Navegando por Palavras-chave "adenylylcyclase forskolin-sensitive"

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    Angiotensin receptor in the heart of Bothrops jararaca snake
    (Elsevier B.V., 2001-04-06) Breno, M. C.; Porto, C. S.; Picarelli, Z. P.; Universidade Federal de São Paulo (UNIFESP); Inst Butantan
    Angiotensin II interacts with specific cell surface angiotensin AT(1) and AT(2) receptors and, in some vertebrates, with an atypical angiotensin AT receptor. This study was designed to characterize the angiotensin receptor in the heart of Bothrops jararaca snake. A specific and saturable angiotensin II binding site was detected in cardiac membranes and yielded K-d = 7.34 +/- 1.41 nM and B-max = 72.49 +/- 18 fmol/mg protein. Competition-binding studies showed an angiotensin receptor with low affinity to both angiotensin receptor antagonists, losartan (2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H-tetrazol-5-yl)biphenyl-4-yl)methyl]imidazole) and PD123319 ((s)-1-(4-[dimethylamino]-3-methylphenyl)methyl-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylate). Studies on the intracellular signaling pathways showed that phospholipase C/inositol phosphate breakdown and adenylylcyclase/cyclic AMP generation were not coupled with this angiotensin receptor. An adenylylcyclase enzyme sensitive to forskolin was detected. the results indicate the presence of an angiotensin receptor in the heart of B. jararaca snake pharmacologically distinct from angiotensin AT(1) and AT(2) receptors. It seems to belong to a new class of angiotensin receptors, like some other atypical angiotensin AT receptors that have already been described. (C) 2001 Elsevier Science B.V. All rights reserved.