Papers by Maria Cristina Breno
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Com o objetivo de caracterizar o receptor de angiotensina presente n sistema cardiovascular da se... more Com o objetivo de caracterizar o receptor de angiotensina presente n sistema cardiovascular da serpente Bothrops jararaca, foram realizados estudos funcionais e com radioligantes em aneis de aorta e na musculatura cardiaca dessa serpente. Os tres octapeptideos estudados produziram efeito contratil em aorta, com valores de pD2 de: 7,52 n O,17 [Asp1 , lle]All; 8,08 n O,10 [Asp1, Val5 ]All; 5,99 n O,05 [Asn1, Val5 ]All. A ordem de potencia dos analogos de angiotensina foi:[Asp1 , Val5 ]All > [Asp1, lle5]All >>> [Asn1 , Val5 ]All, diferente do observado para outros vertebrados. [Sar1, lle8]All, antagonista nao seletivo, losartan, antagonista seletivo AT1, e PDl23319, antagonista seletivo AT2, causaram deslocamento para a direita da curva concentracao-efeito de [Asp1, lle5 ]All com diminuicao do efeito maximo. Os valores de pKB foram, respectivamente, 5,16 n O,09; S,67 n O,31; 5,18 n O,62, os quais estao acima dos valores de pA2 e pKi3 descritos na literatura para estes antag...
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Comparative Biochemistry and Physiology Part A: Physiology, 1994
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Comparative Biochemistry and Physiology Part A: Physiology, 1992
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Life Sciences, 2012
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Journal of Comparative Physiology B, 2006
We used four complementary techniques to investigate the presence of oxytocin peptide in the hypo... more We used four complementary techniques to investigate the presence of oxytocin peptide in the hypophysis and brain of the snake Bothrops jararaca. A high-pressure liquid chromatographic analysis failed to show oxytocin in extracts of hypophysial and brain tissues but provided estimative values of the amounts of vasotocin (12 ng/mg hypophysis and 0.5 ng/mg brain) and mesotocin (500 pg/mg hypophysis and 8 pg/mg brain). Western blots with a polyclonal anti-oxytocin antibody failed to detect oxytocin in both tissues but detected compounds with higher molecular weight than oxytocin, as well as a relatively weak cross-reactivity with mesotocin. The reverse transcription-polymerase chain reaction analysis failed to detect the expression of oxytocin gene transcript, but detected a transcript related to the mesotocin-neurophysin precursor in both tissues. Immunohistochemistry with the same anti-oxytocin antibody detected strong staining in the neurohypophysis and in few fibers in the inner zone of the median eminence, which was not abolished by pre-adsorption of this antibody with oxytocin, vasopressin, vasotocin or mesotocin and might not be attributed to oxytocin. In conclusion, our data demonstrate the absence of oxytocin in the central nervous system of the snake B. jararaca and underline the pitfalls that can result from the use of a single technique to investigate the presence of peptides in tissues.
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European Journal of Pharmacology, 2001
Angiotensin II interacts with specific cell surface angiotensin AT1 and AT2 receptors and, in som... more Angiotensin II interacts with specific cell surface angiotensin AT1 and AT2 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 Kd=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 AT1 and AT2 receptors. It seems to belong to a new class of angiotensin receptors, like some other atypical angiotensin AT receptors that have already been described.
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Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2009
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Gen Comp Endocrinol, 2004
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Experimental Biology and Medicine, Jun 1, 2006
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Journal of Chemical Neuroanatomy, 2002
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Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
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Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
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Gen Comp Endocrinol, 2004
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General and Comparative Endocrinology, 2004
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General and Comparative Endocrinology, 2004
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Papers by Maria Cristina Breno