Atorvastatin restores endothelial function in normocholesterolemic smokers independent of changes in low-density lipoprotein

Cigarette smoking impairs endothelial function. Hydroxymethylglutaryl (HMG) CoA reductase inhibitors (statins) may favorably affect endothelial function via nonlipid mechanisms. We tested the hypothesis that statins would improve endothelial function independent of changes in lipids in cigarette smokers. Twenty normocholesterolemic cigarette smokers and 20 matched healthy control subjects were randomized to atorvastatin 40 mg daily or placebo for 4 weeks, washed out for 4 weeks, and then crossed-over to the other treatment. Baseline low-density lipoprotein (LDL) levels were similar in smokers and healthy subjects, 103+/-22 versus 95+/-27 mg/dL, respectively (P=NS) and were reduced similarly in smokers and control subjects by atorvastatin, to 55+/-30 and 58+/-20 mg/dL, respectively (P=NS). Vascular ultrasonography was used to determine brachial artery, flow-mediated, endothelium-dependent, and nitroglycerin-mediated, endothelium-independent vasodilation. To elucidate potential molecular mechanisms that may account for changes in endothelial function, skin biopsy specimens were assayed for eNOS mRNA, eNOS activity, and nitrotyrosine. Endothelium-dependent vasodilation was less in smokers than nonsmoking control subjects during placebo treatment, 8.0+/-0.6% versus 12.1+/-1.1%, (P=0.003). Atorvastatin increased endothelium-dependent vasodilation in smokers to 10.5+/-1.3% (P=0.017 versus placebo) but did not change endothelium-dependent vasodilation in control subjects (to 11.0+/-0.8%, P=NS). Endothelium-independent vasodilation did not differ between groups during placebo treatment and was not significantly affected by atorvastatin. Multivariate analysis did not demonstrate any association between baseline lipid levels or the change in lipid levels and endothelium-dependent vasodilation. Cutaneous nitrotyrosine levels and skin microvessel eNOS mRNA, but not ENOS activity, were increased in smokers compared with controls but unaffected by atorvastatin treatment. Atorvastatin restores endothelium-dependent vasodilation in normocholesterolemic cigarette smokers independent of changes in lipids. These results are consistent with a lipid-independent vascular benefit of statins but could not be explained by changes in eNOS message and tissue oxidative stress. These findings implicate a potential role for statin therapy to restore endothelial function and thereby investigate vascular disease in cigarette smokers.     

Tetrahydrobiopterin restores diastolic function and attenuates superoxide production in ovariectomized mRen2.Lewis rats

After oophorectomy, mRen2.Lewis rats exhibit diastolic dysfunction associated with elevated superoxide, increased cardiac neuronal nitric oxide synthase (nNOS) expression, and diminished myocardial tetrahydrobiopterin (BH?) content, effects that are attenuated with selective nNOS inhibition. BH? is an essential cofactor of nNOS catalytic activity leading to nitric oxide production. Therefore, we assessed the effect of 4 wk BH? supplementation on diastolic function and left ventricular (LV) remodeling in oophorectomized mRen2.Lewis rats compared with sham-operated controls. Female mRen2.Lewis rats underwent either bilateral ovariectomy (OVX) (n = 19) or sham operation (n = 13) at 4 wk of age. Beginning at 11 wk of age, OVX rats were randomized to receive either BH? (10 mg/kg · d) or saline, whereas the sham rats received saline via sc mini-pumps. Loss of ovarian hormones reduced cardiac BH? when compared with control hearts; this was associated with impaired myocardial relaxation, augmented filling pressures, increased collagen deposition, and thickened LV walls. Additionally, superoxide production increased and nitric oxide decreased in hearts from OVX compared with sham rats. Chronic BH? supplementation after OVX improved diastolic function and attenuated LV remodeling while restoring myocardial nitric oxide release and preventing reactive oxygen species generation. These data indicate that BH? supplementation protects against the adverse effects of ovarian hormonal loss on diastolic function and cardiac structure in mRen2.Lewis rats by restoring myocardial NO release and mitigating myocardial O?? generation. Whether BH? supplementation is a therapeutic option for the management of diastolic dysfunction in postmenopausal women will require direct testing in humans.     

Terminalia arjuna reverses impaired endothelial function in chronic smokers

BACKGROUND: Smoking, largely through increased oxidative stress, causes endothelial dysfunction which is an early key event in atherosclerosis. Smoking cessation and antioxidant vitamin therapy are shown to have beneficial role by restoring altered endothelial physiology. The present study was aimed to determine whether Terminalia arjuna, an Indian medicinal plant with potent antioxidant constituents, would improve endothelial dysfunction in smokers. METHODS AND RESULTS: Eighteen healthy male smokers (age 28.16+/-9.45 years) and equal number of age-matched non-smoker controls participated in the study. The baseline brachial artery reactivity studies were performed using high frequency ultrasound according to standard protocol under identical conditions to determine endothelium-dependent, flow-mediated dilation and endothelium-independent nitroglycerine-mediated dilation. The two groups were matched regarding age, body mass index, blood pressure, serum cholesterol, mean resting vessel diameters and post-occlusion flow velocities (all p=NS). While flow-mediated dilation was significantly impaired amongst smokers compared to controls (4.71+/-2.22 v. 11.75+/-5.94%, p <0.005), the nitroglycerine-mediated dilation was similar in the two groups (20.35+/-3.89 v. 19.68+/-3.74%, p=NS). Subsequently the smokers were given Terminalia arjuna (500 mg q8h) or matching placebo randomly in a double blind cross-over design for two weeks each, followed by repetition of brachial artery reactivity studies to determine various parameters including flow-mediated dilation after each period. There was no significant difference as regards vessel diameter and flow velocities between the two therapies. However, the flow-mediated dilation showed significant improvement from baseline values after Terrminalia arjuna therapy but not with placebo (9.31+/-3.74 v. 5.17+/-2.42%, p <0.005). CONCLUSIONS: Smokers have impaired endothelium-dependent but normal endothelium-independent vasodilation as determined by brachial artery reactivity studies. Further, Terrminalia arjuna therapy for two weeks leads to significant regression of this endothelial abnormality amongst smokers.     

Cilostazol activates AMP-activated protein kinase and restores endothelial function in diabetes

BACKGROUND: Endothelial dysfunction plays a key role in atherogenesis. We investigated whether AMP-activated protein kinase (AMPK) activity is a downstream mediator of the beneficial effects of cilostazol on vascular endothelial cells and whether cilostazol might reverse endothelial dysfunction in diabetic rats. METHODS AND RESULTS: Treatment of human umbilical vein endothelial cells (HUVECs) with cilostazol resulted in time-dependent activation of AMPK, as monitored by phosphorylation of AMPK and its down-stream target, acetyl-CoA carboxylase (ACC). Activation of AMPK by cilostazol was through signaling pathway independent of cyclic AMP and caused phosphorylation of endothelial nitric oxide synthase (eNOS), leading to increased production of nitric oxide (NO), while inhibiting cytokine-induced nuclear factor-kappaB (NF-kappaB) activation, leading to suppression of VCAM-1 gene expression. Significantly reduced eNOS activity and NO production in response to cilostazol and attenuation of cilostazol-induced inhibition of NF-kappaB activation were observed in cells treated with AMPK siRNA. We also demonstrated that administration of cilostazol to diabetic rats significantly restored endothelium-dependent vasodilation. Furthermore, treatment of diabetic rats with cilostazol increased tetrahydrobiopterin (BH4) levels in the aorta. Thus, recovery of BH4 following administration of cilostazol might also contribute to restoration of endothelial function in diabetic rats. CONCLUSIONS: Our findings suggest that the beneficial effects of cilostazol on endothelial function may be due to AMPK activation. Restoration of endothelial dysfunction in diabetic rats by cilostazol is at least partly attributed to amelioration of biopterin metabolism in the aorta.     

Early statin therapy restores endothelial function in children with familial hypercholesterolemia

OBJECTIVES: This study was designed to determine whether simvastatin improves endothelial function in children with familial hypercholesterolemia (FH). BACKGROUND: Endothelial function measured by flow-mediated dilation of the brachial artery (FMD) is used as a surrogate marker of cardiovascular disease (CVD). Adult studies have shown that statins reverse endothelial dysfunction and therefore reduce the risk for future CVD. METHODS: The study included 50 children with FH (9 to 18 years) and 19 healthy, non-FH controls. Children with FH were randomized to receive simvastatin or placebo for 28 weeks. The FMD was performed at baseline and at 28 weeks of treatment. RESULTS: At baseline, FMD was impaired in children with FH versus non-FH controls (p < 0.024). In the simvastatin FH group, FMD improved significantly, whereas the FMD remained unaltered in the placebo FH group throughout the study period (absolute increase 3.9% +/- 4.3% vs. 1.2% +/- 3.9%, p < 0.05). In the simvastatin FH group, FMD increased to a level similar to the non-FH controls (15.6% +/- 6.8% vs. 15.5% +/- 5.4%, p = 0.958). Upon treatment, the simvastatin FH group showed significant absolute reductions of total cholesterol (TC) (-2.16 +/- 1.04 mmol/l, 30.1%) and low-density lipoprotein cholesterol (LDL-C) (-2.13 +/- 0.99 mmol/l, 39.8%). The absolute change of FMD after 28 weeks of therapy was inversely correlated to changes of TC (r = -0.31, p < 0.05) and LDL-C (r = -0.31, p < 0.05). CONCLUSIONS: Our data show significant improvement of endothelial dysfunction towards normal levels after short-term simvastatin therapy in children with FH. These results emphasize the relevance of statin therapy in patients with FH at an early stage, when the atherosclerotic process is still reversible.     

Decrease of vascular endothelial growth factor in macrophages from long-term smokers.

Vascular endothelial growth factor (VEGF), a survival factor for endothelial cells and a promoter of angiogenesis, is reportedly expressed in alveolar macrophages (AMs). To investigate whether long-term smoking with age affects VEGF expression in AMs, bronchoalveolar lavage (BAL) was performed on 18 young and 23 older volunteers with various smoking histories. The expressions of VEGF and its functional receptor, fms-like tyrosine kinase (Flt)-1, were quantified in AMs by real-time RT-PCR and, further, the level of VEGF in BAL fluid was determined by ELISA. VEGF mRNA in AMs demonstrated a 1.8-fold reduction in current smokers compared with nonsmokers in older subjects and, furthermore, a 1.5-fold downregulation in those with emphysema, although there was no difference between current smokers and nonsmokers among the young subjects. The downregulation in total VEGF mRNA was supported by the substantial reduction of VEGF121 and VEGF165 isoforms. However, in contrast, Flt-1 mRNA did not differ within the older groups, whereas it was upregulated in young current smokers compared with age-matched nonsmokers. VEGF in BAL fluid is significantly decreased in current smokers compared with nonsmokers, regardless of their age. In conclusion, these data imply that the biological availability of vascular endothelial growth factor in alveolar macrophages is impaired in older current smokers with long-term smoking histories.     

Pioglitazone restores endothelial function in patients with type 2 diabetes treated with insulin

The primary aim of this study was to evaluate the effect of pioglitazone on endothelial function, as assessed by flow-mediated dilatation (FMD) nitroglycerine-induced dilatation (NID) in patients with type 2 diabetes mellitus treated with insulin. A randomized double-blind placebo-controlled trial involved 20 patients with insulin-treated type 2 diabetes. Patients received either pioglitazone 30 mg or placebo for 4 months. FMD, NID, and HbA1c were measured before and after 4 months of treatment. HbA1c decreased from 10.0 (+/- 2.3) to 8.4 (+/- 2.0) in the pioglitazone group, a statistically significant improvement in glycemic control (p = 0.018). HbA1c was unchanged in the placebo group (p = 0.477). Endothelial function as assessed by FMD significantly improved from 10.1 (+/- 4.0)% to 14.6 (+/- 6.2)% in the pioglitazone group (p = 0.036) as compared to the placebo group (p = 0.705). There was a trend towards improvement in the NID in the pioglitazone group (from 13.3 +/- 8.0% to 18.9 +/- 5.4%; p = 0.056). In insulin-treated patients with type 2 diabetes, the addition of pioglitazone improves endothelial function, as measured by FMD. Addition of pioglitazone to insulin in type 2 diabetes patients may favorably impact vascular function in diabetes, even after many years of insulin resistance and hyperglycemia.     

青年长期吸烟者血管内皮依赖性舒张功能的改变

目的:探讨青年长期吸烟血管内皮依赖性舒张功能的改变。方法:测定20例长期吸烟青年及15例正常对照者血流介导的和硝酸甘油介导的肱动脉内径改变。结果:两组肱动脉内径基础值(3.75±0 61mm:3.81±0.55mm)及硝酸甘油介导的肱动脉舒张[(22.13±7.65)％:(23.45±8.21)％]无显著差异(P>0.05),而血流介导的血管扩张存在显著差异.为[(3.61±2.90)％:(8.32±4.75)％]、P<0.01。单因素相关分析表明,肱动脉内皮依赖件舒张与吸烟量呈显著负相关(r=0.523.P<0.001).结论:青年长期吸烟者血管内皮依赖性舒张功能明显受损,受损程度与吸烟量有关。     

Effect of green tea consumption on endothelial function and circulating endothelial progenitor cells in chronic smokers.

BACKGROUND: The present study was designed to investigate the effect and relationship of endothelial function and endothelial progenitor cells (EPCs) by green tea consumption in chronic smokers. The numbers of circulating EPCs have an inverse correlation with chronic smoking and endothelial dysfunction. Green tea catechin improved endothelial dysfunction in chronic smokers. METHOD AND RESULTS: In 20 young healthy smokers, endothelial functions, defined by flow-mediated endothelium dependent vasodilation (FMD) of the brachial artery via ultrasound as well as the number of EPCs isolated from peripheral blood, were determined at baseline and at 2 weeks after green tea consumption (8 g/day). Circulating EPCs were quantified by flow cytometry as CD45lowCD34+KDR2+ cells and by acyl-low-density lipoprotein and fluorescein isotiocyanate-lectin double positive cells after culture for 7 days. Clinical characteristics and laboratory findings were not significantly different between the baseline and at 2 weeks after green tea intake. EPC levels were inversely correlated with the number of cigarettes smoked. Circulating EPCs by flow cytometry (78.6+/-72.6 vs 156.1+/-135.8 /ml, p<0.001) and cultured EPCs (118.2+/-35.7 vs 169.31+/-58.3/10 field, p<0.001) increased rapidly at 2 weeks after green tea consumption. FMD was significantly improved after 2 weeks (7.2+/-2.8 vs 9.3+/-2.4, p<0.001). The FMD correlated with EPC counts (r=0.67, p=0.003) before treatment and after 2 weeks (r=0.60, p=0.013). CONCLUSIONS: A short-term administration of green tea consumption induces a rapid improvement of EPC levels and FMD. Green tea consumption may be effective to prevent future cardiovascular events in chronic smokers.     

Soluble vascular endothelial growth factor, soluble VEGF receptor Flt-1 and endothelial function in healthy smokers

OBJECTIVE: To relate levels of vascular endothelial growth factor (VEGF) and its soluble receptor, sFlt-1, with endothelial function in healthy smokers. METHODS: Plasma levels of VEGF and sFlt-1 were measured by ELISA in 22 healthy smokers and 22 matched healthy non-smoking controls, and compared to flow- (FMD) and acetylcholine-mediated (AMD) vasodilatation (endothelial-dependent) (EDV) and nitroglycerine-mediated (NMD) vasodilatation (endothelial-independent) of lower extremities were measured with plethysmography. RESULTS: Smokers and controls had similar plasma VEGF levels, but sFlt-1 levels were lower in smokers than in controls (p<0.01). AMD was lower in smokers compared to controls (p<0.05), but FMD and NMD levels were similar. Smokers and controls with high AMD (>12 ml/100 ml tissue/min) had significantly lower plasma VEGF levels (p<0.001). An inverse correlation was found in both groups, between VEGF and AMD (smokers: r=-0.6, p<0.01; controls: r=-0.71, p<0.005) and with FMD (smokers: r=-0.56, p<0.05; controls: r=-0.58, p<0.005). There were no significant correlations between sFlt-1 with VEGF levels or endothelial-dependent dilatation. CONCLUSION: In conclusion, healthy smokers demonstrate abnormal AMD, and an inverse correlation between plasma VEGF levels (but not sFlt-1) with indices of endothelial dysfunction (FMD and AMD) exists. VEGF, and not sFlt-1, may be related to the pathogenesis of endothelial dysfunction in healthy smoking individuals.     

Tetrahydrobiopterin improves coronary endothelial function, but does not prevent coronary spasm in patients with vasospastic angina.

Reduced bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, and the resulting decrease in NO in the coronary circulation may be involved in the pathogenesis of coronary spasm. The present study investigated the effects of BH4 on the vascular response to acetylcholine (ACh) in 28 patients with vasospastic angina (VA) using quantitative angiography. After recording the vascular responses to ACh (3 and 30 microg/min), either BH4 (1 mg/min) or saline was infused into the coronary artery for 2 min before and during a subsequent infusion of ACh. With the 3 microg/min dose of ACh, BH4 attenuated the ACh-induced decrease in coronary diameter in both the nonspastic segments (-1.1 +/- 2.2% ACh vs 6.0 +/- 2.8% ACh+BH4) and spastic segments (-6.3 +/- 2.7% ACh vs 2.9 +/- 2.7% ACh+BH4), but did not influence the ACh-induced coronary spasm at 30 microg/min (-57.3 +/-2.4% ACh vs -55.3 +/- 2.4% ACh+BH4). In the control patients, saline did not influence either the spastic or nonspastic vasoconstrictor responses to ACh. Acute administration of BH4 improves coronary endothelial function, but does not prevent coronary spasm in patients with VA.