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Internal mammary artery (IMA) and radial artery (RA) are the 2 main arterial conduits used in coronary artery bypass grafting (CABG). The aim of this study was to analyze in vitro the vasoreactive properties in both vessels and to investigate the effects of pravastatin incubation on vascular function. IMA and RA rings obtained from patients undergoing CABG were studied in organ baths. We examined the contractile responses to phenylephrine and U46619 and the relaxation to acetylcholine (ACh) and sodium nitroprusside. In another series of experiments, the vascular reactivity and the superoxide anion production were studied after incubation with pravastatin. The effect of mevalonic acid on such responses was also assessed. Our results show that RA significantly evoked greater tension in response to vasoconstrictor agents and higher relaxation to ACh than IMA. In contrast, relaxation induced by sodium nitroprusside was not significantly different. Incubation with pravastatin reduced the contractile response to U46619 and improved the endothelium-dependent relaxation to ACh in both arteries. Whereas the effect of pravastatin on response to U46619 was completely abolished by coincubation with mevalonic acid, only a partial inhibition on ACh relaxation was observed. In conclusion, in vitro incubation with pravastatin enhanced endothelial function in IMA and RA. This suggests that postoperative (may include intraoperative) administration of statins could improve the endothelial function of arterial grafts in patients undergoing CABG.

The production of reactive oxygen species plays roles during the development of endothelial dysfunction and it represents a significant prognostic factor for evaluating the risk of cardiovascular disease. Although statins target cholesterol biosynthesis, the beneficial effects on cardiovascular disease remain to be fully elucidated. In this work, we explored the in vitro effects of pravastatin on vascular functionality. We studied the effect of the incubation with this statin on acetylcholine relaxation using aorta from spontaneously hypertensive rats (SHR). Consistent with a cholesterol-independent mechanism of action, we show that pravastatin induces a significant improvement of endothelium-dependent relaxation that is not completely reversed by mevalonic acid. Assays with 250microM of lucigenin were carried out to verify whether such action could be mediated by the scavenger properties of pravastatin. Treatment of aortic rings derived from Wistar rats with lucigenin promotes superoxide generation (O(2)(-)) and the subsequent loss of both endothelium-dependent and independent relaxations. The addition of pravastatin reduced the lucigenin-triggered O(2)(-) levels as well as its inhibitory effects on acetylcholine- and sodium nitroprusside-dependent responses. These effects were not counteracted by mevalonic acid, further supporting the idea that the effects of pravastatin do not entail alterations in cholesterol biosynthesis. In conclusion, this study can contribute to elucidate the mechanism responsible for the antioxidant activity of pravastatin, and describes relationship between a scavenger effect of pravastatin and the improvement of vascular reactivity.

Background and Purpose: This study investigates the effect of pravastatin on blood pressure, cardiovascular remodelling and impaired endothelial function induced as early signs of cardiovascular disease in young spontaneously hypertensive rats (SHR)., Experimental Approach: Eight-week-old SHR were treated for 4 weeks with pravastatin (20 mg kg(-1) day(-1)). Systolic blood pressure was measured periodically during the study using the tail-cuff method. At the end of the study, the left ventricular weight /body weight ratio was used as an index of left ventricular hypertrophy (LVH). Vascular function, superoxide (O(2)(-*)) production and structure were studied in aortic rings. Lipid peroxidation was measured in plasma (thiobarbituric acid reactive substances assay)., Key Results: Systolic blood pressure was lower in treated SHR than in control SHR, at the end of the study (171 +/- 1 vs. 159 +/- 2 mmHg, P < 0.05), and LVH was significantly reduced by pravastatin (2.7 +/- 0.02 vs. 2.5 +/- 0.01 mg g(-1), P < 0.05). Vascular responses to sodium nitroprusside and phenylephrine were similar in both groups; nevertheless, the relaxation response to acetylcholine was higher in the treated rats (45.6 +/- 2.6 vs. 58.1 +/- 3.2 %, P < 0.05). Vascular O(2)(-*) and plasma thiobarbituric acid reactive substances were reduced by pravastatin treatment, and urinary nitrites was elevated. Finally aortic wall became thinner after pravastatin treatment., Conclusions and Implications: Chronic treatment with pravastatin attenuated the increase of systolic blood pressure in SHR, prevented early LVH and improved vascular structure and function. These effects were accompanied by decreased measures of oxidative stress and improvements in NO production.