylcholine; D004298:Dopamine