RT info:eu-repo/semantics/article
T1 Muscarinic receptor localization and function in rabbit carotid body
A1 Dinger, Bruce
A1 Almaraz Gómez, Laura
A1 Hirano, T.
A1 Yoshizaki, Katsuaki
A1 González, Constancio
A1 Gómez Niño, María Ángeles
A1 Fidone, Salvatore
K1 Neurofisiología
AB Acetylcholine and muscarinic agonists inhibit chemosensory activity in the rabbit carotid sinus nerve (CSN). Because the mechanism ofthis inhibition is poorly understood, we have investigated the kinetics and distribution of muscarinic receptors in the rabbit carotid body withthe specific muscarinic antagonist [SH]quinuclidinylbenzitate ([3H]QNB). Equilibrium binding experiments identified displaceable binding sites(1/~M atropine) with a K d = 71.46 pM and a Bm~ x = 9.23 pmol/g tissue. These binding parameters and the pharmacology of the displaceable[SH]QNB binding sites are similar to specific muscannic receptors identified in numerous other nervous, muscular and glandular tissues.Comparisons of specific binding in normal and chronic CSN-denervated carotid bodies suggest that musearinic receptors are absent on afferentterminals in the carotid body; however, nearly 50% of the specific [3H]QNB binding is lost following chronic sympathectomy, suggestingthe presence of presynaptic muscarinic receptors on the sympathetic innervation supplying the carotid body vasculature. Autoradiographicstudies have localized the remainder of [3H]QNB binding sites to Iobules of type I and type II parenchymal cells. In separateexperiments, the muscarinic agonists, oxotremorine (100/~M) and bethanechol (100 ~tM) were shown to inhibit both the release of catecholaminesand the increased CSN activity evoked by nicotine (50/~M) stimulation of the in vitro carotid body, Our data suggest that muscarinicinhibition in the rabbit carotid body is mediated by receptors located on type I cells which are able to modulate the excitatory actionsof acetylcholine at nicotinic sites.
PB Elsevier
SN 0006-8993
YR 1991
FD 1991
LK http://uvadoc.uva.es/handle/10324/6843
UL http://uvadoc.uva.es/handle/10324/6843
LA eng
NO Brain Research, 1991, vol.562, p.190-198
NO Producción Científica
DS UVaDOC
RD 22-nov-2024