Interplay of Oxidative Stress and Nitric Oxide Synthase Gene Expression on Cardiovascular Responses in Preeclampsia / Interação do estresse oxidativo e da expressão dos genes das óxido nítrico sintases nas respostas cardiovasculares na pré-eclâmpsia

Abstract Objective To assess the influence of oxidative stress on the gene expression of nitric oxide synthases (NOS 3 and NOS 2) and, hence, the cardiovascular responses in preeclampsia. Methods This was a case control study in which patients with preeclampsia (PE group) and normal pregnancy controls (NP group) were included according to the guidelines of the American College of Obstetricians and Gynecologists (ACOG). The serum levels of malondialdehyde (MDA), total antioxidant capacity, and nitric oxide (NO) were estimated, and the heart rate andmean arterial pressure were recorded. The gene profiling of NOS3 and NOS2 was performed through real-time polymerase chain reaction (RT-PCR). The statistical analysis was performed using the Student t-test, and values of p<0.05 were considered statistically significant. Results The serum levels of malondialdehyde were increased (p<0.0001), and the total antioxidant capacity was reduced in the PE group (p=0.034), indicating oxidative stress. In the PE group, themean arterial pressure was significantly higher (p<0.0001), but the serum levels of NO did not show a statistically significant reduction (p=0.20). The gene expression profiling of NOS3 and NOS2 revealed a down regulation in the PE group by 8.49 and 51.05 times respectively. Conclusion Oxidative stress may lead to endothelial dysfunction, which could result in increased mean arterial pressure. Nitric oxide may play a role in this mechanism, but interactions with other vasoactive /biological substances cannot be overlooked, as the gene expression of NOS3 and NOS2 has been reduced.

Resumo Objetivo Avaliar a influência do estresse oxidativo na expressão genética das óxido nítrico sintases (nitric oxide synthases, NOS, em inglês; NOS 3 e NOS 2) e, consequentemente, nas respostas cardiovasculares na pré-eclâmpsia. Métodos Este foi um estudo caso-controle no qual pacientes com pré-eclâmpsia (grupo PE) e controles comgravidez normal (grupo GN) foramincluídos de acordo com as diretrizes do American College of Obstetricians and Gynecologists (ACOG). Foram estimados os níveis séricos de malondialdeído (MDA) da capacidade antioxidante total, e de óxido nítrico (nitric oxide, NO, em inglês). A frequência cardíaca e a pressão arterial média foram registradas. O perfil genético da NOS3 e da NOS2 foi feito por reação em cadeia de polimerase em tempo real (real-time polymerase chain reaction, RT-PCR, em inglês). A análise estatística foi feita utilizando-se o teste t de Student, e valores de p<0,05 foram considerados estatisticamente significativos. Resultados Os níveis séricos de malondialdeído sérico estavam aumentados (p<0,0001), e a capacidade antioxidante total, reduzida no grupo PE (p=0,034), o que indicava estresse oxidativo. No grupo PE, a pressão arterial média era significativamente maior (p<0,0001), mas os níveis séricos de NO não demostraram redução estatisticamente significativa (p=0,20). O perfil de expressão genética da NOS3 e da NOS2 revelou uma regulação negativa no grupo PE de 8,49 e 51,05 vezes, respectivamente. Conclusão O estresse oxidativo pode levar à disfunção endotelial, o que pode resultar em aumento da pressão arterialmédia. O NO pode desempenhar umpapel neste mecanismo, mas as interações com outras substâncias vasoativas/biológicas não podem ser negligenciadas, uma vez que a expressão genética da NOS3 e da NOS2 foi reduzida.

Diurnal variation of vascular diameter and reactivity in healthy young men

The higher incidence of cardiovascular events in the morning is accompanied by an increased vascular tone. However, there are few published studies designed to evaluate the diurnal variation of vascular and endothelial parameters in healthy subjects. In the present investigation, we evaluated the diurnal variation in brachial artery diameter (BAD), flow-mediated dilation (FMD) and endothelium-independent dilation (NFMD) in a homogeneous sample of healthy non-smoker young men. Fifty subjects aged 20.8 ± 0.3 years (range: 18 to 25 years) were investigated by brachial artery ultrasound. Exclusion criteria were female gender and evidence of clinically significant health problems, including obesity. Volunteers were asked to rest and avoid fat meals as well as alcoholic beverages 48 h before and until completion of the evaluations. BAD, FMD and NFMD were measured at 7 am, 5 pm, and 10 pm and tested by repeated measures ANOVA. BAD was smaller at 7 am (mean ± SEM, 3.8 ± 0.1 mm) in comparison with 5 pm (3.9 ± 0.1) and 10 pm (4.0 ± 0.1 mm; P < 0.001). FMD values did not change significantly during the day, while NFMD increased more at 7 am (18.5 ± 1.1 percent), when compared to 15.5 ± 0.9 percent at 10 pm and 15.5 ± 0.9 percent at 5 pm (P = 0.04). The physiological state of vasoconstriction after awakening, with preserved capability to dilate in the morning, should be considered to be part of the healthy cardiovascular adaptation before considering later life risk factors and endothelial dysfunction.

Human saphenous vein organ culture under controlled hemodynamic conditions

INTRODUCTION: Saphenous vein grafting is still widely used to revascularize ischemic myocardium. The effectiveness of this procedure is limited by neointima formation and accelerated atherosclerosis, which frequently leads to graft occlusion. A better understanding of this process is important to clarify the mechanisms of vein graft disease and to aid in the formulation of strategies for prevention and/or therapeutics. OBJECTIVE: To develop an ex vivo flow system that allows for controlled hemodynamics in order to mimic arterial and venous conditions. METHODS: Human saphenous veins were cultured either under venous (flow: 5 ml/min) or arterial hemodynamic conditions (flow: 50 ml/min, pressure: 80 mmHg) for 1-, 2- and 4-day periods. Cell viability, cell density and apoptosis were compared before and after these intervals using MTT, Hoeschst 33258 stain, and TUNEL assays, respectively. RESULTS: Fresh excised tissue segments were well preserved prior to the study. Hoechst 33258 and MTT stains showed progressive losses in cell density and cell viability in veins cultured under arterial hemodynamic conditions from 1 to 4 days, while no alterations were observed in veins cultured under venous conditions. Although the cell density from 1-day cultured veins under arterial conditions was similar to that of freshly excised veins, the TUNEL assay indicated that most of these cells were undergoing apoptosis. CONCLUSION: The results observed resemble the events taking place during early in vivo arterial-vein grafting and provide evidence that an ex vivo perfusion system may be useful for the identification of new therapeutic targets that ameliorate vein graft remodeling and increase graft patency over time.