Beta 1-, beta 2- and atypical beta-adrenoceptor-mediated relaxation in XXXX isolated aorta.

@entity1169 @entity10342 @entity30828 @entity3047 @entity72381 @entity14528 @entity3046 @entity3044 @entity72380 @entity18635 @entity44487 @entity35 @entity10341 @entity1063
beta-adrenoceptor-mediated relaxation was investigated in ring preparations of @entity35 isolated thoracic aorta. Rings were pre-constricted with a sub-maximal concentration of @entity1063 (1 microM) and relaxant responses to cumulative concentrations of beta-adrenoceptor agonists obtained. The concentration-response curve (CRC) to @entity3044 was shifted to the right by @entity1169 (0.3 microM) with a steepening of the slope. Estimation of the magnitude of the shift from EC(50) values gave a pA(2) of 7.6. Selective beta(1)- and @entity10341 antagonists, @entity14528 (0.1 microM) and @entity10342 (0.1 microM), respectively, produced 4 and 14 fold shifts of the @entity3044 CRC. Atypical beta-adrenoceptor agonists also produced concentration-dependent relaxation of aortic rings. The order of potency of the beta-adrenoceptor agonists was (-log EC(50)): @entity3044 (6. 25)> @entity30828 (5.59)> @entity3044 + @entity1169 (5.11)> @entity3046 (4.40)> @entity72380 (4.24)> @entity72381 (4.07)> @entity3047 (3.89). Relaxation to @entity3046 and @entity72381 was unaffected by @entity1169 (0.3 microM). SR 59230A (</=1 microM) and @entity30828 (1 microM), @entity18635 antagonists, had no effect on the @entity3044 (in the presence of @entity1169 ) or @entity3046 CRCs. @entity44487 and @entity14528 , at microM concentrations (beta(4)-adrenceptor antagonists), inhibited responses to @entity3044 (in the presence of @entity1169 ) and @entity3046 . In conclusion, atypical beta-adrenoceptors co-exist with beta(1)- and beta(2)-adrenoceptors in @entity35 aorta. Although non-conventional partial agonists and selective @entity18635 agonist cause relaxation, the vascular atypical beta-adrenoceptor does not appear to correspond to the @entity18635 . There are, however, similarities with the putative beta(4)-adrenoceptor.
