Prejunctional opioid mu-receptors and adenosine A1-receptors on the sympathetic nerve endings of the rat tail artery interact with the alpha 2-adrenoceptors.
Naunyn Schmiedebergs Arch Pharmacol
; 345(1): 37-43, 1992 Jan.
Article
em En
| MEDLINE
| ID: mdl-1347155
ABSTRACT
Experiments were designed to study the interaction between prejunctional alpha 2-adrenoceptors and both adenosine and opioid receptors at the postganglionic sympathetic nerve endings innervating the tail artery of the rat. Segments of this vessel were preincubated with [3H]-noradrenaline and then perfused/superfused with [3H]-noradrenaline-free medium. Their perivascular nerves were field stimulated with standard stimulation parameters 24 pulses at 0.4 Hz, 0.3 ms, 200 mA. In some experiments, the stimulation parameters were adjusted in order to obtain similar reference release values despite the presence of a first release-modulating drug. The adenosine agonist 5'-N-ethylcarboxamidoadenosine (NECA; 0.3-10 mumol/l) and [D-Ala2,MePhe4,Glyol5]enkephalin (DAGO; 0.3-10 mumol/l) depressed the stimulation-evoked overflow of tritium in a concentration dependent manner. The release-inhibiting effect of both NECA and DAGO was enhanced in the presence of the alpha 2-adrenoceptor antagonist rauwolscine (3 mumol/1) while it was attenuated in the presence of the alpha 2-adrenoceptor agonist 5-bromo-6-[2-imidazolin-2yl-amino]-quinoxaline (UK-14,304; 0.1 mumol/l). These changes occurred both at standard and adjusted stimulation parameters. These results demonstrate that the prejunctional adenosine A1- and opioid mu-receptors interact with the prejunctional alpha 2-adrenoceptors. The level at which these interactions take place (receptors themselves or transduction mechanisms) as well as the physiological significance of the phenomenon remain to be determined.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fibras Autônomas Pós-Ganglionares
/
Receptores Purinérgicos
/
Receptores Adrenérgicos alfa
/
Receptores Opioides
Limite:
Animals
Idioma:
En
Revista:
Naunyn Schmiedebergs Arch Pharmacol
Ano de publicação:
1992
Tipo de documento:
Article
País de afiliação:
França