Plasma levels of nitrites, PGF1a and nitrotyrosine in LPS-treated rats: functional and histochemical implications in aorta

• Autores: O.H. Öztürk
• Localización: Journal of physiology and biochemistry, ISSN-e 1877-8755, ISSN 1138-7548, Vol. 62, Nº. 1, 2006, págs. 27-34
• Idioma: inglés
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• Resumen
  • español

    Se investigan los efectos de la administracion de lipopolisacarido (LPS) sobre los niveles plasmaticos de nitritos, nitrotirosina y 6- ceto-prostaglandina F1a (PGF1a) y los cambios histoquimicos y funcionales en aorta de rata. Los niveles plasmaticos de los citados compuestos se analizaron tras administracion intravenosa de 5 mg/Kg de LPS en comparacion con animales control. La distribucion de nitrotirosina en la aorta se estudio mediante inmunohistoquimica y las respuestas de anillos aorticos a la fenilefrina (FE) de ratas tratadas y control se midio en bano de organos. Los niveles plasmaticos de nitritos, nitrotirosina y PGF1a resultaron mayores en ratas tratadas que en las controles. Se detecto inmunorreactividad a residuos de nitrotirosina en el endotelio y en musculo liso de aorta de ratas tratadas, no de las control. La respuesta contractil a la fenilefrina de los anillos aorticos de ratas tratadas con LPS fue significativamente menor que la correspondiente a ratas control. La preincubacion de los anillos aorticos de ratas tratadas con indometacina (inhibidor de la ciclooxigenasa) o con una combinacion de indometacina y L-NAME (inhibidor de la nitrato sintasa) aumenta las respuestas contractiles hasta alcanzar los niveles de las ratas control, lo que sugiere que los prostanoides y el NO estan implicados en la reduccion de la respuesta contractil en ratas tratadas. Estos resultados parecen indicar que el LPS podria causar aumento de los niveles de NO y PGI2 que explicaria la reduccion en las respuestas contractiles en la aorta de las ratas tratadas con LPS

  • English

    We investigated the effects of lipopolysaccharide (LPS) administration on plasma nitrite, nitrotyrosine and 6-keto prostaglandin F1 (PGF1a) levels and the related resultant changes in function and histochemistry of aorta in rats.

    Plasma nitrite and PGF1a, nitrotyrosine levels were analysed after 5 mg/kg intravenous LPS was administered to rats compared with those in non-treated rats. The distribution of nitrotyrosine in the aorta was studied immunohistochemically. The contractile responses of aortic rings to phenylephrine (PE) from both the LPS-treated and control rats were studied in the organ baths.

    There were increases in plasma nitrite, PGF1a, and nitrotyrosine concentrations of LPS-treated rats compared to non-treated rats. Immunoreactivity of nitrotyrosine residues were detected in the endothelial and smooth muscle cells in LPS-treated but not in control rat aorta . The contractile responses to PE of the LPS-treated rat aortic rings were significantly reduced as compared with those of control rat's. Incubation of the aortic rings from LPS-treated rats with cyclooxygenase inhibitor indomethacine or with a combination of indomethacine and nitric oxide synthase inhibitor N -nitro-L-arginine methyl ester (L-NAME) increased the contractile responses to the levels observed in control rats suggesting that both prostanoids and particularly nitric oxide (NO) are involved in the reduced contractile responses in LPS-treated rats.

    These results supported the view that LPS might cause an increment in both NO and PGI2 levels. This increase in the NO and PGI2 levels may be responsible from the reduction in responses of aorta to contractile agents in LPS-treated rats. Increased peroxynitrite formation in LPS-treated rats may lead to nitration of the tyrosil residues of the proteins in the aorta.