Endothelin-1 induced proinflammatory markers in the myocardium and leukocytes of guinea-pigs: role of glycoprotein IIB/IIIA receptors.

AIM: To assess whether endothelin-1 (ET-1) induces the in vivo expression of inflammatory-related proteins, namely cyclooxygenase-2 (COX-2) and tissue factor, in the myocardium and circulating leukocytes of guinea-pigs. The involvement of platelets was also analyzed. METHODS: ET-1 (0.013 microg/min) was infused to male guinea-pigs for 45 min in the presence and absence of tirofiban, a nonpeptidic blocker of the glycoprotein IIb/IIIa receptor (GPIIb/IIIa). Tissue factor and COX-2 expression were determined by Western blot. RESULTS: No changes in mean arterial pressure and heart rate were detected. ET-1-infused guinea-pigs showed a marked increase in the number of platelets expressing activated GPIIb/IIIa receptors (0.8+/-0.03% vs. 6.5+/-0.2%; P<0.05). Tirofiban (10 microg/Kg bw/min) blunted ex vivo platelet aggregation in response to ADP, although only partially reduced COX-2 and tissue factor expression in both the myocardium and leukocytes of ET-1-infused guinea-pigs. The myocardium of platelet-depleted guinea-pigs also showed a reduced COX-2 expression after ET-1 infusion (57+/-3% reduction; P<0.05). In vitro studies demonstrated that platelets (10(7) and 10(9) platelets/well) enhanced ET-1 (10(-7) mol/l)-induced COX-2 expression in heart slices. CONCLUSION: ET-1 stimulated in vivo the expression of the pro-inflammatory proteins COX-2 and tissue factor in the myocardium and in leukocytes by a mechanism GPIIb/IIIa platelet receptors.

[Effect of HMG-CoA reductase inhibition on endothelial dysfunction-inducing protein in hypercholesterolemic rabbits]. / Efecto de la inhibición de la HMG-CoA reductasa sobre la proteína inductora de disfuncion endotelial en conejos hipercolesterolémicos.

INTRODUCTION AND OBJECTIVES: In our laboratory, we recently obtained evidence that cultured bovine endothelial cells contain cytosolic proteins that form complexes with the 3'-unstranslated region of endothelial nitric oxide synthase (eNOS) mRNA and are associated with its destabilization. The aim of this study was to determine the presence of such proteins and the level of eNOS expression in hypercholesterolemic rabbits as an in vivo model of endothelial dysfunction. METHODS AND RESULTS: Endothelium-dependent relaxation in response to acetylcholine was reduced in aortic segments from hypercholesterolemic rabbits compared with controls. Treatment of hypercholesterolemic rabbits with simvastatin (25 mg/kg body weight/day) restored endothelium-dependent relaxation. Aortic eNOS expression was reduced in hypercholesterolemic rabbits and was accompanied by enhanced binding activity of a 60-KDa cytosolic protein and reduced stability of eNOS mRNA. Simvastatin treatment upregulated eNOS expression and reduced the interaction of cytosolic protein with the 3'-untranslated region of eNOS mRNA. CONCLUSIONS: These results demonstrate the presence of a 60-KDa protein that binds to eNOS mRNA and reduces eNOS expression in the vascular wall.

Efecto de la inhibición de la HMG-CoA reductasa sobre la proteína inductora de disfunción endotelial en conejos hipercolesterolémicos / Effect of HMG-CoA reductase inhibition on endothelial dysfunction-inducing protein in hypercholesterolemic rRabbits

Introducción y objetivos. Recientemente se ha demostrado en nuestro laboratorio que las células endoteliales en cultivo expresan proteínas citosólicas que forman complejos con el ARNm de la óxido nítrico sintasa endotelial (NOSe) en la región 3' que no codifica para proteína (3'-UTR). Esta unión fue asociada con la desestabilización del ARNm de dicha enzima. El objetivo de este estudio fue determinar la presencia de estas proteínas citosólicas y el nivel de expresión de la proteína NOSe en la pared vascular de conejos hipercolesterolémicos como un modelo in vivo de disfunción endotelial. Métodos y resultados. La relajación dependiente del endotelio a acetilcolina estuvo reducida en segmentos aórticos de conejos hipercolesterolémicos comparados con los conejos control. El tratamiento de los conejos hipercolesterolémicos con simvastatina (25 mg/kg peso/día) restauró la relajación dependiente del endotelio.La expresión de NOSe se encontró reducida en la pared vascular de los conejos hipercolesterolémicos, lo cual se acompañó de un aumento en la capacidad de unión de la proteína citosólica de 60 kDa y de una reducción en la estabilidad del ARNm de la NOSe. El tratamiento con simvastatina aumentó la expresión de NOSe y redujo la interacción de la proteína citosólica a la región 3'-UTR del ARNm de la NOSe. Conclusiones. Estos resultados demuestran una relación entre la presencia de la proteína de 60 kDa y la abundancia de NOSe en la pared vascular y la funcionalidad endotelial (AU)

Sevoflurane reduces endothelium-dependent vasorelaxation: role of superoxide anion and endothelin.

PURPOSE: There are several reports suggesting that volatile anesthetics alter vascular endothelial function. We analyzed the effect of sevoflurane, a fluorinated volatile anesthetic, on nitric oxide (NO)-dependent relaxation, evaluating the role of the endothelium-derived vasoconstrictor endothelin-1 (ET-1). METHODS: The experiments were performed in rat isolated aortic segments aerated in the absence and in the presence of sevoflurane (2%). RESULTS: Acetylcholine-induced relaxation was reduced in aortic segments aerated with sevoflurane. Sevoflurane failed to modify relaxation in response to an exogenous NO donor, sodium nitroprusside. Superoxide dismutase, a scavenger of superoxide anion, partially restored the impaired vasorelaxation induced by sevoflurane, an effect that was associated with the release of superoxide anion. The presence of BQ-123, an antagonist of endothelin ETA-type receptors, normalized the vasorelaxing response to acetylcholine in the presence of sevoflurane. In addition, BQ-123 also reduced the ability of the sevoflurane-incubated vascular wall to release superoxide anion. CONCLUSIONS: Our results suggest that sevoflurane impairs the endothelium-dependent vasorelaxation but that the endothelium-independent response remains intact. ET-1 and superoxide anion are involved in the endothelial dysfunction induced by sevoflurane. Further studies are needed to associate the endothelial dysfunction related to sevoflurane shown herein and its reported preconditioning properties on the myocardium.

Alteration of the soluble guanylate cyclase system in the vascular wall of lead-induced hypertension in rats.

Low-level lead exposure is a known cause of hypertension that has been associated with increased reactive oxygen species activity and endothelial-dependent vasorelaxation impairment. The effect of lead exposure on the vascular nitric oxide (NO)/cyclic guanocine monophosphate (cGMP) system was analyzed. Wistar rats were exposed to 5 ppm lead acetate in the drinking water during 30 d. Mean arterial BP increased significantly in the lead-treated rats. Relaxation to both acetylcholine and sodium nitroprusside (SNP) was reduced in lead-treated rats; however, the vascular wall of lead-administered rats showed an increased expression of endothelial NO synthase. The expression of both subunits (alpha(1) and beta(1)) of soluble guanylate cyclase (sGC) and the cGMP accumulated in the vascular wall were decreased in lead-treated rats. Cotreatment of lead with vitamin C (3 mmol/L) prevented the increase on mean arterial BP, improved the relaxation to both acetylcholine and sodium nitroprusside, and restored the normal expression of endothelial NO synthase and sGC proteins in the vascular wall. In conclusion, lead exposure altered both the endothelium-dependent and -independent relaxing response and induced a reduced expression of sGC in the vascular wall. These effects were abrogated with the antioxidant vitamin C, which suggests the involvement of reactive oxygen species in the regulation of the NO/cGMP relaxing system in the vascular wall of lead-treated rats.