Beneficial effects of cholesterol-lowering therapy on the coronary endothelium in patients with coronary artery disease

Repeated thermal therapy improves impaired vascular endothelial function in patients with coronary risk factors

OBJECTIVES

We sought to determine whether sauna therapy, a thermal vasodilation therapy, improves endothelial function in patients with coronary risk factors such as hypercholesterolemia, hypertension, diabetes mellitus and smoking.

BACKGROUND

Exposure to heat is widely used as a traditional therapy in many different cultures. We have recently found that repeated sauna therapy improves endothelial and cardiac function in patients with chronic heart failure.

METHODS

Twenty-five men with at least one coronary risk factor (risk group: 38 +/- 7 years) and 10 healthy men without coronary risk factors (control group: 35 +/- 8 years) were enrolled. Patients in the risk group were treated with a 60 degrees C far infrared-ray dry sauna bath for 15 min and then kept in a bed covered with blankets for 30 min once a day for two weeks. To assess endothelial function, brachial artery diameter was measured at rest, during reactive hyperemia (flow-mediated endothelium-dependent dilation [%FMD]), again at rest and after sublingual nitroglycerin administration (endothelium-independent vasodilation [%NTG]) using high-resolution ultrasound.

RESULTS

The %FMD was significantly impaired in the risk group compared with the control group (4.0 +/- 1.7% vs. 8.2 +/- 2.7%, p < 0.0001), while %NTG was similar (18.7 +/- 4.2% vs. 20.4 +/- 5.1%). Two weeks of sauna therapy significantly improved %FMD in the risk group (4.0 +/- 1.7% to 5.8 +/- 1.3%, p < 0.001). In contrast, %NTG did not change after two weeks of sauna therapy (18.7 +/- 4.2% to 18.1 +/- 4.1%).

CONCLUSIONS

Repeated sauna treatment improves impaired vascular endothelial function in the setting of coronary risk factors, suggesting a therapeutic role for sauna treatment in patients with risk factors for atherosclerosis.

HMG-CoA reductase inhibitors: Is the endothelium the main target?

Endothelial dysfunction is an early event in atherosclerosis and could be considered a response to the injury induced by major risk factors. There is evidence that endothelial dysfunction is intimately involved in the onset and the progression of cardiovascular disease through abnormalities in the production, release or degradation of endothelium-derived factors, mainly nitric oxide and endothelin 1. Several reports have shown that drugs of the statin class could have multiple beneficial effects related to endothelium-mediated vasoactive, antithrombotic, antiproliferative and anti-inflammatory actions. Thus, the question arises of whether endothelial cells are the main target of statin therapy, in the setting of both hypercholesterolemia and normocholesterolemia. Experimental and clinical studies are reported that could support this hypothesis.

Statins in the 21st century: end of the simple story?

The development of the HMG-CoA reductase inhibitors (the statins) has lead to important advances in the management of cardiovascular disease. There have several landmark mortality and morbidity clinical trials with the statins. The 4S (Scandinavian Simvastatin Survival Study) was the first large-scale randomised cholesterol-lowering trial to show a decrease in mortality. In patients with coronary heart disease and relatively high cholesterol, simvastatin decreased mortality, hospital stays, the risk of undergoing myocardial re-vascularisation, stroke and transient ischaemic attack. The CARE (Cholesterol and Recurrent Events) trial showed that lowering average cholesterol levels after myocardial infarction with pravastatin reduced a composite primary end point of coronary mortality and myocardial infarction, coronary bypass surgery, angioplasty and strokes. The LIPID (Long-term Intervention with Pravastatin in Ischaaemic Disease) study showed that lowering average cholesterol levels after previous myocardial infarction or unstable angina reduced mortality. WOSCOPS (The West of Scotland Coronary Prevention Study) was the first trial to demonstrate the benefit of pravastatin, as primary prevention for cardiovascular disease, in men with high cholesterol levels. AFCAPS/Tex CAPS (The Air Force/Texas Coronary Atherosclerosis Prevention Study) showed that the benefits of lowering cholesterol levels were also evident in healthy men and women who initially had average cholesterol levels. Rather surprisingly the reductions in mortality and morbidity with statins are only associated with small improvements in coronary angiographic findings. A preliminary study indicated than lovastatin prevented restenosis, but larger and better-controlled studies indicate that the statins do not have beneficial effects in restenosis. Effects other than lipid-lowering or as a consequence of their lipid-lowering may contribute to the beneficial effects of statins. These effects include improvement in vascular endothelial function, cardiac remodelling, changes in blood rheology, anti-oxidant, anti-inflammatory and anti-hypertensive actions.

Antiinflammatory and antiarteriosclerotic actions of HMG-CoA reductase inhibitors in a rat model of chronic inhibition of nitric oxide synthesis

Recent studies suggest that some of the beneficial effects of 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) may be due to their cholesterol-lowering independent effects on the blood vessels. Chronic inhibition of endothelial nitric oxide (NO) synthesis by oral administration of N(omega)-nitro-L-arginine methyl ester (L-NAME) to rats induces early vascular inflammation as well as subsequent arteriosclerosis. The aim of the study is to test whether treatment with statins attenuates such arteriosclerotic changes through their cholesterol-lowering independent effects. We investigated the effect of statins (pravastatin and cerivastatin) on the arteriosclerotic changes in the rat model. We found that treatment with statins did not affect serum lipid levels but markedly inhibited the L-NAME-induced vascular inflammation and arteriosclerosis. Treatment with statins augmented endothelial NO synthase activity in L-NAME-treated rats. We also found the L-NAME induced increase in Rho membrane translocation in hearts and its prevention by statins. Such vasculoprotective effects of statins were suppressed by the higher dose of L-NAME. In summary, in this study, we found that statins such as pravastatin and cerivastatin inhibited vascular inflammation and arteriosclerosis through their lipid-lowering independent actions in this model. Such antiarteriosclerotic effects may involve the increase in endothelial NO synthase activity and the inhibition of Rho activity.

A new HMG-CoA reductase inhibitor, rosuvastatin, exerts anti-inflammatory effects on the microvascular endothelium: the role of mevalonic acid

Recent studies have reported that hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have vasculoprotective effects independent of their lipid-lowering properties, including anti-inflammatory actions. We used intravital microscopy of the rat mesenteric microvasculature to examine the effects of rosuvastatin, a new HMG-CoA reductase inhibitor, on leukocyte-endothelium interactions induced by thrombin. Intraperitoneal administration of 0.5 and 1.25 mg kg(-1) rosuvastatin 18 h prior to the study, significantly and dose-dependently attenuated leukocyte rolling, adherence, and transmigration in the rat mesenteric microvasculature superfused with 0.5 u ml(-1) thrombin. This protective effect of rosuvastatin was reversed by intraperitoneal injection of 25 mg kg(-1) mevalonic acid 18 h before the study. Immunohistochemical detection of the endothelial cell adhesion molecule P-selectin showed a 70% decrease in endothelial cell surface expression of P-selectin in thrombin-stimulated rats given 1.25 mg kg(-1) rosuvastatin. In addition, rosuvastatin enhanced release of nitric oxide (NO) from the vascular endothelium as measured directly in rat aortic segments. Moreover, rosuvastatin failed to attenuate leukocyte-endothelium interactions in peri-intestinal venules of eNOS(-/-) mice. These data indicate that rosuvastatin exerts important anti-inflammatory effects via inhibition of endothelial cell adhesion molecule expression, and that this protective action of rosuvastatin requires release of nitric oxide by the vascular endothelium. These data also demonstrate that the mechanism of the non-lipid lowering actions of HMG-CoA reductase inhibitors in vivo may be due to reduced formation or availability of mevalonic acid within endothelial cells.

Effectiveness of statins in acute coronary syndromes

Over the past several years, results of clinical trials of lipid lowering have increased our understanding of the pathophysiology of coronary atherosclerosis and ischemia. Evidence is accumulating that cholesterol lowering has potential anti-ischemic effects and may have immediate consequences that have a favorable impact on coronary events, possibly even acute coronary syndromes. Yet, less than one half of all patients hospitalized for acute coronary syndromes have their cardiovascular risks appropriately modified. The results of recent statin trials provide impetus for the implementation of aggressive risk-reduction strategies in patients with coronary atherosclerosis, including those with recent acute coronary syndromes. Prevention is now a viable therapeutic goal.

Flow-mediated vasodilation is not impaired when HDL-cholesterol is lowered by substituting carbohydrates for monounsaturated fat

Low-fat diets, in which carbohydrates replace some of the fat, decrease serum cholesterol. This decrease is due to decreases in LDL-cholesterol but in part to possibly harmful decreases in HDL-cholesterol. High-oil diets, in which oils rich in monounsaturated fat replace some of the saturated fat, decrease serum cholesterol mainly through LDL-cholesterol. We used these two diets to investigate whether a change in HDL-cholesterol would change flow-mediated vasodilation, a marker of endothelial function. We fed thirty-two healthy volunteers two controlled diets in a weeks' randomised cross-over design to eliminate variation in changes due to differences between subjects. The low-fat diet contained 59.7 % energy (en%) as carbohydrates and 25.7 en% as fat (7.8 en% as monounsaturates); the oil-rich diet contained 37.8 en% as carbohydrates and 44.4 en% as fat (19.3 en% as monounsaturates). Average (sd) serum HDL-cholesterol after the low-fat diet was 0.21 (sd 0.12) mmol/l (8.1 mg/dl) lower than after the oil-rich diet. Serum triacylglycerols were 0.22 (sd 0.28) mmol/l (19.5 mg/dl) higher after the low-fat diet than after the oil-rich diet. Serum LDL and homocysteine concentrations remained stable. Flow-mediated vasodilation was 4.8 (SD 2.9) after the low-fat diet and 4.1 (SD 2.7) after the oil-rich diet (difference 0.7 %; 95 % CI -0.6, 1.9). Thus, although the low-fat diet produced a lower HDL-cholesterol than the high-oil diet, flow-mediated vasodilation, an early marker of cardiovascular disease, was not impaired.

Effects of low-density lipoprotein apheresis on coronary and carotid atherosclerosis and diabetic scleredema in patients with severe hypercholesterolemia

Correlations between serum cholesterol levels and progression of coronary and peripheral atherosclerosis have been found in many recent studies. It has also been demonstrated that aggressive cholesterol-lowering therapy with low-density lipoprotein (LDL) apheresis, a method of LDL elimination by extracorporeal circulation, is effective not only for coronary artery disease, but also for systemic circulatory disturbance in severe hypercholesterolemic patients with familial hypercholesterolemia (FH) in particular. We found that LDL apheresis treatment with medical therapy improved coronary atherosclerotic lesions, based on coronary angiography evaluation and histopathological observation, suppressed progression of early carotid atherosclerotic lesions on annual B-mode ultrasonography, and improved diabetic scleredema in FH patients. This effectiveness of LDL apheresis appears to be due to recovery of vascular endothelial function and improvement of blood rheology. For diseases that are possibly due to circulation disturbance and that are intractable with drugs alone. LDL apheresis may be worth trying, particularly for patients complicated by hyperlipemia.

Current topics on low-density lipoprotein apheresis

The prognosis of patients suffering from severe hyperlipidemia, sometimes combined with elevated lipoprotein (a) (Lp[a]) levels, and coronary heart disease (CHD) refractory to diet and lipid-lowering drugs is poor. For such patients, regular treatment with low-density lipoprotein (LDL) apheresis is the therapeutic option. Today, there are four different LDL-apheresis systems available: immunoadsorption, heparin-induced extracorporeal LDL/fibrinogen precipitation, dextran sulfate LDL-adsorption, and LDL-hemoperfusion. Despite substantial progress in diagnostics, drug therapy, and cardiosurgical procedures, atherosclerosis with myocardial infarction, stroke, and peripheral cellular disease still maintains its position at the top of morbidity and mortality statistics in industrialized nations. Established risk factors widely accepted are smoking, arterial hypertension, diabetes mellitus, and central obesity. Furthermore, there is a strong correlation between hyperlipidemia and atherosclerosis. Besides the elimination of other risk factors, in severe hyperlipidemia (HLP) therapeutic strategies should focus on a drastic reduction of serum lipoproteins. Despite maximum conventional therapy with a combination of different kinds of lipid-lowering drugs, however, sometimes the goal of therapy cannot be reached. Mostly, the prognosis of patients suffering from severe HLP, sometimes combined with elevated Lp(a) levels and CHD refractory to diet and lipid-lowering drugs is poor. Hence, in such patients, treatment with LDL-apheresis can be useful. Regarding the different LDL-apheresis systems used, there were no significant differences with respect to the clinical outcome or concerning total cholesterol, LDL, high-density lipoprotein, or triglyceride concentrations. With respect to elevated Lp(a) levels, however, the immunoadsorption method seems to be the most effective. The published data clearly demonstrate that treatment with LDL-apheresis in patients suffering from severe hyperlipidemia refractory to maximum conservative therapy is effective and safe in long-term application.

Sustained long-term improvement of arterial endothelial function in heterozygous familial hypercholesterolemia patients treated with simvastatin

Patients with heterozygous familial hypercholesterolemia (hFH) are at very high risk for premature coronary heart disease. In the last decade, treatment with statins has reduced cardiovascular mortality in these patients. The aim of this study was to analyze arterial endothelial function assessed as flow-mediated dilatation (FMD) and soluble E-selectin (sE-selectin) levels in patients with hFH under a long-term lipid-lowering treatment. Twenty-five patients who completed the study received a dose of simvastatin to achieve a treatment goal of at least 30% reduction in serum low-density lipoprotein (LDL)-cholesterol (LDL-C) for 52 weeks. Functional and biochemical measurements were taken at entry, and at week 12 and 52 of treatment. FMD was measured by vascular ultrasound of the brachial artery. sE-selectin, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 were determined by enzyme linked immunosorbent assay (ELISA). LDL-C levels were significantly reduced by treatment at week 12 and maintained at week 52 (reduction vs. baseline, 44+/-12 and 43+/-11%, respectively, P<0.0001). A significant improvement in endothelial function, measured as FMD (baseline, 4.7+/-6.2%; 12 weeks, 12.3+/-5.9%; 52 weeks, 9.7+/-4.7%; P<0.005) and a reduction in sE-selectin levels (baseline, 16.2+/-3.4 ng/ml; 12 weeks, 11.0+/-3.2 ng/ml; 52 weeks, 12.3+/-4.2 ng/ml; P<0.01) were observed. Endothelial-independent relaxation induced by nitroglycerin was not modified during the study. Our results indicate that a long-term treatment with simvastatin produced a sustained beneficial effect in endothelial function in hFH patients.

3-hydroxy-3-methylglutaryl coenzyme a reductase inhibition prevents endothelial NO synthase downregulation by atherogenic levels of native LDLs: balance between transcriptional and posttranscriptional regulation

Atherogenic levels of native low density lipoproteins (nLDLs) decrease the bioavailability of endothelium-derived NO and downregulate endothelial NO synthase (eNOS) expression in cultured human endothelial cells. Here, we show that simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, within the therapeutic range (0.01 to 1 micromol/L) prevented the downregulation of eNOS mRNA and protein promoted by nLDL (180 mg cholesterol/dL, 48 hours) in human umbilical vein endothelial cells. This effect of simvastatin was completely reversed by mevalonate, the product of the reaction, and to a lesser extent by farnesol and geranyl geraniol. Simvastatin significantly stabilized eNOS mRNA in cells treated with nLDL during 48 hours (eNOS mRNA half-life approximately 11 hours in controls versus >24 hours in nLDL per 0.1 micromol/L simvastatin-treated cells). The downregulation of eNOS by nLDL was abrogated by cycloheximide, an inhibitor of protein synthesis, and by N-acetyl-leucyl-leucyl-norleucinal, a protease inhibitor that reduces the catabolism of sterol regulatory element binding proteins. Sterol deprivation increased the downregulation produced by nLDL on eNOS and sterol regulatory element binding protein-2 expression levels. However, no differential modulation of the retardation bands corresponding to the putative sterol-responsive element present in the eNOS promoter was detected by electrophoretic mobility shift assay. Our results suggest that nLDL promote eNOS downregulation operating at a transcriptional level, whereas simvastatin prevents such an effect through a posttranscriptional mechanism.

Pathophysiology of vascular endothelium and circulating platelets: implications for coronary revascularisation and treatment

Constant vasodilatation, inhibition of platelet and leukocyte adhesion, and local thrombolysis are the mechanisms through which an intact endothelial layer exerts its protective action on coronary circulation. A loss in these features is not only the first step in the development of atherosclerosis, but also a potent trigger for complications after revascularisation procedures. Percutaneous coronary interventions, particularly in the course of stenting, induce endothelial injury that can last up to months after the procedure. On the other hand, the preservation of endothelial function appears the best feature of arterial versus venous grafts after coronary bypass surgery. An early diagnosis either by invasive or non-invasive techniques has important implications for prognosis, and endothelial dysfunction can be effectively counteracted by medical treatment (ACE inhibitors, statins). Activated circulating platelets are present in the course of coronary artery disease, increasing the risk of thrombotic occlusion and/or plaque regrowth, after both percutaneous and surgical revascularisation. New antiplatelet agents are under development to reduce endothelium-platelet interaction. On the basis of the latest studies, coronary revascularisation should be integrated in a more complete treatment, which would take into account the complex processes involving the underlying atherosclerotic plaque.

The effects of converting from simvastatin to atorvastatin on plasminogen activator inhibitor type-1

Plasminogen activator inhibitor type-1 (PAI-1) is an important regulatory component of fibrinolysis and is elevated in the presence of endothelial dysfunction. Endothelial dysfunction and PAI-1 in patients with coronary artery disease (CAD) have been demonstrated to improve following simvastatin therapy. The effect of converting from simvastatin to atorvastatin on PAI-1 has not been reported and may be an additional consideration when making a formulary medication switch. Fourteen adult patients with hypercholesterolemia and CAD who were receiving simvastatin for a minimum of 3 months were randomized to continue on simvastatin or be converted to atorvastatin. Doses were adjusted to achieve or sustain a low-density lipoprotein (LDL) cholesterol of < or = 100 mg/dL. A fasting lipid panel and PAI-1 were obtained at baseline and following 10 weeks of treatment. Mean +/- SD LDL cholesterol at baseline (95.6 +/- 13.8 vs. 87.0 +/- 12.3 dL, p = 0.24) and following 10 weeks of simvastatin or atorvastatin (96.6 +/- 8.9 vs. 87.4 +/- 20.3 mg/dL, p = 0.29) were similar. No differences in PAI-1 were observed at baseline (47.7 +/- 19.3 vs. 64.6 +/- 22.2 ng/mL, p = 0.15) or at 10 weeks (51.1 +/- 32.5 vs. 63.9 +/- 26.9 ng/mL, p = 0.44). These data suggest that the conversion from simvastatin to atorvastatin does not adversely affect PAI-1 plasma concentrations in patients with CAD.

Replacement of dietary saturated fatty acids by trans fatty acids lowers serum HDL cholesterol and impairs endothelial function in healthy men and women

We tested whether trans fatty acids and saturated fatty acids had different effects on flow-mediated vasodilation (FMD), a risk marker of coronary heart disease (CHD). Consumption of trans fatty acids is related to increased risk of CHD, probably through effects on lipoproteins. Trans fatty acids differ from most saturated fatty acids because they decrease serum high-density lipoprotein (HDL) cholesterol, and this may increase the risk of CHD. We fed 29 volunteers 2 controlled diets in a 2x4-week randomized crossover design. The "Trans-diet" contained 9.2 energy percent of trans fatty acids; these were replaced by saturated fatty acids in the "Sat-diet." Mean serum HDL cholesterol after the Trans-diet was 0.39 mmol/L (14.8 mg/dL), or 21% lower than after the Sat-diet (95% CI 0.28 to 0.50 mmol/L). Serum low density lipoprotein and triglyceride concentrations were stable. FMD+SD was 4.4+/-2.3% after the Trans-diet and 6.2+/-3.0% after the Sat-diet (difference -1.8%, 95% CI -3.2 to -0.4). Replacement of dietary saturated fatty acids by trans fatty acids impaired FMD of the brachial artery, which suggests increased risk of CHD. Further studies are needed to test whether the decrease in serum HDL cholesterol caused the impairment of FMD.

Non-lipid effects of statin on hypercholesterolemic patients established to have coronary artery disease who remained hypercholesterolemic while eating a step-II diet

BACKGROUND

Results of clinical trials of statin therapy demonstrate that an improvement in incidence of cardiovascular end points and coronary stenosis can be achieved. The beneficial effects of statins on clinical events may involve nonlipid mechanisms that affect endothelial function, such as inflammatory responses, formation of thrombi, and stabilization of plaque.

OBJECTIVE

To investigate levels of serologic markers, which may be useful surrogates for activity of vascular disease after administration of statin.

METHODS

We administered 20-40 mg simvastatin daily for 14 weeks to 13 patients established to have coronary artery disease who remained hypercholesterolemic during step-II diet therapy.

RESULTS

Administration of simvastatin significantly lowered lipoprotein levels and the low: high-density lipoprotein cholesterol level ratio and apolipoprotein B:A-I level ratio compared with pretreatment values (P < 0.01). Administration of simvastatin significantly lowered plasma levels of matrix metalloproteinase-9 (MMP-9) and monocyte chemoattractant protein-I [33+/-46 and 13+/-19%, respectively (P = 0.027 and 0.020, respectively)]. Furthermore, administration of simvastatin tended to lower plasma levels of plasminogen activator inhibitor type-1 and tumor necrosis factor-alpha [by 20+/-44 and 13+/-29%, respectively (P= 0.066 and 0.110, respectively)]. There were significant inverse correlations between pretreatment levels of MMP-9 and the degree of change in those levels after administration of simvastatin (r = -0.714, P= 0.005). However, there was no significant correlation between levels of lipoprotein and levels of MMP-9, monocyte chemoattractant protein-I, and plasminogen activator inhibitor type-1 during administration of simvastatin.

CONCLUSIONS

Our current data support the hypothesis that nonlipid mechanisms elicited by administration of simvastatin contribute to the decrease in incidence of cardiovascular events and explain the early clinical benefit observed in clinical trials, independent of changes in levels of lipoprotein.

A randomized double-blind placebo-controlled trial of the effect of homocysteine-lowering therapy with folic acid on endothelial function in patients with coronary artery disease

OBJECTIVES

This study was designed to determine the effects of folic acid therapy on endothelial function in patients with coronary artery disease (CAD).

BACKGROUND

Hyperhomocysteinemia, a risk factor for CAD, may cause atherosderosis by oxidative endothelial injury. Folic acid reduces plasma homocysteine, but the effect on adverse vascular events is unknown.

METHODS

In a double-blind placebo-controlled trial, 90 patients (mean age [range] 63 [46 to 79] years, 79 men) with CAD were randomized to either folic acid 5 mg or placebo daily for 12 weeks. Endothelial function was assessed by measuring: 1) flow-mediated endothelium-dependent dilation (EDD) of the brachial artery; 2) combined serum nitrite/nitrate (NOx) concentrations and; 3) plasma von Willebrand factor (vWF) concentration.

RESULTS

At the end of the study, plasma homocysteine was lower in the folic acid group compared with the placebo group (mean [95% confidence interval] 9.3 (8.5 to 10.1) vs. 12.3 [11.3 to 13.4] micromol/l, p < 0.001). Although there were no significant differences in EDD, serum NOx or plasma vWF between the two groups, there was a greater increase in EDD from baseline in the folic acid group compared to placebo (1.2 [0.7 to 1.8] vs. 0.4 [-0.3 to 1.1]%, p = 0.07).

CONCLUSIONS

Folic acid reduced plasma homocysteine and was associated with a trend toward improved endothelial function in patients with CAD. The absence of an unequivocally positive result may have been due to inadequate sample size or chance. This reinforces the need for the results of large randomized controlled trials before the implementation of routine folic acid supplementation.

Simvastatin exerts both anti-inflammatory and cardioprotective effects in apolipoprotein E-deficient mice

BACKGROUND

Simvastatin attenuates ischemia and reperfusion in normocholesterolemic animals by stabilizing endothelial nitric oxide synthase activity and inhibiting neutrophil-mediated injury. Because endothelial dysfunction is a detrimental effect of hypercholesterolemia, we examined whether short-term treatment with simvastatin could inhibit leukocyte-endothelium interaction and attenuate myocardial ischemia-reperfusion injury in apoE-deficient (apoE(-/-)) mice fed a high-cholesterol diet.

METHODS AND RESULTS

We studied leukocyte-endothelium interactions in apoE(-/-) mice fed a normal or a high-cholesterol diet after short-term (ie, 18 hours) simvastatin treatment. We also studied simvastatin treatment in myocardial ischemia-reperfusion injury by subjecting apoE(-/-) mice to 30 minutes of ischemia and 24 hours of reperfusion. ApoE(-/-) mice fed a high-cholesterol diet exhibited higher blood cholesterol levels, which were not affected by short-term simvastatin treatment. However, the increased leukocyte rolling and adherence that occurred in cholesterol-fed apoE(-/-) mice (P<0.001 versus control diet) were significantly attenuated by simvastatin treatment (P<0.01 versus vehicle). Cholesterol-fed apoE(-/-) mice subjected to myocardial ischemia-reperfusion also experienced increased myocardial necrosis (P<0.01 versus control diet), which was significantly attenuated by simvastatin (P<0.01 versus vehicle). Simvastatin therapy also significantly increased vascular nitric oxide production in apoE(-/-) mice.

CONCLUSIONS

Simvastatin attenuates leukocyte-endothelial cell interactions and ameliorates ischemic injury in hypercholesterolemic mice independently of lipid-lowering actions.

Effect of anti-oxidant treatment and cholesterol lowering on resting arterial tone, metabolic vasodilation and endothelial function in the human forearm: a randomized, placebo-controlled study

1. The aim of the present study was to determine whether anti-oxidant therapy with vitamin E and/or cholesterol-lowering therapy with simvastatin would augment resting forearm blood flow (FBF) and metabolic vasodilation in response to exercise and improve endothelial function in young patients with hypercholesterolaemia. 2. Endothelium-dependent and -independent, nitric oxide (NO)-mediated vasodilation have been shown to be impaired in young, otherwise healthy subjects with hypercholesterolaemia. Recent experimental and clinical studies suggest that vascular function may be improved with anti-oxidant or cholesterol- lowering therapy, although these treatments may be synergistic. 3. We compared FBF at rest, in response to isotonic exercise, the endothelium-dependent vasodilator acetylcholine (ACh), the endothelium-independent vasodilator sodium nitroprusside (SNP) and the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) in 26 young, otherwise healthy volunteers (mean (+/-SD) age 29+/-7 years; 14 female, 12 male) with hypercholesterolaemia, before and after 6 months treatment with vitamin E, simvastatin and/or placebo. Treatment was randomized, double-blinded in a 2 x 2 factorial design. Forearm blood flow was measured using venous occlusion plethysmography. 4. Vitamin E therapy increased plasma alpha-tocopherol from 39.5+/-9.6 to 75.7+/-33.8 micromol/L (P < 0.001). Simvastatin reduced total cholesterol from 6.9+/-1.7 to 4.9+/-0.8 mmol/L and low- density lipoprotein (LDL) from 4.8+/-1.7 to 3.0+/-0.7 mmol/L (both P < 0.001), although total and LDL-cholesterol also decreased slightly in the placebo group. Vitamin E increased resting FBF from 2.1+/-0.3 to 2.4+/-0.3 mL/100 mL per min (P = 0.04) and decreased resting forearm vascular resistance from 42.1+/-4.2 to 36.1+/-3.4 units (P = 0.01), but the reduction in resting FBF with L-NMMA was not affected. Vasodilation in response to isotonic exercise, ACh and SNP was similar before and after treatment in the placebo, vitamin E, simvastatin and in the combined vitamin E-simvastatin groups. NG-Monomethyl-L-arginine infusion reduced resting FBF and functional hyperaemia in response to exercise and these responses were not altered by treatment. 5. These data suggest that while vitamin E therapy augments resting FBF and reduces forearm vascular resistance in young hypercholesterolaemic subjects, these effects may not be via NO-dependent pathways. Metabolic vasodilation and responses to the NO-mediated vasodilators ACh and SNP were not favourably affected by anti-oxidant or cholesterol-lowering therapy, either alone or in combination.

Relationship between the angiotensin-converting enzyme genotype and the forearm vasodilator response to estrogen replacement therapy in postmenopausal women

OBJECTIVES

We sought to evaluate the relationship between the angiotensin-converting enzyme (ACE) genotype and the change in forearm vasoreactivity in response to a three-month course of oral estrogen in postmenopausal women.

BACKGROUND

The ACE genotype is a known predictor of the response to an ACE inhibitor drug; however, it is not clear whether it can modify the effect of estrogen replacement therapy (ERT) on endothelial function in postmenopausal women.

METHODS

Fifty-five postmenopausal women received 0.625 mg of conjugated equine estrogen daily for three months. Forearm blood flow (FBF) was measured by strain-gauge plethysmography.

RESULTS

Twenty-one, 25 and 9 patients had the insertion/deletion (ID), II and DD genotypes, respectively. Plasma ACE activity was significantly higher at baseline in patients with either the DD or ID genotype than in those with the II genotype (p < 0.05). A significant decrease in plasma ACE activity with ERT was seen in the ID and II genotypes (p < 0.05), but not in the DD genotype. There were no significant differences in the FBF responses to reactive hyperemia at baseline between the three groups. Estrogen replacement therapy did not alter the FBF response to reactive hyperemia in the DD genotype (4.0 +/- 1.3%), although ERT significantly increased the FBF response in the ID and II genotypes (32.6 +/- 7.5% and 30.6 +/- 6.5%, respectively; p < 0.05). Forearm blood flow after administration of sublingual nitroglycerin did not change over three months in any of the three groups.

CONCLUSIONS

These findings suggest that the effect of ERT in postmenopausal women on forearm endothelial function may be determined in part by the genotype of the ACE gene.

Noninvasive tests of vascular function and structure: why and how to perform them

BACKGROUND

Early atherosclerosis involves the endothelium of many arteries. Information about peripheral arterial anatomy and function derived from vascular imaging studies such as brachial artery reactivity (BAR) and carotid intima media thickness (IMT) may be pertinent to the coronary circulation. The prevention and early treatment of atherosclerosis is gaining more attention, and these tests might be used as indications or perhaps guides to the effectiveness of therapy, but their application in clinical practice has been limited. This review seeks to define the anatomy and pathophysiology underlying these investigations, their methodology, the significance of their findings, and the issues that must be resolved before their application.

METHODS

The literature on BAR and IMT is extensively reviewed, especially in relation to clinical use.

RESULTS

Abnormal flow-mediated dilation is present in atherosclerotic vessels, is associated with cardiovascular risk factors, and may be a marker of preclinical disease. Treatment of known atherosclerotic risk factors has been shown to improve flow-mediated dilation, and some data suggest that vascular responsiveness is related to outcome. Carotid IMT is associated with cardiovascular risk factors, and increased levels can predict myocardial infarction and stroke. Aggressive risk factor management can decrease IMT.

CONCLUSIONS

BAR and IMT are functional and structural markers of the atherosclerotic process. The clinical use of BAR has been limited by varying reproducibility and the influence by exogenous factors, but IMT exhibits less variability. A desirable next step in the development of BAR and IMT as useful clinical tools would be to show an association of improvement in response to treatment with improvement in prognosis.

Prevention of a first myocardial infarction

Coronary heart disease is the leading cause of morbidity and mortality in men and women in the Western world. We now have significant evidence that prevention of the first coronary event using lifestyle and pharmacologic therapies is paramount. Events are caused by inflamed arteries leading to rupture of atherosclerotic plaques that induce potentially occlusive thrombi. Analysis of event reduction trials has revealed that LDL-C lowering is only one part of the therapy needed to stabilize plaque. HMG-Co-A-reductase inhibitors, fibrates, and statins all have differing mechanisms of action that provide not only lipid but also inflammatory, rheologic, and coagulation benefits. Concentration and sizes of lipoprotein subfractions have emerged as important new tools with small dense LDL particles having more atherogenicity, which has led to an increasing use of aggressive combination therapy for prevention of first myocardial infarction. Proper use of lipid-lowering therapies requires knowledge of drug metabolism drug-drug interactions.

Fluvastatin therapy improves microcirculation in patients with hyperlipidaemia

The purpose of this study was to investigate the effect of fluvastatin on the microcirculation of patients with hyperlipidaemia (low-density lipoprotein cholesterol > 160 mg/dL, triglycerides < 350 mg/dl) inadequately controlled by diet. After a dietary run-in of 4 weeks, patients were randomised in a double-blind study to receive fluvastatin 40 mg twice daily (n = 24) or placebo (n = 24) for 12 weeks. The effect on microcirculation was assessed using capillary microscopy and laser Doppler fluxmetry at the nailfold at baseline and at 6 and 12 weeks after initiation of therapy. Capillaroscopy showed that fluvastatin improved microcirculation, i.e. time to peak flow during postocclusive reactive hyperaemia dropped from 19.7 +/- 7.2 s at baseline to 12.3 +/- 9.5 s at week 6 (P < 0.01) and 10.6 +/- 6.5 s at week 12 (P < 0.0001). These results were confirmed using laser Doppler fluxmetry to study microcirculation in thermoregulatory capillaries at the same site. A significant decrease in total and LDL-cholesterol was achieved during fluvastatin therapy. In conclusion, fluvastatin therapy improves microcirculation in nutritive as well as thermoregulatory capillaries in hypercholesterolaemic patients within 6 weeks.

Rapid improvement of nitric oxide bioavailability after lipid-lowering therapy with cerivastatin within two weeks

OBJECTIVES

We investigated whether improvement of endothelial dysfunction in hypercholesterolemia can be achieved with short-term lipid-lowering therapy.

BACKGROUND

Impaired endothelium-dependent vasodilation plays a pivotal role in the pathogenesis of atherosclerosis and acute coronary syndromes.

METHODS

In a randomized, double-blind, placebo-controlled trial, we studied 37 patients (52 +/- 11 yrs) with low density lipoprotein cholesterol > or = 160 mg/dl (196 +/- 44 mg/dl) randomly assigned to either cerivastatin (0.4 mg/d) or placebo. Endothelium-dependent vasodilation of the forearm vasculature was measured by plethysmography and intra-arterial infusion of acetylcholine (ACh 12, 48 microg/min) and endothelium-independent vasodilation by intra-arterial infusion of nitroprusside (3.2, 12.8 microg/min).

RESULTS

Low density lipoprotein cholesterol decreased after two weeks of treatment (cerivastatin -33 +/- 4% vs. placebo + 2 +/- 4%, x +/- SEM, p < 0.001). Endothelium-dependent vasodilation improved after two weeks of therapy with cerivastatin compared with baseline (ACh 12 microg/min: + 22.3 +/- 5.2 vs. + 11.2 +/- 1.9 ml/min/100 ml, p < 0.01; ACh 48 microg/min: +31.2 +/- 6.3 vs. +19.1 +/- 3.1 ml/min/100 ml, p < 0.05). In contrast, changes in forearm blood flow to ACh were similar before and after therapy in the placebo group (ACh 12 microg/min: + 12.9 +/- 3.6 vs. + 9.0 +/- 1.9 ml/min/100 ml, NS; ACh 48 microg/min: +20.7 +/- 3.7 vs. 19.4 +/- 2.9 ml/min/100 ml, NS). Endothelium-dependent vasodilation improved in comparison with placebo (ACh 48 microg/min: +203 +/- 85% [cerivastatin] vs. -26 +/- 71% [placebo], p < 0.05). This improvement in endothelium-dependent vasodilation was no longer observed when the nitric oxide-synthase inhibitor N(G)-monomethyl-L-arginine was coinfused (ACh 48 microg/min + N(G)-monomethyl-L-arginine 4 micromol/min -48 +/- 85% [cerivastatin]).

CONCLUSIONS

Short-term lipid-lowering therapy with cerivastatin can improve endothelial function and NO bioavailability after two weeks in patients with hypercholesterolemia.

Heparin attenuates norepinephrine-induced venoconstriction

Reversal by heparin of norepinephrine-induced constriction of normal hand veins was studied. Venous size was measured using a linear variable differential transformer (LVDT) during infusions of saline, norepinephrine, insulin and norepinephrine, and graded doses of heparin with norepinephrine. Heparin reduced the venoconstrictive effects of norepinephrine (p < 0.01), with the effects beginning at 18.5 nmol/min (0.05 U/min) and reaching a maximum between 185 nmol/min and 1.85 mumol/min (0.5 and 5 U/min). Maximal heparin-induced venorelaxation correlated with the maximal insulin effect within individuals (r = 0.8, p < 0.01) and was unchanged by the addition of insulin. Methylene blue, a non-specific inhibitor of the nitric oxide cGMP cascade, reduced heparin-induced venorelaxation. In conclusion, heparin in either physiologic or pharmacologic concentration attenuated norepinephrine-induced venoconstriction. A common mechanism of venorelaxation by heparin and insulin is not excluded given the correlation and lack of additivity of maximum effects and their inhibition by methylene blue.

Effect of concomitant or very early statin administration on in-hospital mortality and reinfarction in patients with acute myocardial infarction

In a retrospective analysis, 66 patients identified as having received a statin drug within 24 hours of admission for acute myocardial infarction were matched 3:1 with a control group of 198 patients not treated with a statin agent. End points of in-hospital mortality and in-hospital reinfarction were significantly lower in the statin-treated group, pointing to a benefit from very early statin treatment in acute myocardial infarction.

Elderly patients at risk for coronary heart disease or stroke: selecting an ideal product for lipid lowering

Coronary heart disease is an affliction of the elderly: 84% of those who die from the disease are over 65 years of age. In patients over 55 years, the incidence of stroke more than doubles with each decade of life. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, have been shown to lower cholesterol and lipids in both middle-aged and elderly patients in large clinical trials. Some statins have been shown to improve endothelial function and vasodilation and to normalize thrombin formation, which may be among the mechanisms involved in both coronary event and stroke prevention.

The influence of short-term treatment with simvastatin on the inflammatory profile of patients with hypercholesterolaemia

BACKGROUND

Treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors can reduce cardiovascular mortality of patients with atherosclerosis. This effect is probably due not only to a decrease in concentration of cholesterol, but also to non-lipid-involving mechanisms elicited by the action of statin drugs.

OBJECTIVE

To investigate the influence of short-term therapy with simvastatin on markers of inflammation and oxidation processes in patients with hypercholesterolaemia.

DESIGN

We administered 20mg simvastatin daily for 12 weeks to 19 patients with hypercholesterolaemia (250-400 mg/dl). Peripheral blood samples for evaluation of plasma concentrations of thiobarbituric acid reactive substances (malonaldehyde), stable metabolites of nitric oxide (NOx) and interleukin 6 (11-6) were taken before and after the therapy.

RESULTS

Plasma levels of malonaldehyde decreased significantly (from 4.533+/-0.428 versus 3.690+/-0.310 micromol/l, P = 0.04) during the study period. Similarly, there was a significant decrease in the plasma concentrations of NOx (from 33.477+/-4.352 micromol/l versus 25.919+/-2.561 micromol/l, P = 0.02). There were significant positive correlations between concentrations of total cholesterol and NOx in plasma (r = 0.4397, P = 0.008) and of low-density lipoprotein and NOx (r = 0.3987, P = 0.02). The plasma level of interleukin 6 remained unchanged by the intervention (1.837+/-0.200 versus 1.820+/-0.169 pg/ml, P = 0.54).

CONCLUSIONS

Short-term therapy with simvastatin decreases the plasma concentrations of markers of peroxidation of lipids and of stable metabolites of nitric oxide in hypercholesterolaemic patients, but leaves levels of interleukin 6 unaffected.

Cerivastatin prevents tumor necrosis factor-alpha-induced downregulation of endothelial nitric oxide synthase: role of endothelial cytosolic proteins

Cardiovascular disease is accompanied by an impaired endothelium-dependent vasodilatory response. Loss of endothelial nitric oxide synthase (eNOS) expression may contribute to endothelial dysfunction. The aim of the present study was to analyze the effect of cerivastatin, a novel HMG CoA reductase inhibitor, on tumor necrosis factor-alpha (TNF-alpha)-induced downregulation of eNOS protein expression in bovine aortic endothelial cells (BAEC). TNF-alpha (10 ng/ml)- incubated BAEC showed a reduced expression of eNOS protein and decreased eNOS mRNA stabilization. This effect was associated with an increased binding activity of BAEC cytosolic proteins to the 3'-untranslated region (3'UTR) of eNOS mRNA. Cerivastatin prevented TNF-alpha-induced downregulation of eNOS protein expression in a concentration-dependent manner (10(-8) to 10(-5) M). Cerivastatin also prevented the binding of the cytosolic proteins to 3'-UTR of eNOS mRNA and was associated with eNOS mRNA stabilization. The reduced expression of eNOS protein by TNF-alpha was also prevented by coincubation with cycloheximide. In addition cycloheximide inhibited the binding activity of the cytosolic proteins to 3'-UTR of eNOS mRNA, suggesting the inducible character of the mentioned-cytosolic proteins. TNF-alpha stimulated the translocation of nuclear factor-kappaB (NF-kappaB), an effect that was not modified by cerivastatin. Furthermore, an inhibitor of NF-kappaB translocation, pyrrolidine dithiocarbamate failed to modify both the downregulation of eNOS expression and the increased binding activity of the cytosolic proteins to 3'-UTR of eNOS mRNA by TNF-alpha. The effect of cerivastatin on eNOS expression and the binding activity of the cytosolic proteins were reversed by coincubation with L-mevalonate. In conclusion, cerivastatin stabilized eNOS mRNA and upregulated eNOS expression in the endothelium, and this was associated with a decreased binding activity of cytosolic proteins to 3'-UTR of eNOS mRNA. The effect of cerivastatin on the regulation of eNOS expression was independent of NF-kappaB mobilization by TNF-alpha. These findings suggest that cerivastatin may have beneficial effects on the endothelial dysfunction associated with cardiovascular diseases beyond its effect on lowering cholesterol.

Improvement of coronary artery endothelial dysfunction with lipid-lowering therapy: heterogeneity of segmental response and correlation with plasma-oxidized low density lipoprotein

OBJECTIVES

This study assessed coronary artery endothelial function in patients with hypercholesterolemia before and after lipid lowering, using quantitative angiography to examine the acetylcholine (Ach) response along the entire analyzable vessel.

BACKGROUND

Lipid lowering reverses endothelial dysfunction, but whether improvement occurs only in some segments and not others has not been established. Statistical correlation of improvement with specific lipid moieties remains undefined.

METHODS

Quantitative angiography was performed after Ach (10(-6), 10(-5), 10(-4) M) in 29 patients with coronary atherosclerosis before and 18 +/- 5.2 months after lipid-lowering treatment (statins, bile sequestrant resins). Standard lipid moieties and markers of oxidized low density lipoprotein (LDL) (immunoglobulin G and M autoantibody titers to malondialdehyde-LDL, E06 epitope) were measured serially.

RESULTS

Pre-treatment of the vessel diameters at control and with 10(-6)M, 10(-5) M and 10(-4) M Ach were 2.108 +/- 0.085, 2.086 +/- 0.087, 2.069 +/- 0.084 and 1.963 +/- 0.097 mm (M +/- SE), respectively, and increased at follow-up to 2.139 +/- 0.094, 2.119 +/- 0.086, 2.127 +/- 0.084 and 2.080 +/- 0.085 mm (p < 0.0001). Improvement in the most constricted and modest declination in the more dilated segments were observed. Change in the E06 and Apolipoprotein A-1 titers correlated with improved vasomotion (p = 0.027 and 0.005, respectively). The pre- and post-treatment levels of the E06 epitope, as well as the post-treatment IgM autoantibody titer to MDA-low density lipoprotein, also correlated (p < 0.028, < 0.001 and p < 0.004, respectively).

CONCLUSIONS

Drug treatment reverses endothelial dysfunction, but the effect is heterogeneous. Most coronary segments show enhancement, while others show declination of dilation, underscoring the importance of assessing the entire analyzable artery. Improvement in vasomotion correlates most significantly with markers of plasma-oxidized low-density lipoprotein.

Effect of simvastatin on vascular smooth muscle responsiveness: involvement of Ca(2+) homeostasis

This report is focused on the study of simvastatin-induced relaxation of rat aorta through its effects on vascular smooth muscle and Ca(2+) signalling. The presence of endothelium affected only the simvastatin-induced relaxation of aortic rings precontracted with noradrenaline, but not by depolarization with KCl 80 mM. Blockade of Ca(2+) entry through voltage-operated Ca(2+) channels (VOCCs) by diltiazem abolished the endothelium-dependent and direct relaxation, whereas Ca(2+)-ATPase inhibition by cyclopiazonic acid (3 x 10(-5) M) only affected the endothelium-dependent relaxation. In KCl-depolarised arteries concentration-response curves for CaCl(2) were shifted to the right in the presence of simvastatin (3 x 10(-6) and 3 x 10(-5) M) or diltiazem (10(-6) and 10(-7) M). The transient contraction caused by noradrenaline in Ca(2+)-free medium, which is mainly due to intracellular Ca(2+) release, was inhibited by simvastatin (3 x 10(-5) M) or cyclopiazonic acid (3 x 10(-5) M) and the contraction induced by CaCl(2) (2 x 10(-3) M) added after noradrenaline was inhibited by diltiazem and simvastatin. All the reported effects of simvastatin were inhibited by the product of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, mevalonate (10(-3) M). These findings demonstrate that the vascular effects of simvastatin may involve both Ca(2+) release from intracellular stores, which could promote activation of endothelial factors, and blockade of extracellular Ca(2+) entry, which promote relaxations independent of the presence of endothelium. This action on Ca(2+) could be related to the inhibition of isoprenoid synthesis, which subsequently affects the function of G-proteins involved in communication among intracellular Ca(2+) pools and capacitative Ca(2+) entry.

Drug therapy or coronary angioplasty for the treatment of coronary artery disease: new insights

BACKGROUND

In the last decade percutaneous transluminal coronary angioplasty has become a very popular strategy for the treatment of coronary artery disease, although its efficacy in reducing ischemic events and the subsequent need for revascularization has yet to be proved.

METHODS

We reviewed the latest trials that compared percutaneous transluminal coronary angioplasty and medical therapy.

RESULTS

We discuss the potentially favorable effect of lipid-lowering therapy on coronary atherosclerosis and cardiac events and comment on the results of the recent Atorvastatin Versus Revascularization Treatments (AVERT) study that compared lipid-lowering treatment and percutaneous transluminal coronary angioplasty in patients with stable coronary artery disease.

CONCLUSIONS

Medical treatment aimed at reversing plaque growth and promoting plaque stabilization should probably be considered as the initial therapeutic option. Statin class drugs, together with aggressive management of known risk factors, show promise as the first step after appropriate early diagnosis. Revascularization procedures should subsequently be considered for all patients who do not respond to medical treatment or in whom the disease shows clear signs of progression.

Antioxidants and endothelial dysfunction in hyperlipidemia

Endothelial function is abnormal in a variety of diseased states such as hypercholesterolemia and atherosclerosis. This may be secondary to decreased synthesis of nitric oxide (NO) and/or increased degradation of NO due to interaction with superoxide anions. More recent experimental observations demonstrate increased production of superoxide in hyperlipidemia, suggesting that endothelial dysfunction in these states is in part secondary to increased NO metabolism. Enzymes proposed to be involved in increased superoxide production may include xanthine oxidase, the NO synthase, and the NAD(P)H oxidase. Superoxide rapidly reacts with NO to form peroxynitrite (ONOO-), a highly reactive intermediate with cytotoxic properties. Despite experimental evidence for the oxidative stress concept in causing endothelial dysfunction, the results of recent randomized trials to test the influence of antioxidants on coronary event rates and prognosis in patients with coronary artery disease were very disappointing. In all of these studies the use of vitamins such as vitamin E failed to improve the prognosis. In contrast, treatment with angiotensin converting enzyme inhibitors or cholesterol- lowering drugs improved endothelial dysfunction, prevented the activation of superoxide-producing enzymes in cholesterol-fed animals, reduced coronary event rates, and improved prognosis in patients with coronary artery disease. Therefore, inhibition of superoxide production at the enzymatic level rather than symptomatic superoxide scavenging may be the better choice of treatment.

Acute effects of oats and vitamin E on endothelial responses to ingested fat

OBJECTIVE

To assess the effects of oats and vitamin E on endothelial function following a high-fat meal in healthy adults as measured by brachial artery reactivity studies (BARS).

METHODS

A total of 25 men and 25 women (N=50) were recruited from a community population to participate in this randomized, crossover study. All subjects were free of known vascular disease, and female subjects were postmenopausal. Subjects underwent BARS before and after a high-fat meal (50 gm fat) on three occasions 1 week apart, one each with vitamin E 800 IU, oatmeal containing 3 gm beta-glucan, or a comparable bowl of wheat cereal serving as a placebo, in random sequence. The ultrasonographer was blinded to treatment status.

RESULTS

Endothelial function, as measured by brachial artery peak flow during one minute of post-occlusive hyperemia, declined significantly from baseline when the high-fat meal was consumed with the wheat cereal (-13.4%; p=0.02). There was no difference in brachial artery flow change before and after a high-fat meal with oats (+0.37%; p=0.77) or a high-fat meal with vitamin E (+1.87%; p=0.42). No significant differences in flow-mediated vasodilation before and after the high-fat meal were detected among the three supplements.

CONCLUSIONS

Endothelial dysfunction induced by acute fat ingestion in healthy adults is apparently prevented by concomitant ingestion of oats or vitamin E, but not wheat. Nutrient distribution and meal composition may have important implications for cardiovascular health.

[Progress in the knowledge on endothelial dysfunction and its application in clinical practice]

The endothelium plays a crucial role in the maintenance of vascular homeostasis; endothelial cells produce a series of molecules that determine vascular tone and modulate the interactions between the arterial wall components and the circulating blood. Endothelial dysfunction (ED) thus results in significantly impaired physiological responses that often lead to atheroma formation. Recent studies suggest that endothelial dysfunction as assessed invasively during coronary angiography is a prognostic marker. Recently, a non-invasive ultrasound technique has been developed which may allow screening of ED in both patients and healthy subjects. This article reviews current knowledge regarding non-invasive assessment of endothelial dysfunction and proposes potential uses of a promising ultrasound technique.

Regulation of endothelial nitric oxide synthase and endothelin-1 expression by fluvastatin in human vascular endothelial cells

We investigated the effects of fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on endothelial vasoactive substances using human umbilical vein endothelial cells (HUVECs). Incubation of HUVECs with fluvastatin for 12 h increased endothelial nitric oxide synthase (eNOS) mRNA expression in a concentration-dependent manner (peak, 276 +/- 38%, mean +/- S.D., of the control, at 1.0 microM fluvastatin, P<0.01). In addition, fluvastatin increased eNOS protein production (245 +/- 51% of the control level, P<0.05) as well as nitrite production (165 +/- 35% of the control level, P<0.01). In contrast, incubation of HUVECs with 1.0 microM fluvastatin for 12 h significantly reduced the production of endothelin-1 (ET-1) and preproET-1 mRNA expression in HUVECs (28 +/- 1% and 39 +/- 1% of the control level, respectively, P<0.01). Our results suggest that fluvastatin might be involved in improvement of endothelial function and prevention of the progression of atherosclerosis.

Simvastatin and Ca(2+) signaling in endothelial cells: involvement of rho protein

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor simvastatin is able to produce endothelium-dependent relaxation in addition to its lipid-lowering properties. The underlying mechanisms were investigated in bovine aortic endothelial cells (BAEC). Simvastatin induced an increase in cytosolic calcium ([Ca(2+)](i)) in BAEC, by releasing Ca(2+) from intracellular stores sensitive to thapsigargin and ryanodine, and increasing Ca(2+) entry. Simvastatin response was not altered by the phospholipase A(2) inhibitor ONO-RS-082, or the combination of superoxide dismutase plus catalase. However, the response to simvastatin was reduced by the product of HMG-CoA reductase, mevalonate or by the inhibitor of small G proteins of the Rho family, Clostridium botulinum C3 toxin. Thus, increase in [Ca(2+)](i) involving the activation of Rho protein through mevalonate-dependent pathway is essential for the action of simvastatin and might contribute to its beneficial effects against vascular diseases. This study helps elucidate the mechanisms of endothelial factor generation by simvastatin in BAEC.

Pluripotential mechanisms of cardioprotection with HMG-CoA reductase inhibitor therapy

Treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been accompanied by a reduced risk of cardiovascular events. Rapid onset of clinical benefit and weak correlations between plasma low density lipoprotein-cholesterol levels and coronary lumen change or cardiovascular events indicates that nonlipid mechanisms are involved in this beneficial effects with HMG-CoA reductase inhibitors. Furthermore, more rapid onset of clinical benefit with HMG-CoA reductase inhibitors in patients with acute coronary syndromes or acute myocardial infarction than in those with stable coronary heart disease suggest that HMG-CoA reductase inhibitors facilitate repair of ruptured or ulcerated atherosclerotic plaque, facilitate plaque stabilization and/or reduce thrombus formation on ruptured plaques. Treatment with HMG-CoA reductase inhibitors improved endothelial dysfunction in patients with hypercholesterolemia and this improvement in endothelial function was not correlated with reduction in total serum cholesterol levels. Similarly, reduction in endothelial pre-proendothelin mRNA expression and endothelin synthesis and blood pressure lowering with HMG-CoA reductase inhibitors occurred independent of lipid-lowering. Finally, HMG-CoA reductase inhibitors increased endothelial nitric oxide levels i.e. upregulated endothelial nitric oxide synthetase expression via post-transcriptional mechanisms and prevented its down-regulation by oxidized LDL-C. HMG-CoA reductase inhibitors have been shown to modulate the immune response by inhibiting activation of immune-competent cells such as macrophages, and antigen presentation to macrophages by T cells. Treatment with HMG-CoA reductase inhibitors can reduce expression, production and circulating levels of chemokines (monocyte chemoattractant protein-1) and proinflammatory cytokines [tumor necrosis factoralpha, interleukin (IL)-6 and IL-1beta]. HMG-CoA reductase inhibitors reduced inflammation in human atheroma: significantly fewer macrophages and T cells, less oxidized LDL-C and higher collagen content. In addition, treatment with HMG-CoA reductase inhibitor led to decreased cell death within the atheroma. Treatment with these agents also reduced expression of inducible cellular adhesion molecules, decreased secretion of metalloproteinases by macrophages, reduced vascular smooth muscle cell apoptosis. Lastly, HMG-CoA reductase inhibitors appear to have important effects on the thrombogenesis: reduced expression of tissue factor production and activity; increased production of tissue factor package inhibitor; decreased platelet thrombus formation and improved fibrinolysis as a result of lowered plasminogen activator inhibitor-1 levels. As the pluripotential cardioprotective mechanisms of HMG-CoA reductase inhibitors are further elucidated, it is envisaged that treatment with HMG-CoA reductase inhibitors will be initiated earlier and more frequently in patients with hypercholesterolemia.

Simvastatin preserves coronary endothelial function in hypercholesterolemia in the absence of lipid lowering

Recent evidence suggests that some benefit from the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors may occur independent of lipid lowering. We aimed to determine the effect of simvastatin on coronary endothelial function, endothelial NO synthase (eNOS) expression, and oxidative stress in experimental hypercholesterolemia (HC) in the absence of cholesterol lowering. Pigs were randomized to 3 experimental groups: normal diet (N group), high cholesterol diet (HC group), and HC diet with simvastatin (HC+S group) for 12 weeks. Low density lipoprotein cholesterol was similarly increased in the HC and HC+S groups compared with the N group. In vitro analysis of coronary large- and small-vessel endothelium-dependent vasorelaxation was performed. The mean vasorelaxation of epicardial vessels to bradykinin was significantly attenuated in the HC group compared with the N group (32.3+/-1.2% versus 42.9+/-1.6%, respectively; P<0.0001). This attenuation was significantly reversed in the HC+S group (38.7+/-1.5%, P<0.005 versus HC group). The maximal vasorelaxation to substance P was significantly attenuated in the HC group compared with the N group (50.5+/-11.9% versus 79.3+/-5.3%, respectively; P<0.05). This attenuated response was normalized in the HC+S group (74.9+/-4.1%, P<0.05 versus HC group). The maximal arteriolar vasorelaxation to bradykinin was also significantly attenuated in the HC group compared with the N group (71.9+/-4.9% versus 96.8+/-1.34%, respectively; P<0.005). This was reversed in the HC+S group (98.4+/-0.6%, P<0.0001 versus HC group). Western blotting of coronary tissue homogenates for eNOS demonstrated a decrease in protein levels in the HC group compared with the N group, with normalization in the HC+S group. Elevation of plasma F(2)-isoprostanes and thiobarbituric acid-reactive substances, markers of oxidative stress, occurred in the HC compared with the N group. These changes were reversed in the HC+S group. In summary, simvastatin preserves endothelial function in coronary epicardial vessels and arterioles in experimental HC (in the absence of cholesterol lowering) in association with an increase in coronary eNOS levels and a decrease in oxidative stress. These alterations may play a role in the reduction in cardiac events after treatment with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors.

Multiple endothelial injury in epicardial coronary artery induces downstream microvascular spasm as well as remodeling partly via thromboxane A2

OBJECTIVES

The study was undertaken to develop a coronary microvascular spasm model in pigs by repeated epicardial coronary artery endothelial injury.

BACKGROUND

The pathophysiologic mechanisms responsible for coronary microvascular spasm remain unclear, in large part because a suitable animal model has yet to be found.

METHODS

Balloon endothelial denudation was done just distal to the site of an implanted Doppler flowmeter in the left anterior descending coronary artery (LAD) every two weeks for a total of four times. Changes in LAD blood flow by intracoronary administration of vasoactive agents were assessed before each denudation.

RESULTS

In the epicardial LAD endothelial denudation pigs, decreases in LAD blood flow caused by acetylcholine were augmented. Before denudation, it was - 15 +/- 4%, and at week 8 (i.e., two weeks after the fourth denudation) it was -100% (i.e., zero flow [p < 0.01]). The LAD flow changes in response to 5-hydroxytryptamine (5-HT) changed from an increase to a decrease, accompanied by medial thickening of microvessels in the LAD perfusion area. These flow responses were observed without significant changes in LAD diameter. In contrast, the LAD blood flow responses to acetylcholine and 5-HT did not change throughout the experiment in pigs given aspirin and a thromboxane A2 (TXA2) synthase inhibitor orally.

CONCLUSIONS

This microvascular spasm model indicates that hypersensitivity to vasoactive substances in the microvascular beds as well as microvascular remodeling are brought about partly through TXA2. This model should be useful for examining the pathophysiology and treatment of microvascular angina.

Simvastatin improves disturbed endothelial barrier function

BACKGROUND

Recent clinical trials have established that inhibitors of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) reduce the risk of acute coronary events. These effects of statins cannot be fully explained by their lipid-lowering potential. Improved endothelial function may contribute to the positive effects of statin treatment.

METHODS AND RESULTS

In the present study, we report that simvastatin reduces endothelial barrier dysfunction, which is associated with the development of atherosclerosis. Treatment of human umbilical vein endothelial cells for 24 hours with 5 micromol/L simvastatin reduced the thrombin-induced endothelial barrier dysfunction in vitro by 55+/-3%, as assessed by the passage of peroxidase through human umbilical vein endothelial cell monolayers. Similar effects were found on the thrombin-induced passage of (125)I-LDL through human aortic endothelial cell monolayers. This reduction in barrier dysfunction by simvastatin was both dose and time dependent and was accompanied by a reduction in the thrombin-induced formation of stress fibers and focal adhesions and membrane association of RhoA. Simvastatin treatment had no effect on intracellular cAMP levels. In Watanabe heritable hyperlipidemic rabbits, treatment for 1 month with 15 mg/kg simvastatin reduced vascular leakage in both the thoracic and abdominal part of the aorta, as evidenced by the Evans blue dye exclusion test. The decreased permeability was not accompanied by a reduction of oil red O-stainable atherosclerotic lesions.

CONCLUSIONS

These data show that simvastatin, in a relatively high concentration, improves disturbed endothelial barrier function both in vitro and in vivo. The data also support the beneficial effects of simvastatin in acute coronary events by mechanisms other than its lipid-lowering effect.

Beneficial effects of statins in coronary artery disease--beyond lowering cholesterol

OBJECTIVE

To review the benefits of statins in coronary artery disease management beyond their cholesterol-lowering effects.

DATA SOURCES

A MEDLINE search (1966-May 2000) was conducted using the following terms: lovastatin, pravastatin, simvastatin, atorvastatin, fluvastatin, cerivastatin, endothelium, plaque stabilization, antithrombotic effects.

STUDY SELECTION

English-language human studies and case reports.

DATA EXTRACTION

Studies published demonstrating other mechanisms of statins' clinical beneficial effects were evaluated and reviewed.

DATA SYNTHESIS

The understanding of the pharmacologic effects of statins has led to the realization that the benefits of these agents extend beyond simply lowering cholesterol. These properties include beneficial effects on vessel endothelial tissue; decreased low-density lipoprotein oxidation and inflammation; ability to stabilize atherosclerotic plaques and perhaps promote regression; proliferative effects on smooth-muscle growths, possibly strengthening atherosclerotic plaques; antithrombotic effects by inhibiting platelet aggregation and stimulation of fibrinolytic factors; and improvement of blood viscosity and flow. With these actions, statins may benefit the situation of long-term atherosclerotic plaque formation and the setting of acute coronary syndrome.

CONCLUSIONS

Further large-scale studies are needed to determine the clinical importance and validity of these postulated beneficial effects of statins.

Improvement in endothelium-dependent brachial artery flow-mediated vasodilation with low-density lipoprotein cholesterol levels <100 mg/dl

To determine whether the current National Cholesterol Education Program cholesterol recommendations are consistent with beneficial endothelium-dependent vasodilation, we prospectively assessed endothelium-dependent brachial artery vasoreactivity in 50 patients with stable coronary artery disease. Our results showed that endothelial-dependent vasoreactivity was greater when low-density lipoprotein cholesterol was <100 mg/dl, suggesting that it may be beneficial to reach the National Cholesterol Education Program Adult Treatment Panel II target of low-density lipoprotein cholesterol of <100 mg/dl.

Statin therapy, lipid levels, C-reactive protein and the survival of patients with angiographically severe coronary artery disease

OBJECTIVES

The joint predictive value of lipid and C-reactive protein (CRP) levels, as well as a possible interaction between statin therapy and CRP, were evaluated for survival after angiographic diagnosis of coronary artery disease (CAD).

BACKGROUND

Hyperlipidemia increases risk of CAD and myocardial infarction. For first myocardial infarction, the combination of lipid and CRP levels may be prognostically more powerful. Although lipid levels are often measured at angiography to guide therapy, their prognostic value is unclear.

METHODS

Blood samples were collected from a prospective cohort of 985 patients diagnosed angiographically with severe CAD (stenosis > or =70%) and tested for total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and CRP levels. Key risk factors, including initiation of statin therapy, were recorded, and subjects were followed for an average of 3.0 years (range: 1.8 to 4.3 years) to assess survival.

RESULTS

Mortality was confirmed for 109 subjects (11%). In multiple variable Cox regression, levels of TC, LDL, HDL and the TC:HDL ratio did not predict survival, but statin therapy was protective (adjusted hazard ratio [HR] = 0.49, p = 0.04). C-reactive protein levels, age, left ventricular ejection fraction and diabetes were also independently predictive. Statins primarily benefited subjects with elevated CRP by eliminating the increased mortality across increasing CRP tertiles (statins: HR = 0.97 per tertile, p-trend = 0.94; no statins: HR = 1.8 per tertile, p-trend < 0.0001).

CONCLUSIONS

Lipid levels drawn at angiography were not predictive of survival in this population, but initiation of statin therapy was associated with improved survival regardless of the lipid levels. The benefit of statin therapy occurred primarily in patients with elevated CRP.

Effect of preoperative statin therapy and cardiac outcomes after coronary artery bypass grafting

Preoperative statin administration in this analysis showed improved cardiovascular outcomes after coronary artery bypass graft surgery, including death, myocardial infarction, unstable angina, and arrhythmias.