Some characteristics of baclofen-evoked responses of primary afferents in frog spinal cord.
Brain Res
; 516(2): 201-7, 1990 May 21.
Article
en En
| MEDLINE
| ID: mdl-2364287
Baclofen has been shown to be a selective agonist for a subclass of GABA receptors (GABAB) in many regions of the vertebrate nervous system. On the intraspinal terminals of dorsal roots (DRT), it evokes a pure hyperpolarizing response. We have previously shown that the response of DRT to GABA and some of its analogs (e.g. kojic amine) in isolated frog spinal cord is dual in nature, consisting of a bicuculline-sensitive depolarizing component and a bicuculline-resistant hyperpolarizing component. Under the working hypothesis that the hyperpolarizing component of the GABA-evoked response is mediated by the activation of GABAB receptors, we have examined, using the sucrose gap technique, some characteristics of the response of DRT to baclofen. We have found that this response is stereospecific (L-baclofen being about 100 times more potent than D-baclofen), dependent on [K]o (response amplitude inversely related to [K]o), blocked by barium (0.5 mM causing a reduction of the response amplitude to 37% of control), and is not significantly affected by 4-aminopyridine, nor by inorganic calcium channel blockers (manganese, cobalt, cadmium). Some proposed GABAB antagonists (delta-aminovaleric acid, delta-aminolaevulinic acid, phaclofen) are also rather ineffective at blocking it. These results are therefore consistent with the notion that the baclofen-evoked response of DRT is mediated by an increase in conductance to potassium ions.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Potasio
/
Médula Espinal
/
Baclofeno
/
Neuronas Aferentes
Límite:
Animals
Idioma:
En
Revista:
Brain Res
Año:
1990
Tipo del documento:
Article
País de afiliación:
Canadá
Pais de publicación:
Países Bajos