Autor(es):
Talaia, C 
; Queiroz, G ; Quintas, C ; Gonçalves, J
Data: 2005
Identificador Persistente: http://hdl.handle.net/10216/73703
Origem: Repositório Aberto da Universidade do Porto
Detalhes do Documento
Interaction between adenosine A(2B)-receptors and alpha(2)-adrenoceptors on the...
Descrição
In the prostatic portion of rat vas deferens, activation of adenosine A(2B)-receptors, beta(2)-adrenoceptors, adenylyl cyclase or protein kinase A caused a facilitation of noradrenaline release. Blockade of alpha(2)-adrenoceptors with yohimbine (1 mu M) attenuated the facilitation mediated by adenosine A(2B)-receptors and by direct activation of adenylyl cyclase with forskolin but not that mediated by beta(2)-adrenoceptors or by direct activation of protein kinase A with 8-bromoadenosine-3,5-cyclicAMP. The adenosine A(2B)- and the beta(2)-adrenoceptor-mediated facilitation was prevented by the adenylyl cyclase inhibitors, 2,5-dideoxyadenosine (3 mu M) and 9-cyclopentyladenine (100 mu M), at concentrations that also attenuated the release enhancing effect of forskolin, but were not changed by the phospholipase C inhibitor 1-[6-[((17 beta)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione (U-73122, 1 mu M). Facilitation of noradrenaline release mediated by adenosine A-B-receptors was also attenuated by activation of protein kinase C with the phorbol ester 12-myristate 13-acetate (1 mu M) and by inhibition of G beta gamma subunits with an anti-beta gamma peptide; facilitation mediated by beta(2)-adrenoceptors was mainly attenuated by the calmodulin inhibitor calmidazolium (10 mu M) and by the calmodulin kinase II inhibitor (N-[2-[N-(4-chlorocinnamyl)-N-methylaminomethyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzene-sulfonamide phosphate (KN-93, 5 mu M). The results suggest that adenosine A(2B)- but not beta(2)-adrenoceptor-mediated facilitation of noradrenaline release is enhanced by an ongoing activation of alpha(2)-adrenoceptors. They further suggest that adenosine A(2B)-receptors and beta(2)-adrenoceptors are coupled to distinct adenylyl cyclase isoforms what may explain the different influence of alpha(2)-adrenoceptor signalling pathway on the facilitatory effects mediated by the two adenylyl cyclase coupled receptors. (c) 2005 Elsevier Ltd. All rights reserved.
In the prostatic portion of rat vas deferens, activation of adenosine A(2B)-receptors, beta(2)-adrenoceptors, adenylyl cyclase or protein kinase A caused a facilitation of noradrenaline release. Blockade of alpha(2)-adrenoceptors with yohimbine (1 mu M) attenuated the facilitation mediated by adenosine A(2B)-receptors and by direct activation of adenylyl cyclase with forskolin but not that mediated by beta(2)-adrenoceptors or by direct activation of protein kinase A with 8-bromoadenosine-3,5-cyclicAMP. The adenosine A(2B)- and the beta(2)-adrenoceptor-mediated facilitation was prevented by the adenylyl cyclase inhibitors, 2,5-dideoxyadenosine (3 mu M) and 9-cyclopentyladenine (100 mu M), at concentrations that also attenuated the release enhancing effect of forskolin, but were not changed by the phospholipase C inhibitor 1-[6-[((17 beta)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione (U-73122, 1 mu M). Facilitation of noradrenaline release mediated by adenosine A-B-receptors was also attenuated by activation of protein kinase C with the phorbol ester 12-myristate 13-acetate (1 mu M) and by inhibition of G beta gamma subunits with an anti-beta gamma peptide; facilitation mediated by beta(2)-adrenoceptors was mainly attenuated by the calmodulin inhibitor calmidazolium (10 mu M) and by the calmodulin kinase II inhibitor (N-[2-[N-(4-chlorocinnamyl)-N-methylaminomethyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzene-sulfonamide phosphate (KN-93, 5 mu M). The results suggest that adenosine A(2B)- but not beta(2)-adrenoceptor-mediated facilitation of noradrenaline release is enhanced by an ongoing activation of alpha(2)-adrenoceptors. They further suggest that adenosine A(2B)-receptors and beta(2)-adrenoceptors are coupled to distinct adenylyl cyclase isoforms what may explain the different influence of alpha(2)-adrenoceptor signalling pathway on the facilitatory effects mediated by the two adenylyl cyclase coupled receptors. (c) 2005 Elsevier Ltd. All rights reserved.
Tipo de Documento
Artigo
Idioma Inglês
Idioma Inglês
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