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- Title
Role of β<sub>2</sub>-adrenoceptors (ß-AR), but not ß<sub>1</sub>-, β<sub>3</sub>-AR and endothelial nitric oxide, in β-AR-mediated relaxation of rat intrapulmonary artery.
- Authors
Pourageaud, Fabrice; Leblais, Véronique; Bellance, Nadège; Marthan, Roger; Muller, Bernard
- Abstract
The aim of this study was to analyze ß-adrenoceptor (ß-AR)-mediated relaxation in rat intralobar pulmonary artery. The relaxant responses of ß-AR agonists were characterized using ß-AR antagonists in prostaglandin F2α(PGF2α)-precontracted arteries. The role of nitric oxide (NO) and endothelium in ß-AR-mediated relaxation was also investigated. Isoprenaline (a non-selective ß-AR agonist) and salbutamol (a selective ß2-AR agonist) induced vasorelaxation. ICI 118551 (a selective ß2-AR antagonist) antagonized the effect of both isoprenaline and salbutamol (pA2 values of 9.57 and 9.51 respectively). In contrast, atenolol (1 μM) and CGP 20712A (0.1 μM), two ß1-AR antagonists, did not modify the relaxing effect of isoprenaline. The response to isoprenaline obtained in the presence of nadolol (10 μM, a ß1/ß2-AR antagonist) was not further inhibited by SR 59230A (1 μM, a selective ß3-AR antagonist). The non-ß1/ß2-AR agonists studied (BRL 37344, SR 58611A, and CGP 12177A) did not elicit vasorelaxation. Relaxation to isoprenaline and salbutamol was unaffected by L-NG-nitro-arginine methyl ester (100 μM, an inhibitor of NO synthase) or after endothelium removal. These results demonstrate the role of ß2-AR in mediating relaxation in rat intralobar pulmonary artery precontracted with PGF2α. They indicate that ß2-AR-mediated relaxation in this artery is NO- and endothelium-independent. Furthermore, they do not provide evidence of a relaxant role of either ß1-or ß3-AR in PGF2α-precontracted rat intrapulmonary artery.
- Subjects
BETA adrenoceptors; ADRENERGIC receptors; PULMONARY artery; ENDOTHELIUM; NITRIC-oxide synthases; NITRIC oxide
- Publication
Naunyn-Schmiedeberg's Archives of Pharmacology, 2005, Vol 372, Issue 1, p14
- ISSN
0028-1298
- Publication type
Article
- DOI
10.1007/s00210-005-1082-2