Intensive lipid lowering by statin therapy does not improve vasoreactivity in patients with type 2 diabetes

The Influence of Statins on the Aerobic Metabolism of Endothelial Cells

Endothelial mitochondrial dysfunction is considered to be the main cause of cardiovascular disease. The aim of this research was to elucidate the effects of cholesterol-lowering statins on the aerobic metabolism of endothelial cells at the cellular and mitochondrial levels. In human umbilical vein endothelial cells (EA.hy926), six days of exposure to 100 nM atorvastatin (ATOR) induced a general decrease in mitochondrial respiration. No changes in mitochondrial biogenesis, cell viability, or ATP levels were observed, whereas a decrease in Coenzyme Q10 (Q10) content was accompanied by an increase in intracellular reactive oxygen species (ROS) production, although mitochondrial ROS production remained unchanged. The changes caused by 100 nM pravastatin were smaller than those caused by ATOR. The ATOR-induced changes at the respiratory chain level promoted increased mitochondrial ROS production. In addition to the reduced level of mitochondrial Q10, the activity of Complex III was decreased, and the amount of Complex III in a supercomplex with Complex IV was diminished. These changes may cause the observed decrease in mitochondrial membrane potential and an increase in Q10 reduction level as a consequence, leading to elevated mitochondrial ROS formation. The above observations highlight the role of endothelial mitochondria in response to potential metabolic adaptations related to the chronic exposure of endothelial cells to statins.

The effects of oxidative stress on the development of atherosclerosis

Atherosclerosis is a cardiovascular disease (CVD) known widely world wide. Several hypothesizes are suggested to be involved in the narrowing of arteries during process of atherogenesis. The oxidative modification hypothesis is related to oxidative and anti-oxidative imbalance and is the most investigated. The aim of this study was to review the role of oxidative stress in atherosclerosis. Furthermore, it describes the roles of oxidative/anti-oxidative enzymes and compounds in the macromolecular and lipoprotein modifications and in triggering inflammatory events. The reactive oxygen (ROS) and reactive nitrogen species (RNS) are the most important endogenous sources produced by non-enzymatic and enzymatic [myeloperoxidase (MPO), nicotinamide adenine dinucleotide phosphate (NADH) oxidase and lipoxygenase (LO)] reactions that may be balanced with anti-oxidative compounds [glutathione (GSH), polyphenols and vitamins] and enzymes [glutathione peroxidase (Gpx), peroxiredoxins (Prdx), superoxide dismutase (SOD) and paraoxonase (PON)]. However, the oxidative and anti-oxidative imbalance causes the involvement of cellular proliferation and migration signaling pathways and macrophage polarization leads to the formation of atherogenic plaques. On the other hand, the immune occurrences and the changes in extra cellular matrix remodeling can develop atherosclerosis process.

The continuums of impairment in vascular reactivity across the spectrum of cardiometabolic health: A systematic review and network meta-analysis

This study aimed to assess, for the first time, the change in vascular reactivity across the full spectrum of cardiometabolic health. Systematic searches were conducted in MEDLINE and EMBASE databases from their inception to March 13, 2017, including studies that assessed basal vascular reactivity in two or more of the following health groups (aged ≥18 years old): healthy, overweight, obesity, impaired glucose tolerance, metabolic syndrome, or type 2 diabetes with or without complications. Direct and indirect comparisons of vascular reactivity were combined using a network meta-analysis. Comparing data from 193 articles (7226 healthy subjects and 19344 patients), the network meta-analyses revealed a progressive impairment in vascular reactivity (flow-mediated dilation data) from the clinical onset of an overweight status (-0.41%, 95% CI, -0.98 to 0.15) through to the development of vascular complications in those with type 2 diabetes (-4.26%, 95% CI, -4.97 to -3.54). Meta-regressions revealed that for every 1 mmol/l increase in fasting blood glucose concentration, flow-mediated dilation decreased by 0.52%. Acknowledging that the time course of disease may vary between patients, this study demonstrates multiple continuums of vascular dysfunction where the severity of impairment in vascular reactivity progressively increases throughout the pathogenesis of obesity and/or insulin resistance, providing information that is important to enhancing the timing and effectiveness of strategies that aim to improve cardiovascular outcomes.

Atorvastatin affects negatively respiratory function of isolated endothelial mitochondria

The purpose of this research was to elucidate the direct effects of two popular blood cholesterol-lowering drugs used to treat cardiovascular diseases, atorvastatin and pravastatin, on respiratory function, membrane potential, and reactive oxygen species formation in mitochondria isolated from human umbilical vein endothelial cells (EA.hy926 cell line). Hydrophilic pravastatin did not significantly affect endothelial mitochondria function. In contrast, hydrophobic calcium-containing atorvastatin induced a loss of outer mitochondrial membrane integrity, an increase in hydrogen peroxide formation, and reductions in maximal (phosphorylating or uncoupled) respiratory rate, membrane potential and oxidative phosphorylation efficiency. The atorvastatin-induced changes indicate an impairment of mitochondrial function at the level of ATP synthesis and at the level of the respiratory chain, likely at complex I and complex III. The atorvastatin action on endothelial mitochondria was highly dependent on calcium ions and led to a disturbance in mitochondrial calcium homeostasis. Uptake of calcium ions included in atorvastatin molecule induced mitochondrial uncoupling that enhanced the inhibition of the mitochondrial respiratory chain by atorvastatin. Our results indicate that hydrophobic calcium-containing atorvastatin, widely used as anti-atherosclerotic agent, has a direct negative action on isolated endothelial mitochondria.

THE EFFECT OF DIABETES ON CARDIOVASCULAR SYSTEM

Diabetes mellitus (DM) is a critical and long-term disorder due to the insufficient production of insulin by the pancreas or ineffective use of insulin by the body. Importantly, cardiovascular disease (CVD) has long been thought to be linked with diabetes. Despite more diabetic individuals surviving from better medications and treatments, there has been significant rise in the morbidity and mortality from CVD. Indeed, the classification of DM based on the electrocardiogram signals of the heart will be an advantageous system. Further, computer-aided classification of DM with integrated algorithms may enhance the execution of the system. In this paper, we have reviewed various studies using heart rate variability signals for automated classification of diabetes. Furthermore, the different techniques used to extract the features and the efficiency of the classification systems are discussed.

The Central Role of Endothelial Dysfunction in Cardiorenal Syndrome

BACKGROUND

Endothelial dysfunction (ED) has emerged as a critical process in cardiorenal syndrome (CRS). The concept that ED is closely linked with cardiac and renal dysfunction has become an important target for CRS-related research and clinical practice.

SUMMARY

The sequence of events leading to ED is initiated by type I endothelial activation (almost immediately) and type II endothelial activation (over hours, days, and even months), followed by endothelial apoptosis and endothelial necrosis. The fact that ED is a continual cellular event divides this process into reversible ED (endothelial activation) and irreversible ED (endothelial apoptosis and necrosis). This basic research-defined concept may have clinical implications. Although most antihypertensive drugs (ACE inhibitors, statins, etc.) are effective in patients with hypertension and diabetes, some of them have proved to be ineffective, which may partly be attributed to irreversible ED. Even though the etiology of ED consists mainly of asymmetric dimethylarginine, nitric oxide, oxidative stress, and anti-endothelial cell antibodies, many other inducers of ED have been identified. In addition, a distinct role of ED has been reported for each type of CRS in humans.

KEY MESSAGES

Further study is warranted to prove whether ED holds promise as a pharmacological target in CRS patients.

Do Statins Lower Blood Pressure?

Hypercholesterolemia is present in many patients with hypertension and adds a significant component of cardiovascular risk. The 3-hydroxy-3 methyl-glutarylcoenzyme A reductase inhibitors (statins) lower low-density lipoprotein cholesterol but also inhibit many of the structural and functional components of the arteriosclerotic process. Structural effects include reductions in vascular smooth muscle hypertrophy and proliferation, fibrin deposition, and collagen cross-linking. Among the functional effects are improvements in endothelial function, reduction in inflammatory cytokines and reactive oxygen species, and down-regulation of angiotensin II and endothelin receptors. These would be expected to reduce blood pressure in patients with hypertension; 14 studies have shown statin-induced decrease in blood pressure, but 11 studies showed no effect. Many of the studies had no placebo controls, were of short duration, or had small sample sizes, or combinations of these. Despite predictions made on the basis of the vasoprotective actions of statins, the blood-pressure-lowering effects of statins are at best modest.

Endothelial dysfunction in diabetes: pathogenesis, significance, and treatment

Type 2 diabetes (T2D) markedly increases the risk of cardiovascular disease. Endothelial dysfunction (ED), an early indicator of diabetic vascular disease, is common in T2D and independently predicts cardiovascular risk. Although the precise pathogenic mechanisms for ED in T2D remain unclear, at inception they probably involve uncoupling of both endothelial nitric oxide synthase activity and mitochondrial oxidative phosphorylation, as well as the activation of vascular nicotinamide adenine dinucleotide phosphate oxidase. The major contributing factors include dyslipoproteinemia, oxidative stress, and inflammation. Therapeutic interventions are designed to target these pathophysiological factors that underlie ED. Therapeutic interventions, including lifestyle changes, antiglycemic agents and lipid-regulating therapies, aim to correct hyperglycemia and atherogenic dyslipidemia and to improve ED. However, high residual cardiovascular risk is seen in both research and clinical practice settings. Well-designed studies of endothelial function in appropriately selected volunteers afford a good opportunity to test new therapeutic interventions, paving the way for clinical trials and utilization in the care of the diabetic patient. However, based on the results from a recent clinical trial, niacin should not be added to a statin in individuals with low high-density lipoprotein cholesterol and very well controlled low-density lipoprotein cholesterol.

Anti-inflammatory effect of atorvastatin on vascular reactivity and insulin resistance in fructose fed rats

We investigated the possible protective effect of atorvastatin against vascular dysfunction associated with insulin resistance (IR) in fructose-fed model rats. The effect of atorvastatin (10 mg/kg/day for 8 weeks) on vascular reactivity, glucose, cholesterol, insulin, and the IR index in a well-established model of dietary hypertriglyceridemia, the fructose-fed rat, was investigated. Fructose feeding (10% fructose in drinking water for 8 weeks) induced hypercholesterolemia and hyperinsulinemia without any change in blood glucose levels. Fructose feeding also elevated serum tumor necrosis factor-alpha (TNF-α), the insulin resistance index, leukocyte infiltration, and endothelial cell pyknosis. Fructose feeding induced hyper-responsiveness to both phenylephrine (PE), KCl, and hyporesponsiveness to acetylcholine (Ach) but not to sodium nitroprusside-induced relaxation. Atorvastatin, given concurrently with fructose, reduced hypercholesterolemia, hyperinsulinemia, TNF-α level, and the IR index. It also reduced leukocyte infiltration and endothelial cell pyknosis and decreased hyper-responsiveness to both PE and KCl but did not affect hyporesponsiveness to Ach relaxation. In conclusion, atorvastatin protected against impairment in aortic vascular reactivity associated with insulin resistance, particularly increased contractility, but not reduced endothelium-dependent relaxation, by a mechanism involving a reduction in cholesterol and IR in addition to anti-inflammatory effects.

Nitric oxide and oxidative stress in vascular disease

Endothelium-derived nitric oxide (NO) is a paracrine factor that controls vascular tone, inhibits platelet function, prevents adhesion of leukocytes, and reduces proliferation of the intima. An enhanced inactivation and/or reduced synthesis of NO is seen in conjunction with risk factors for cardiovascular disease. This condition, referred to as endothelial dysfunction, can promote vasospasm, thrombosis, vascular inflammation, and proliferation of vascular smooth muscle cells. Vascular oxidative stress with an increased production of reactive oxygen species (ROS) contributes to mechanisms of vascular dysfunction. Oxidative stress is mainly caused by an imbalance between the activity of endogenous pro-oxidative enzymes (such as NADPH oxidase, xanthine oxidase, or the mitochondrial respiratory chain) and anti-oxidative enzymes (such as superoxide dismutase, glutathione peroxidase, heme oxygenase, thioredoxin peroxidase/peroxiredoxin, catalase, and paraoxonase) in favor of the former. Also, small molecular weight antioxidants may play a role in the defense against oxidative stress. Increased ROS concentrations reduce the amount of bioactive NO by chemical inactivation to form toxic peroxynitrite. Peroxynitrite-in turn-can "uncouple" endothelial NO synthase to become a dysfunctional superoxide-generating enzyme that contributes to vascular oxidative stress. Oxidative stress and endothelial dysfunction can promote atherogenesis. Therapeutically, drugs in clinical use such as ACE inhibitors, AT(1) receptor blockers, and statins have pleiotropic actions that can improve endothelial function. Also, dietary polyphenolic antioxidants can reduce oxidative stress, whereas clinical trials with antioxidant vitamins C and E failed to show an improved cardiovascular outcome.

Omega-3 fatty acids plus rosuvastatin improves endothelial function in South Asians with dyslipidemia

Background:

The present study was undertaken to investigate the effect of statins plus omega-3 polyunsaturated fatty acids (PUFAs) on endothelial function and lipid profile in South Asians with dyslipidemia and endothelial dysfunction, a population at high risk for premature coronary artery disease.

Methods:

Thirty subjects were randomized to rosuvastatin 10 mg and omega-3-PUFAs 4 g or rosuvastatin 10 mg. After 4 weeks, omega-3-PUFAs were removed from the first group and added to subjects in the second group. All subjects underwent baseline, 4-, and 8-week assessment of endothelial function and lipid profile.

Results:

Compared to baseline, omega-3-PUFAs plus rosuvastatin improved endothelial-dependent vasodilation (EDV: −1.42% to 11.36%, p = 0.001), and endothelial-independent vasodilation (EIV: 3.4% to 17.37%, p = 0.002). These effects were lost when omega-3-PUFAs were removed (EDV: 11.36% to 0.59%, p = 0.003). In the second group, rosuvastatin alone failed to improve both EDV and EIV compared to baseline. However, adding omega-3-PUFAs to rosuvastatin, significantly improved EDV (−0.66% to 14.73%, p = 0.001) and EIV (11.02% to 24.5%, p = 0.001). Addition of omega-3-PUFAs further improved the lipid profile (triglycerides 139 to 91 mg/dl, p = 0.006, low-density lipoprotein cholesterol 116 to 88 mg/dl, p = 0.014).

Conclusions:

Combined therapy with omega-3-PUFAs and rosuvastatin improves endothelial function in South Asian subjects with dyslipidemia and endothelial dysfunction.

Cholesterol lowering is more important than pleiotropic effects of statins for endothelial function in patients with dysglycaemia and coronary artery disease

AIMS

The importance of pleiotropic effects of statins on endothelial function and inflammatory markers was investigated in patients with dysglycaemia and coronary artery disease (CAD).

METHODS AND RESULTS

Thirty-nine patients were randomized to simvastatin 80 mg daily (S80; n = 20) or ezetimibe 10 mg and simvastatin 10 mg daily (E10/S10; n = 19) for 6 weeks, aiming at similar cholesterol reduction. Endothelial function, evaluated by brachial artery flow-mediated vasodilatation (FMD) and the effect of endothelin receptor blockade, serum lipids, and inflammatory markers were evaluated at baseline and follow-up. At follow-up, low-density lipoprotein cholesterol decreased from 3.1 (2.8-3.4) (median and quartiles) to 1.5 mmol/L (1.4-1.7) and from 3.0 (2.5-3.4) to 1.3 mmol/L (1.1-1.8), in the S80 and E10/S10 groups, respectively. In the entire study group, FMD increased from 4.3% (3.4-6.1) at baseline to 5.5% (3.4-6.6) at follow-up, while C-reactive protein decreased from 3.1 (1.7-7.6) to 2.3 mg/L (0.9-6.5). The changes in FMD and C-reactive protein from baseline to follow-up were not significantly different between patients on S80 and E10/S10 groups. Endothelin blockade enhanced endothelium-dependent vasodilatation both at baseline and follow-up.

CONCLUSION

Lipid lowering is more important than pleiotropic effects of statins for improvement in endothelial function and inflammatory markers in patients with dysglycaemia and CAD.

Endothelial dysfunction in diabetes mellitus

Diabetes mellitus is associated with an increased risk of cardiovascular disease, even in the presence of intensive glycemic control. Substantial clinical and experimental evidence suggest that both diabetes and insulin resistance cause a combination of endothelial dysfunctions, which may diminish the anti-atherogenic role of the vascular endothelium. Both insulin resistance and endothelial dysfunction appear to precede the development of overt hyperglycemia in patients with type 2 diabetes. Therefore, in patients with diabetes or insulin resistance, endothelial dysfunction may be a critical early target for preventing atherosclerosis and cardiovascular disease. Microalbuminuria is now considered to be an atherosclerotic risk factor and predicts future cardiovascular disease risk in diabetic patients, in elderly patients, as well as in the general population. It has been implicated as an independent risk factor for cardiovascular disease and premature cardiovascular mortality for patients with type 1 and type 2 diabetes mellitus, as well as for patients with essential hypertension. A complete biochemical understanding of the mechanisms by which hyperglycemia causes vascular functional and structural changes associated with the diabetic milieu still eludes us. In recent years, the numerous biochemical and metabolic pathways postulated to have a causal role in the pathogenesis of diabetic vascular disease have been distilled into several unifying hypotheses. The role of chronic hyperglycemia in the development of diabetic microvascular complications and in neuropathy has been clearly established. However, the biochemical or cellular links between elevated blood glucose levels, and the vascular lesions remain incompletely understood. A number of trials have demonstrated that statins therapy as well as angiotensin converting enzyme inhibitors is associated with improvements in endothelial function in diabetes. Although antioxidants provide short-term improvement of endothelial function in humans, all studies of the effectiveness of preventive antioxidant therapy have been disappointing. Control of hyperglycemia thus remains the best way to improve endothelial function and to prevent atherosclerosis and other cardiovascular complications of diabetes. In the present review we provide the up to date details on this subject.

Endothelial function, arterial stiffness and lipid lowering drugs

The endothelium is a dynamic organ that plays a pivotal role in cardiovascular homeostasis. Alteration in endothelial function precedes the development of atherosclerosis and contributes to its initiation, perpetuation and clinical manifestations. It has been suggested that the assessment of endothelial function could represent a barometer of vascular health that could be used to gauge cardiovascular risk. This review summarises the various methods used to assess endothelium-dependent vasodilatation and their potential prognostic implications. In addition, the techniques used to evaluate arterial stiffness are discussed. The latter is to some extent controlled by the endothelium and has been the subject of considerable research in recent years. This paper also discusses the effects of lipid lowering treatment on both endothelial function and arterial stiffness.

Therapeutic regulation of endothelial dysfunction in type 2 diabetes mellitus

Endothelial dysfunction is universal in diabetes, being intimately involved with the development of cardiovascular disease. The pathogenesis of endothelial dysfunction in diabetes is complex. It is initially related to the effects of fatty acids and insulin resistance on 'uncoupling' of both endothelial nitric oxide synthase activity and mitochondrial function. Oxidative stress activates protein kinase C (PKC), polyol, hexosamine and nuclear factor kappa B pathways, thereby aggravating endothelial dysfunction. Improvements in endothelial function in the peripheral circulation in diabetes have been demonstrated with monotherapies, including statins, fibrates, angiotensin-converting enzyme (ACE) inhibitors, metformin and fish oils. These observations are supported by large clinical end point trials. Other studies show benefits with certain antioxidants, L-arginine, folate, PKC-inhibitors, peroxisome proliferator activated receptor (PPAR)-alpha and -gamma agonists and phosphodiesterase (PDE-5) inhibitors. However, the benefits of these agents remain to be shown in clinical end point trials. Combination treatments, for example, statins plus ACE inhibitors and statins plus fibrates, have also been demonstrated to have additive benefits on endothelial function in diabetes, but there are no clinical outcome data to date. Measurement of endothelial dysfunction in cardiovascular research can provide fresh opportunities for exploring the mechanism of benefit of new therapeutic regimens and for planning and designing large clinical trials.

Differential impact of atorvastatin vs pravastatin on progressive insulin resistance and left ventricular diastolic dysfunction in a rat model of type II diabetes

BACKGROUND

Controversy exists regarding the effects of statin therapy on progressive insulin resistance (IR) and its consequences, in the present study a rat model of spontaneously developing type II diabetes mellitus (DM) was used to examine the impact of atorvastatin (AS) vs pravastatin (PS).

METHODS AND RESULTS

The Otsuka Long-Evans Tokushima Fatty rats were either untreated or treated with 100 mg/kg per day of AS or PS from 6 weeks of age for 24 weeks. AS achieved much greater lipid lowering than PS. Serial oral glucose tolerance tests revealed new-onset diabetes was delayed by PS only. The untreated rats exhibited a progressive decrease in plasma adiponectin, increases in plasma leptin and tumor necrosis factor-alpha, and reduction of plasma nitric oxide (NO), which were limited more by PS than AS. PS, but not AS, enhanced adiponectin mRNA expression in white adipose tissue at 30 weeks. Cardiac endothelial NO synthase expression was upregulated, and overexpression of both transforming growth factor-beta1 and monocyte chemoattractant protein-1 mRNA was limited more by PS than AS. Coronary perivascular fibrosis at 30 weeks was suppressed only by PS, which was accompanied by preserved left ventricular diastolic function assessed with Doppler echocardiography.

CONCLUSIONS

The moderate lipid lowering by PS, but not the intensive lipid lowering by AS, prevented new-onset DM and diastolic dysfunction in a rat model of IR, and this was associated with preferable adipocytokine profiles and cardiac redox states.

IκB kinase 2 inhibition corrects defective nitrergic erectile mechanisms in diabetic mouse corpus cavernosum

OBJECTIVES

Oxidative or glyco-oxidative stress-induced activation of the transcription factor, nuclear factor (NF)-kappaB, is associated with the neurovascular complications of diabetes mellitus. Antioxidant treatment has beneficial effects in diabetic patients; however, delineating a possible role for NF-kappaB deactivation against direct antioxidant effects has been difficult. NF-kappaB is negatively regulated by the inhibitor of kappaB (IkappaB) complex that, in turn, is activated by specific kinases. Thus, the aim was to investigate the effects of the IkappaB kinase 2 inhibitor, AS602868, on corpus cavernosum function in diabetic mice.

METHODS

Diabetes was induced by streptozotocin; the duration was 6 weeks. Intervention AS602868 treatment (100 mg/kg/day) was given for 2 weeks after 4 weeks of untreated diabetes. Corpora cavernosum were isolated in organ baths for measurement of agonist-evoked or electrical stimulation-evoked smooth muscle tensions.

RESULTS

The maximal nitrergic nerve-mediated relaxation of phenylephrine-precontracted cavernosum was reduced approximately 30% by diabetes (P <0.001). AS602868 treatment completely reversed the deficit (P <0.001). Maximal nitric oxide-mediated endothelium-dependent relaxation to acetylcholine was attenuated approximately 32% by diabetes (P <0.05). This was completely restored by IkappaB kinase 2 inhibition (P <0.01). Furthermore, AS602868 treatment also completely corrected (P <0.01) an approximate 20% diabetic deficit (P <0.001) in maximal endothelium-independent relaxation to the nitric oxide donor, sodium nitroprusside.

CONCLUSIONS

Inhibition of IkappaB kinase 2 can correct nitric oxide-dependent indexes of diabetic erectile dysfunction. This suggests that NF-kappaB activation is important in the development of diabetic cavernosum nitrergic neuropathy and vasculopathy.

The calpain inhibitor, A-705253, corrects penile nitrergic nerve dysfunction in diabetic mice

Calpains, a superfamily of Ca(2+)-activated proteases, are associated with an array of physiological and pathological events, including susceptibility to diabetes. Recently, increased calpain activity has been linked to reduced endothelium-derived nitric oxide-mediated vasodilatation in diabetes. However, a similar mechanism for neuronal-derived nitric oxide has not been examined. Thus, the aim was to investigate effects of the calpain inhibitor A-705253, N-(1-benzyl-2-carbamoyl-2-oxoethyl)-2-[E-2-(4-diethyl-aminomethylphenyl)ethen-1-yl]benzamide, on nitrergic neurovascular function in diabetic mice. Diabetes was induced by streptozotocin; duration was 6 weeks. Intervention A-705253 treatment (30 mg/kg/day) was given for 2 weeks following 4 weeks of untreated diabetes. After 6 weeks of diabetes, corpus cavernosa were isolated in organ baths for measurement of agonist- and electrical stimulation-evoked smooth muscle tensions. Adrenergic nerve- and phenylephrine-mediated contractions were not altered by diabetes or calpain inhibition. In contrast, maximum nitrergic nerve-mediated relaxation of phenylephrine-precontracted cavernosum was approximately 29% reduced by diabetes (P<0.001). This neurological deficit was 66% corrected by A-705253 treatment (P<0.05). Maximum nitric oxide-mediated endothelium-dependent relaxation to acetylcholine was attenuated approximately 39% by diabetes (P<0.01). Similarly, maximum endothelium-independent relaxation to the nitric oxide donor, sodium nitroprusside, was blunted approximately 23% by diabetes (P<0.001). A-705253 treatment partially improved endothelium-dependent relaxation to acetylcholine but had no effect on the deficit in response to nitroprusside. The data suggest that calpain contributes to the aetiology of diabetic nitrergic autonomic neuropathy and endothelial dysfunction, which may provide a novel therapeutic target for neurovascular complications.

The beneficial in vitro effects of lovastatin and chelerythrine on relaxatory response to acetylcholine in the perfused mesentric bed isolated from diabetic rats

Diabetes mellitus is associated with an increased risk of cardiovascular disease. Endothelial dysfunction (i.e. decreased endothelium-dependent vasorelaxation) plays a key role in the pathogenesis of diabetic vascular disease. The present study was undertaken to determine whether diabetes induced by streptozotocin alters mesenteric responses to vasodilators and, if so, to study the acute in vitro effects of lovastatin and chelerythrine. Endothelial function was assessed in constantly perfused preparation removed from rats, 12 weeks after treatment with either saline or streptozotocin (45 mg/kg, intraperitoneally). In pre-contracted mesenteric beds (with 100 microM phenylephrine) removed from diabetic rats, the concentration response curve to acetylcholine, but not to sodium nitroprusside, was significantly reduced. Perfusion with lovastatin (10 microM for 20 min) or chelerythrine (1 microM for 20 min) significantly improved the acetylcholine-mediated relaxation in preparations removed from diabetic but not control rats. Pre-incubation of tissue with N(G)-nitro-L-argenine methyl ester hydrochloride (10 microM for 20 min) inhibited the beneficial effect of lovastatin but not chelerythrine. Pre-treatment of tissue with indomethacin (10 microM for 20 min) did not modify the effects of lovastatin or chelerythrine on acetylcholine responses. The present results demonstrate that endothelial dysfunction induced by diabetes (in a resistant vasculature, such as rat mesenteric bed) may be improved by an acute exposure to either lovastatin or chelerythrine. Furthermore, our results suggest that the beneficial effect of lovastatin is mediated via the nitric oxide pathway.

The effects of lipid-lowering drug therapy on cardiovascular responsiveness in type 2 diabetic patients

Type 2 diabetes is associated with a high prevalence of dyslipidaemia and a high incidence of cardiovascular disease. Lipid lowering therapy with HMG Co-A reductase inhibitors (statins) reduce the risk of cardiovascular events in type 2 diabetic and non-diabetic patients, effects which are believed to be partly due to improvements in vascular function. The aetiology of abnormal vascular function in type 2 diabetics is likely to be multifactorial and the pattern of vascular dysfunction in type 2 diabetes may differ from that which occurs in non-diabetic patients with dyslipidaemia. Abnormalities in endothelium derived hyperpolarising factor (EDHF) mediated vasodilation in resistance vessels may be more prominent in both type 1 and type 2 diabetes than in non-diabetic patients with endothelial dysfunction. The effects of lipid lowering therapy on vascular responsiveness may differ in type 2 diabetic patients from those found in non-diabetic patients. Statin therapy does not appear to improve responses to endothelial dependent vasodilators in type 2 diabetics, but may alter the ratio between nitric oxide (NO) and EDHF mediated responses. Fibrate therapy improves flow mediated dilation of brachial arteries in type 2 diabetic patients, but only appears to improve endothelium dependant vasodilator responses in resistance vessels when given in conjunction with co-enzyme Q.

Pravastatin Decreases Blood Pressure in Hypertensive and Hypercholesterolemic Patients Receiving Antihypertensive Treatment

BACKGROUND

Previous studies have suggested that the lipid-lowering agents, statins, may help reduce blood pressure (BP). The goal of the present study was to characterize the effect of pravastatin on BP in hypercholesterolemic and hypertensive patients already receiving antihypertensive drugs.

METHODS AND RESULTS

Eighty-two patients with hypercholesterolemia were retrospectively studied before and after 3 months of treatment with pravastatin. Forty-four patients had hypertension (HT group) and were receiving antihypertensive treatment, while the remaining 38 patients were normotensive (NT group). Patients in the HT group were further subdivided into those with uncontrolled or controlled BP. Pravastatin treatment significantly reduced systolic BP (SBP) in the HT group (134+/-16 to 130+/-13 mmHg, p<0.005) but not in the NT group (124+/-10 to 123+/-9 mmHg, p=0.52), despite the fact that treatment significantly reduced low-density lipoprotein cholesterol in both groups (HT group 178+/-27 to 132+/-17 mg/dl, p<0.0001; NT group 169+/-27 to 125+/-21 mg/dl, p<0.0001). Further, pravastatin significantly decreased SBP in the uncontrolled BP group (148+/-7 to 138+/-12 mmHg, p<0.005) but not in the controlled BP group (122+/-10 to 123+/-9 mmHg, p=0.72).

CONCLUSION

Concomitant use of statins and antihypertensive drugs could result in improved BP control in hypertensive patients with hypercholesterolemia.

Correction of nitrergic neurovascular dysfunction in diabetic mouse corpus cavernosum by p38 mitogen-activated protein kinase inhibition

Increased p38 mitogen-activated protein kinase (MAPK) in response to stress stimuli, including hyperglycemia, contributes to diabetic somatic neuropathy. However, effects on autonomic nerve and vascular function have not been determined. The aim of this study was to investigate the effects of the p38 MAPK inhibitor, LY2161793, on penile neurovascular function in streptozotocin-induced diabetic mice. Diabetes duration was 6 weeks and intervention LY2161793 treatment was given for the final 2 weeks. In vitro measurements on phenylephrine-precontracted corpus cavernosum revealed a 32% reduction in maximum nitrergic nerve-mediated relaxation with diabetes that was 74% corrected by LY2161793 treatment. Maximum nitric oxide-mediated endothelium-dependent relaxation to acetylcholine was 42% attenuated by diabetes and 88% restored by LY2161793. Moreover, treatment partially corrected a diabetic deficit in endothelium-independent relaxation to a nitric oxide donor. Thus, p38 MAPK inhibition corrects nitric oxide-dependent indices of diabetic erectile autonomic neuropathy and vasculopathy, a therapeutic approach potentially worthy of consideration for clinical trials.

Microvascular endothelial function in subjects with Type 2 diabetes and the effect of lipid-lowering therapy

AIMS

Abnormalities of microvascular and endothelial function are present in subjects with Type 2 diabetes. Although statin therapy improves cardiovascular risk in diabetes, dyslipidaemia in diabetes may be more responsive to combined statin and fibrate therapy. We examined the effect of cerivastatin and fenofibrate on microvascular function in subjects with Type 2 diabetes with no clinical evidence of cardiovascular disease and near normal lipid levels.

METHODS

Age-, sex-, lipid- and blood pressure-matched subjects with Type 2 diabetes were randomized in double-blind fashion to one of four treatment groups: group 1 placebo/placebo (n=12), group 2 fenofibrate/placebo (n=10), group 3 cerivastatin/placebo (n=20) and group 4 cerivastatin/fenofibrate (n=11). The subjects were recruited from the Lipid in Diabetes Study. Microvascular function was assessed by skin blood flow response to iontophoresis of acetylcholine and sodium nitroprusside and by skin maximum hyperaemia to local heating. Measurements were carried out at baseline and 3 months later.

RESULTS

Although all lipid parameters improved in groups 2-4 after 3 months' therapy, no difference was detected in skin blood flow to iontophoresis or maximum hyperaemia in any of the groups. Highly sensitive c-reactive protein (Hs-CRP) did not change with therapy.

CONCLUSIONS

In conclusion, we were unable to demonstrate any improvement in microvascular endothelial function in non-hyperlipidaemic Type 2 diabetic subjects treated with single or combination lipid-lowering therapy.

Effects of rosuvastatin on endothelial function in patients with familial combined hyperlipidaemia (FCH)

OBJECTIVE

Although several studies have reported a positive effect of statins on endothelial vasoreactivity, most studies performed in subjects with type 2 diabetes mellitus report no effect at all. This lack of effect may be related to the existence of insulin resistance, or to insufficient lowering of atherogenic (apo)lipoproteins. Therefore, we tested in this study whether treatment of insulin resistant familial combined hyperlipidaemia (FCH) patients with a high dose (40 mg/day) of the potent rosuvastatin was able to improve endothelial function, without necessarily improving insulin sensitivity.

RESEARCH DESIGN AND METHODS

In a double-blind randomised crossover study, 18 subjects with FCH (without evident cardiovascular disease, mean [standard deviation] age 54 [7] years) underwent a 4-week run-in period after which they were randomised to treatment with placebo once daily for 12 weeks, followed by rosuvastatin 40 mg/day for 12 weeks or vice versa. Endothelial function was determined after 8 and 12 weeks of both treatment periods, respectively, by measurement of flow-mediated vasodilation (FMD) using high-resolution ultrasound and by measurement of vasodilator response to intrabrachial acetylcholine (Ach) by venous occlusion plethysmography (forearm blood flow [FBF]).

RESULTS

Plasma levels of lipids, (apo)lipoproteins and high-sensitivity C-reactive protein (hsCRP) improved significantly after rosuvastatin therapy compared to placebo. However, rosuvastatin had no effect on homeostasis model assessment (HOMA)-indices or on vasodilator responses to intra-brachial acetylcholine-infusion (FBF-ratio increased from a mean of 1.28 [SD: 0.46] to 5.82 [3.44] after rosuvastatin and from 1.33 [0.67] to 5.99 [3.89] after placebo, p = 0.35). Endothelium-dependent FMD was also unchanged (1.6% [3.1%] vs. 3.2% [3.5]%, p = 0.56 rosuvastatin vs. placebo, respectively).

CONCLUSION

In patients with FCH, a 12-week treatment of rosuvastatin 40 mg/day did not improve endothelial function (either in large conduit vessels or in resistance vessels), despite significant improvements in plasma lipids, (apo)lipoproteins. and low-grade inflammation.

Metabolic syndrome and endothelial dysfunction

The incidence of metabolic syndrome is rapidly increasing in the United States. Metabolic syndrome is associated with increased cardiovascular morbidity and mortality, and endothelial dysfunction is an early pathogenetic event in the metabolic syndrome. Endothelial dysfunction of either the coronary, the peripheral, or the cerebral vasculature is a predictor of vascular events and appears to be a marker of uncontrolled atherosclerotic risk that adds to the burden of the genetic predisposition to cardiovascular disease. Clinically and experimentally, endothelial dysfunction can be restored by several agents, including blockers/inhibitors of the renin-angiotensin-aldosterone system, as well as statins. Nevertheless, it would be premature, and most likely inappropriate, to use improvement of endothelial function as a surrogate end point to predict reduction in cardiovascular morbidity and mortality. However, a clear understanding of the mechanisms of endothelial dysfunction in the metabolic syndrome may allow the development of preventive and early therapeutic measures targeting cardiovascular disease.

Clinical impact of vasomotor function assessment and the role of ACE-inhibitors and statins

Impaired endothelial function is recognised as one of the earliest events of atherogenesis. Endothelium-dependent vasomotion has been the principal method to assess endothelial function. In this article, we will discuss the clinical value of the different techniques to evaluate endothelium-dependent vasomotion. To date, there seems not to be a simple and reliably endothelial function test to identify asymptomatic subjects at increased risk for cardiovascular disease in clinical practice. Recent studies indicate that pharmacological interventions, in particular with ACE-inhibitors and statins, might improve endothelial function. However, there is no solid evidence that improvement of endothelial function is a necessity for the observed reduction in cardiovascular events by these compounds. Overall, at this moment, there is no place in clinical practice for the use of endothelial function as a method for risk assessment or target of pharmacological interventions.

The effect of statin therapy on endothelial function in type 2 diabetes without manifest cardiovascular disease

OBJECTIVE

Cardiovascular disease (CVD) is the most important cause of mortality in patients with type 2 diabetes and is preceded by endothelial dysfunction. Flow-mediated dilation (FMD) is a noninvasive technique for measuring endothelial dysfunction. We aimed to determine the effect of long-term statin therapy versus placebo on FMD in patients with type 2 diabetes without manifest CVD.

RESEARCH DESIGN AND METHODS

A randomized, placebo-controlled, double-blind trial was performed with 250 type 2 diabetic patients. Patients were given 0.4 mg cerivastatin or placebo daily. In August 2001, when cerivastatin was withdrawn from the market, the 0.4 mg cerivastatin was replaced by 20 mg simvastatin, without deblinding the study. The primary end point was the change in FMD, measured by B-mode ultrasound, after 2 years.

RESULTS

Determinants of baseline FMD were diabetes duration, common carotid intima-media thickness, and brachial artery diameter. FMD at baseline was 1.51% in the placebo group and 1.66% in the statin group and did not change significantly after 2 years.

CONCLUSIONS

The 2-year statin therapy had no effect on FMD in type 2 diabetes. Statin-induced improvement of cardiovascular risk in patients with type 2 diabetes may be mediated through mechanisms other than increased nitric oxide availability.

Effects of cerivastatin on forearm vascular responses, blood pressure responsiveness and ambulatory blood pressure in type 2 diabetic men

OBJECTIVE

The objective of the study was to investigate the effects of cerivastatin therapy on forearm endothelial dependent acetylcholine (ACH) and independent (nitroprusside) vasodilator responses, blood pressure (BP) responses to intravenous infusions of angiotensin II (AII) and noradrenaline (NA) and on 24-h ambulatory BP recordings in type 2 diabetic men.

DESIGN

Eleven type 2 diabetic men aged 59 +/- 9 years with total cholesterol levels of 5.0 +/- 1.26 mmol/l, triglycerides of 2.23 mmol/l and high-density lipoprotein cholesterol levels of 1.24 mmol/l completed a double-blind, randomized, crossover trial comparing 8 weeks of cerivastatin therapy (800 microg of nocte) with placebo. Forearm vascular resistance (FVR) responses to intrabrachial-arterial infusions of ACH (3-24 microg/min), nitroprusside (2-16 microg/min), the nitric oxide(NO) synthase inhibitor l-nitro-mono-methyl arginine (l-nmma) (8 micromol/min), ACH during l-NMMA infusion and BP responses to intravenous infusions of AII (12.5-50 ng/min) and NA (20-400 ng/min) were measured at the end of each treatment period. Twenty-four-hour ambulatory BP recordings were also performed.

RESULTS

FVR responses to ACH during l-NMMA infusion were significantly (p = 0.026) greater during cerivastatin than during placebo therapy. In contrast, FVR responses to ACH in the absence of NO synthase inhibition did not differ significantly between cerivastatin and placebo therapies (p = 0.81). FVR increased by 31.4 +/- 57.3% in response to l-NMMA infusion during cerivastatin therapy compared with 6.1 +/- 41.2% during placebo therapy (p = 0.20). FVR responses to nitroprusside did not differ between cerivastatin and placebo therapies (p = 0.28), nor did BP responses to AII (systolic BP, p = 0.99; diastolic BP, p = 0.98) or NA (systolic BP, p = 0.21; diastolic BP, p = 0.48). Mean 24-h BP was similar during cerivastatin (123 +/- 10 or 70 +/- 7 mmHg) and placebo therapies (129 +/- 11 or 74 +/- 7 mmHg) (systolic BP, p = 0.26; diastolic BP, p = 0.41).

CONCLUSION

Cerivastatin increases FVR responses to ACH in type 2 diabetic men with mild dyslipidaemia but only following NO synthase inhibition. This may indicate an improvement in endothelium-derived hyperpolarizing factor-mediated responses.

Atorvastatin reduces the plasma lipids and oxidative stress but did not reverse the inhibition of prostacyclin generation by aortas in streptozotocin diabetic rats

The effect of atorvastatin (Lipitor) on diabetes-induced changes in plasma lipids, oxidative stress and the ability of aortic tissues to generate prostacyclin was studied in streptozotocin diabetic rats. In diabetic rats, plasma total cholesterol, triglycerides and serum glucose significantly increased compared to nondiabetic rats. Atorvastatin administration to diabetic rats did not affect hyperglycemia but significantly reduced plasma total cholesterol and triglycerides compared to diabetic rats. The oxidative stress markers urinary isoprostane, liver thiobarbituric acid reactive substances (TBARS) and plasma protein carbonyl content significantly increased in diabetic rats compared to nondiabetic rats. Atorvastatin admnistration to diabetic rats significantly reduced oxidative stress levels compared to diabetic rats, but urinary isoprostane and liver TBARS remained significantly higher than nondiabetic rats. Prostacyclin (PGI(2)) generation by aortic tissues significantly decreased in diabetic rats compared to nondiabetic rats. Atorvastatin administration to diabetic rats did not reverse that inhibition. These results were discussed in the light of the possible effects of hyperglycemia and statins on NAD(P)H-oxidase and cyclooxygenase-2 activities and the genetic difference between rats and other mammals regarding the level of vascular superoxide dismutase (SOD) activity.

Endothelial function and dysfunction. Part II: Association with cardiovascular risk factors and diseases. A statement by the Working Group on Endothelins and Endothelial Factors of the European Society of Hypertension*

Dysfunction of the vascular endothelium is a hallmark of most conditions that are associated with atherosclerosis and is therefore held to be an early feature in atherogenesis. However, the mechanisms by which endothelial dysfunction occurs in smoking, dyslipidaemia, hyperhomocysteinaemia, diabetes mellitus, arterial hypertension, cerebrovascular diseases, coronary artery disease and heart failure are complex and heterogeneous. Recent data indicate that endothelial dysfunction is often associated with erectile dysfunction, which can precede and predict cardiovascular disease in men. This paper will provide a concise overview of the mechanisms causing endothelial dysfunction in the different cardiovascular risk factors and disease conditions, and of the impact of the intervention measures and treatments.

Atorvastatin

Atorvastatin (Lipitor) is an HMG-CoA reductase inhibitor with well documented lipid-lowering effects. It has recently been evaluated for the primary prevention of major cardiovascular events in patients with type 2 diabetes mellitus without elevated serum low-density lipoprotein (LDL)-cholesterol levels. Atorvastatin 10mg daily for 4 years was effective at reducing the risk of a first major cardiovascular event, including stroke, in a large, placebo-controlled, multicentre trial in patients with type 2 diabetes and at least one other coronary heart disease (CHD) risk factor, but without markedly elevated LDL-cholesterol levels. In this trial, known as CARDS (the Collaborative AtoRvastatin Diabetes Study), atorvastatin had a similar tolerability profile to that of placebo. Thus, atorvastatin has a potential role in the primary prevention of cardiovascular events in diabetic patients at risk of CHD, irrespective of pre-treatment LDL-cholesterol levels.

Mechanisms, Significance and Treatment of Vascular Dysfunction in Type 2 Diabetes Mellitus

Endothelial dysfunction and increased arterial stiffness occur early in the pathogenesis of diabetic vasculopathy. They are both powerful independent predictors of cardiovascular risk. Advances in non-invasive methodologies have led to widespread clinical investigation of these abnormalities in diabetes mellitus, generating a wealth of new knowledge concerning the mechanisms of vascular dysfunction, risk factor associations and potential treatment targets. Endothelial dysfunction primarily reflects decreased availability of nitric oxide (NO), a critical endothelium-derived vasoactive factor with vasodilatory and anti-atherosclerotic properties. Techniques for assessing endothelial dysfunction include ultrasonographic measurement of flow-mediated vasodilatation of the brachial artery and plethysmography measurement of forearm blood flow responses to vasoactive agents. Arterial stiffness may be assessed using pulse wave analysis to generate measures of pulse wave velocity, arterial compliance and wave reflection. The pathogenesis of endothelial dysfunction in type 2 diabetes is multifactorial, with principal contributors being oxidative stress, dyslipidaemia and hyperglycaemia. Elevated blood glucose levels drive production of reactive oxidant species (ROS) via multiple pathways, resulting in uncoupling of mitochondrial oxidative phosphorylation and endothelial NO synthase (eNOS) activity, reducing NO availability and generating further ROS. Hyperglycaemia also contributes to accelerated arterial stiffening by increasing formation of advanced glycation end-products (AGEs), which alter vessel wall structure and function. Diabetic dyslipidaemia is characterised by accumulation of triglyceride-rich lipoproteins, small dense low-density lipoprotein (LDL) particles, reduced high-density lipoprotein (HDL)-cholesterol and increased postprandial free fatty acid flux. These lipid abnormalities contribute to increasing oxidative stress and may directly inhibit eNOS activity. Although lipid-regulating agents such as HMG-CoA reductase inhibitors (statins), fibric acid derivatives (fibrates) and fish oils are used to treat diabetic dyslipidaemia, their impact on vascular function is less clear. Studies in type 2 diabetes have yielded inconsistent results, but this may reflect sampling variation and the potential over-riding influence of oxidative stress, dysglycaemia and insulin resistance on endothelial dysfunction. Results of positive intervention trials suggest that improvement in vascular function is mediated by both lipid and non-lipid mechanisms, including anti-inflammatory, anti-oxidative and direct effects on the arterial wall. Other treatments, such as renin-angiotensin-aldosterone system antagonists, insulin sensitisers and lifestyle-based interventions, have shown beneficial effects on vascular function in type 2 diabetes. Novel approaches, targeting eNOS and AGEs, are under development, as are new lipid-regulating therapies that more effectively lower LDL-cholesterol and raise HDL-cholesterol. Combination therapy may potentially increase therapeutic efficacy and permit use of lower doses, thereby reducing the risk of adverse drug effects and interactions. Concomitant treatments that specifically target oxidative stress may also improve endothelial dysfunction in diabetes. Vascular function studies can be used to explore the therapeutic potential and mechanisms of action of new and established interventions, and provide useful surrogate measures for cardiovascular endpoints in clinical trials.

Lipid and non-lipid effects of statins

Long- and short-term trials with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have demonstrated significant reductions in cardiovascular events in patients with and without history of coronary heart disease. Statins are well-established low-density lipoprotein (LDL)-lowering agents, but their clinical benefit is believed to result from a number of lipid and non-lipid effects beyond LDL lowering, including a rise in plasma high-density lipoprotein levels. Beyond improving the lipid profile, statins have additional non-lipid effects including benefit on endothelial function, inflammatory mediators, intima-media thickening, prothombotic factors that ultimately result in plaque stabilization. These effects arise through the inhibition of several mevalonate-derived metabolites other than cholesterol itself, which are involved in the control of different cellular functions. Although statins represent the gold standard in the prevention and treatment of coronary heart disease, combination therapy with other lipid-lowering drugs, as well as novel therapeutic indications, may increase their therapeutic potential.

Beneficial cardiovascular pleiotropic effects of statins

Pleiotropic effects of a drug are actions other than those for which the agent was specifically developed. These effects may be related or unrelated to the primary mechanism of action of the drug, and they are usually unanticipated. Pleiotropic effects may be undesirable (such as side effects or toxicity), neutral, or, as is especially the case with HMG-CoA reductase inhibitors (statins), beneficial. Pleiotropic effects of statins include improvement of endothelial dysfunction, increased nitric oxide bioavailability, antioxidant properties, inhibition of inflammatory responses, and stabilization of atherosclerotic plaques. These and several other emergent properties could act in concert with the potent low-density lipoprotein cholesterol-lowering effects of statins to exert early as well as lasting cardiovascular protective effects. Understanding the pleiotropic effects of statins is important to optimize their use in treatment and prevention of cardiovascular disease.

Effects of the peroxynitrite decomposition catalyst, FeTMPyP, on function of corpus cavernosum from diabetic mice

Peroxynitrite, the reaction product of nitric oxide and superoxide, may contribute to vascular tissue oxidant stress in diabetes mellitus. The aim was to establish whether the peroxynitrite decomposition catalyst 5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphyrinato iron III (FeTMPyP) could improve nitric oxide-dependent autonomic nerve and microvascular penile function in the diabetic mouse. Diabetes was induced by streptozotocin; duration was 6 weeks. Intervention FeTMPyP treatment (25 mg kg(-1) day(-1)) was given for 2 weeks following 4 weeks untreated diabetes. Corpus cavernosum were isolated in organ baths for measurement of agonist or electrical stimulation-evoked nerve-mediated tension responses. Maximum nitrergic nerve-mediated relaxation of phenylephrine-precontracted cavernosum was approximately 35% reduced by diabetes; FeTMPyP treatment reversed this deficit by 45%. The concentration response-curve for nitric oxide-mediated endothelium-dependent relaxation to acetylcholine was attenuated by diabetes; FeTMPyP restored the deficit to the nondiabetic range. Sensitivity (EC50) to the nitric oxide donor, sodium nitroprusside, was reduced by approximately 0.56 log10 M units in diabetes; however, FeTMPyP treatment failed to significantly reverse this deficit. Therefore, the peroxynitrite mechanism contributes to nitric oxide-dependent diabetic autonomic neuropathy and vasculopathy and may be a potential target for clinical trials using peroxynitrite decomposition catalysts.

Effects of pravastatin on progression of glucose intolerance and cardiovascular remodeling in a type II diabetes model

OBJECTIVES

We examined the effects of early treatment with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor pravastatin on the progression of glucose intolerance and cardiovascular remodeling in a model of spontaneously developing type II diabetes mellitus (DM), the Otsuka Long-Evans Tokushima Fatty (OLETF) rats.

BACKGROUND

Clinical trials showed that pravastatin prevented new-onset DM in hypercholesterolemic patients, and that it was effective in prevention of cardiovascular events in diabetics.

METHODS

The OLETF rats were treated with pravastatin (100 mg/kg/day) from 5 weeks of age and compared with age-matched untreated OLETF rats and normal Long-Evans Tokushima Otsuka (LETO) rats on serial oral glucose tolerance tests (OGTT) and Doppler echocardiography and on histopathological/biochemical analyses of the heart at 30 weeks.

RESULTS

The OGTT revealed that 40% and 89% of untreated OLETF rats were diabetic at 20 and 30 weeks, respectively, but 0% and only 30%, respectively, were diabetic in the treated OLETF. Left ventricular diastolic function was found impaired from 20 weeks in untreated OLETF but remained normal in the treated-OLETF. The wall-to-lumen ratio and perivascular fibrosis of coronary arteries were increased in untreated-OLETF but were limited in the treated-OLETF at 30 weeks. Moreover, cardiac expressions of a fibrogenic growth factor, transforming growth factor-beta1 (TGF-beta1), and a proinflammatory chemokine, monocyte chemoattractant protein-1 (MCP-1), were increased in untreated-OLETF. However, in the treated-OLETF, overexpressions of TGF-beta1 and MCP-1 were attenuated, which was associated with overexpression of endothelial nitric oxide synthase (eNOS) (2.5-fold of control LETO).

CONCLUSIONS

Early pravastatin treatment prevented cardiovascular remodeling in the spontaneous DM model by retarding the progression of glucose intolerance, overexpressing cardiac eNOS, and inhibiting overexpressions of fibrogenic/proinflammatory cytokines.

Association between different lipid-lowering treatment strategies and blood pressure control in the Brisighella Heart Study

BACKGROUND

Small studies have suggested that lipid-lowering strategies, and particularly statins, could influence blood pressure (BP) control. The aim of the present study was to evaluate the effect of different lipid-lowering strategies on BP control of subjects with hypercholesterolemia who were enrolled in the prospective, population-based, longitudinal Brisighella Heart Study.

METHODS

A total of 1356 subjects with total cholesterol levels >or=239 mg/dL were randomly treated for 5 years (1988-1993) with 1 of these lipid-lowering regimens: low-fat diet, cholestyramine, gemfibrozil, or simvastatin. Participants were divided at baseline into 4 quartiles according to systolic BP level and examined for the percent change in systolic and diastolic BP during the 5 years of treatment.

RESULTS

A significant decrease in BP was observed in the 2 upper quartiles of systolic BP (>or=140 mm Hg) and was greater in subjects treated with cholesterol-lowering drugs who also had a greater reduction in plasma levels of low-density lipoprotein cholesterol. The BP decrease was greater in patients treated with statin drugs and, among those treated with antihypertensive drugs, in subjects in the fourth quartile.

CONCLUSION

The use of lipid-lowering measures could significantly improve BP control in subjects with both hypercholesterolemia and hypertension. The reduction in BP seems to be enhanced in subjects treated with statins.

Nontraditional risk factors for cardiovascular disease in diabetes

People with type 2 diabetes are disproportionately affected by cardiovascular disease (CVD), compared with those without diabetes. Traditional risk factors do not fully explain this excess risk, and other "nontraditional" risk factors may be important. This review will highlight the importance of nontraditional risk factors for CVD in the setting of type 2 diabetes and discuss their role in the pathogenesis of the excess CVD morbidity and mortality in these patients. We will also discuss the impact of various therapies used in patients with diabetes on nontraditional risk factors.

The Role of Exercise in the Treatment of Cardiovascular Disease Associated with Type 2 Diabetes Mellitus

The role of exercise training in the prevention and treatment of type 2 diabetes mellitus has been studied extensively over the past two decades. Although the primary treatment aim for patients with type 2 diabetes is metabolic control, the morbidity and mortality associated with the disease is more a function of cardiovascular disease. As exercise is associated with favourable reductions in the risk for cardiovascular disease in other high-risk populations, here we explore the role of exercise in the treatment of cardiovascular maladaptations associated with type 2 diabetes. The cardiovascular adaptation to type 2 diabetes is characterised by hypertrophy, stiffening and loss of functional reserve. Clinically, the cardiovascular adaptations to the diabetic state are associated with an increased risk for cardiovascular disease. Functionally, these adaptations have been shown to contribute to a reduced exercise capacity, which may explain the reduced cardiovascular fitness observed in this population. Exercise training is associated with improved exercise capacity in various populations, including type 2 diabetes. Several structural and functional adaptations within the cardiovascular system following exercise training could explain these findings, such as reductions in ventricular and vascular structural hypertrophy and compliance coupled with increased functional reserve. Although these cardiovascular adaptations to aerobic exercise training have been well documented in older populations with similar decrements in cardiovascular fitness and function, they have yet to be examined in patients with type 2 diabetes. For this reason, we contend that exercise training may be an excellent therapeutic adjunct in the treatment of diabetic cardiovascular disease.

All hydrophobic HMG-CoA reductase inhibitors induce apoptotic death in rat pulmonary vein endothelial cells

3-Hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitors (statins) are effective in patients with hypercholesterolemia to reduce risk of cardiovascular diseases, because of not only their lowering cholesterol effects but also their pleiotropic effects, such as improvement of endothelial cell dysfunction. On the other hand, statins prevent cell proliferation of various cells, including endothelial cells. We examined effects of all statins available at present on the viability of cultured rat pulmonary vein endothelial cells. Lovastatin, simvastatin, atorvastatin, fluvastatin and cerivastatin, which are hydrophobic statins, markedly reduced cell viability associated with DNA fragmentation, DNA laddering and activation of caspase-3, suggesting apoptotic cell death. Pravastatin, which is a hydrophilic statin, however, did not induce cell apoptosis. Apoptosis induced by hydrophobic statins was associated with activation of apoptosis-related intracellular signal transduction systems; attenuation of localization of RhoA to the membrane, induction of Rac1, and increase in phosphorylation of c-Jun N-terminal kinase and c-Jun. Endothelial cell apoptosis is underlying the improvement of the endothelial dysfunction with hydrophobic statins.

Insulin resistance and endothelial dysfunction

Insulin has multiple metabolic actions, including effects on blood vessels. Insulin normally increases blood flow by a mechanism which involves generation of nitric oxide (NO) via the arginine-NO pathway. Although insulin itself is a weak and physiologically unimportant vasodilatator, it appears to markedly potentiate endothelium-dependent vasodilatation. Therefore, anything that impairs insulin action in endothelial cells can be expected to be associated with endothelial dysfunction, i.e. loss of NO bioactivity in the vessel wall. Consistent with the idea that insulin resistance and endothelial dysfunction frequently coexist, all insulin-resistant conditions examined to date have been associated with endothelial dysfunction. However, the latter can also be caused by factors other than insulin resistance-such as a high concentration of low-density lipoprotein (LDL) cholesterol. Therapies which reverse insulin resistance-such as exercise, insulin and inhibitors of the renin-angiotensin-aldosterone (RAA) axis-also reverse endothelial dysfunction, which may thus be an inherent feature of insulin resistance.

Effects of rosuvastatin on nitric oxide-dependent function in aorta and corpus cavernosum of diabetic mice: relationship to cholesterol biosynthesis pathway inhibition and lipid lowering

Elevated plasma lipids contribute to neurovascular dysfunction in diabetes. Statins have lipid-lowering properties and can modulate endothelial nitric oxide (NO) bioavailability. The aim was to assess the impact of these factors on autonomic nitrergic nerve and endothelial function. Thus, the effects of diabetes and treatment with the HMG-CoA reductase inhibitor rosuvastatin (RSV) were examined on corpus cavernosum and aorta from streptozotocin-induced diabetic mice in a 4-week prevention study and a 2-week intervention study, following 4 weeks of untreated diabetes. Cotreatment with mevalonate was used to assess the dependence of RSV's effects on HMG-CoA reductase blockade. Diabetes caused a 25% reduction in NO-mediated endothelium-dependent relaxation to acetylcholine for aorta and cavernosum. Relaxations of cavernosum were in the nondiabetic range following prevention or reversal treatment. The aortic deficit was completely prevented and 60% reversed by RSV. Maximum NO-dependent nonadrenergic, noncholinergic nerve-mediated relaxations of cavernosum were reduced 25-33% by diabetes. RSV treatment prevented 75% and reversed 71% of this diabetic deficit. Cotreatment with mevalonate inhibited the beneficial actions of RSV on aorta and cavernosum. Total plasma cholesterol was unaltered by diabetes or treatment. Thus, RSV corrected defective NO-mediated nerve and vascular function in diabetic mice independent of cholesterol lowering but via effects dependent on cholesterol biosynthesis pathway inhibition.

[The statins: new properties]]

The comparison of major statin trials with trials using either cholestyramine or ileal bypass has suggested that the reduction in coronary heart disease events for those patients receiving statin therapy largely result from their low density lipoprotein (LDL)-cholesterol lowering action. LDL-cholesterol lowering has several physiological consequences, including plaque stabilisation with a decrease in the inflammatory process, slowing of plaque progression, and improvement of endothelial function, as evidenced by the measurement of endothelial-dependent vasorelaxation in response to hyperhaemia or acetylcholine infusion. Statins lower C-reactive protein without any consistent effect on the other inflammation acute phase proteins. The cause and consequences of this effect are still debated. In order to explain why some statins can prevent coronary events within a few months, a direct effect of this therapy on thrombosis has also been advocated; however, the evaluation of statin antithrombotic effects in humans has produced conflicting results. By inhibiting L-mevalonic acid synthesis, statins also prevent the farnelysation of small-GTP binding proteins such as Rho and Ras. In vitro, and in animal models, the inhibition of Rho with statins results in a decrease in endothelial nitric oxide production, an inhibition of leucocyte adhesion on endothelium, decrease in PPAR alpha activation and high density lipoprotein (HDL) production by the hepatocyte, decrease in Ca2+ stores in vascular smooth cells, and a stimulation of vascular smooth muscle cell apoptosis. However, most of these effects were obtained with high statin concentrations. Further evidence is needed before a full assessment of the clinical importance of isoprenylation blockage with therapeutic concentrations of statins in humans can be made.

Measurement of subclinical atherosclerosis: beyond risk factor assessment

PURPOSE OF REVIEW

Assessment of subclinical atherosclerosis using the current available noninvasive imaging modalities holds promise for individual cardiovascular risk management and monitoring efficacy of therapeutic interventions (i.e. surrogate end-points). The present review addresses benefits and limitations of flow-mediated dilatation, intima-media thickness, electron-beam computed tomography and magnetic resonance coronary angiography.

RECENT FINDINGS

Both carotid intima-media thickness and peripheral flow-mediated dilatation correlate inversely with cardiovascular risk factors and coronary artery disease. They have been shown to carry predictive value for future cardiovascular events, but clinical application of both intima-media thickness and flow-mediated dilatation demands further methodological maturation of these techniques. Intima thickening has been successfully targeted in numerous intervention trials, but determination of an explicit threshold value beyond which cardiovascular risk significantly increases will facilitate its utility as a routine clinical tool. Electron-beam computed tomography can accurately detect and quantify coronary artery calcification (an established marker of the total coronary plaque burden). However, lack of evidence of its additional predictive power for future coronary events warrants for further research. Finally, magnetic resonance coronary angiography appears to be a promising technique, integrating both functional and anatomical aspects of coronary artery disease. Properly designed studies are needed to determine its value in clinical practice.

SUMMARY

Various noninvasive imaging techniques have recently emerged that may find applications in clinical research. However, before widespread clinical utilization, further technical refinement of all of the cited imaging modalities is mandatory. It will be a challenge over the coming few years to clarify whether improvements in surrogate end-points can directly be translated into improved outcomes.

Interactions between hypercholesterolemia and hypertension: implications for therapy

PURPOSE OF THE REVIEW

The purpose of the present review is to summarize the available information that supports the therapeutic role for the concomitant and aggressive management of hypercholesterolemia and hypertension.

RECENT FINDINGS

A concomitant management of hypertension and high-plasma cholesterol has been suggested to significantly reduce the extent of cardiovascular complications. Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) have been demonstrated to be very effective in the treatment of patients with hypercholesterolemia where they reduce the rate of coronary and cerebrovascular complications. This benefit is largely extended to the hypertensive population. Very recently some studies have demonstrated the capacity of statins to improve blood pressure control in patients with hypertension and this effect, which has not been demonstrated for the other lipid-lowering drugs, could be very important in the clinical management of overall cardiovascular risk.

SUMMARY

These findings confirm that the prevention of cardiovascular diseases should be based on the aggressive treatment of many different risk factors. This is particularly true for patients with hypertension and hypercholesterolemia for whom the negative interaction between risk factors could be effectively managed by an appropriate choice of both antihypertensive and lipid-lowering drugs.