Calcium Channel Blockades Exhibit Anti-Inflammatory and Antioxidative Effects by Augmentation of Endothelial Nitric Oxide Synthase and the Inhibition of Angiotensin Converting Enzyme in the NG-Nitro-L-Arginine Methyl Ester-Induced Hypertensive Rat Aorta: Vasoprotective Effects beyond the Blood Pressure-Lowering Effects of Amlodipine and Manidipine

Causal relationship between antihypertensive drugs and Hashimoto's thyroiditis: a drug-target Mendelian randomization study

Introduction and objectives

Recent studies have indicated a potential association of hypertension with Hashimoto's thyroiditis (HT) and other autoimmune diseases, yet the impact of antihypertensive drugs on HT risk is not well understood.

Methods

We employed a drug-target Mendelian randomization approach to investigate the prolonged impact of 9 classes of antihypertensive medications on HT susceptibility in European and Asian populations. Genetic variants close to or within genes associated with the drug targets and systolic blood pressure (SBP) were utilized to mimic the effects of antihypertensive medications. We focused on drugs linked to a lower risk of coronary artery disease for our main analysis. We gathered genetic data on SBP and HT risk from comprehensive genome-wide association studies available for European and Asian groups. For a supplementary analysis, we used expression quantitative trait loci (eQTLs) related to drug target genes as proxies.

Results

Our analysis revealed that the use of calcium channel blockers (CCBs) is linked to a reduced risk of HT in both European (OR [95% CI]: 0.96 [0.95 to 0.98] per 1 mmHg decrease in SBP; p = 3.51×10-5) and Asian populations (OR [95% CI]: 0.28 [0.12, 0.66]; p = 3.54×10-3). Moreover, genetically mimicking the use of loop diuretics (OR [95% CI]: 0.94 [0.91, 0.97]; p = 3.57×10-5) and thiazide diuretics (0.98 [0.96, 0.99]; p = 3.83×10-3) showed a significant association with a decreased risk of HT only in European population. These outcomes were confirmed when eQTLs were employed to represent the effects of antihypertensive medications.

Conclusion

The study suggests that CCBs and diuretics could potentially reduce the risk of HT in different populations. Additional research is needed to assess the feasibility of repurposing antihypertensive medications for the prevention of HT.

Ca2+ signaling and the Hippo pathway: Intersections in cellular regulation

The Hippo signaling pathway is a master regulator of organ size and tissue homeostasis. Hippo integrates a broad range of cellular signals to regulate numerous processes, such as cell proliferation, differentiation, migration and mechanosensation. Ca2+ is a fundamental second messenger that modulates signaling cascades involved in diverse cellular functions, some of which are also regulated by the Hippo pathway. Studies published over the last five years indicate that Ca2+ can influence core Hippo pathway components. Nevertheless, comprehensive understanding of the crosstalk between Ca2+ signaling and the Hippo pathway, and possible mechanisms through which Ca2+ regulates Hippo, remain to be elucidated. In this review, we summarize the multiple intersections between Ca2+ and the Hippo pathway and address the biological consequences.

A new immune disease: systemic hypertension

Systemic hypertension is the most common medical comorbidity affecting the adult population globally, with multiple associated outcomes including cerebrovascular diseases, cardiovascular diseases, vascular calcification, chronic kidney disease, metabolic syndrome and mortality. Despite advancements in the therapeutic field approximately one in every five adult patients with hypertension is classified as having treatment-resistant hypertension, indicating the need for studies to provide better understanding of the underlying pathophysiology and the need for more therapeutic targets. Recent pre-clinical studies have demonstrated the role of the innate and adaptive immune system including various cell types and cytokines in the pathophysiology of hypertension. Moreover, pre-clinical studies have indicated the potential beneficial effects of immunosuppressant medications in the control of hypertension. Nevertheless, it is unclear whether such pathophysiological mechanisms and therapeutic alternatives are applicable to human subjects, while this area of research is undoubtedly a rapidly growing field.

Pulegone Prevents Hypertension through Activation of Muscarinic Receptors and Cyclooxygenase Pathway in L-NAME-Induced Hypertensive Rats

The current study was designed to determine pulegone's antihypertensive and vasoprotective activity in L-NAME-induced hypertensive rats. Firstly, the hypotensive dose-response relationship of pulegone was evaluated in normotensive anesthetized rats using the invasive method. Secondly, the mechanism involved in hypotensive activity was determined in the presence of pharmacological drugs such as atropine/muscarinic receptor blocker (1 mg/kg), L-NAME/NOS inhibitor (20 mg/kg), and indomethacin/COX inhibitor (5 mg/kg) in anesthetized rats. Furthermore, studies were carried out to assess the preventive effect of pulegone in L-NAME-induced hypertensive rats. Hypertension was induced in rats by administering L-NAME (40 mg/kg) orally for 28 days. Rats were divided into six groups which were treated orally with tween 80 (placebo), captopril (10 mg/kg), and different doses of pulegone (20 mg/kg, 40 mg/kg, and 80 mg/kg). Blood pressure, urine volume, sodium, and body weight were monitored weekly. After 28 days, the effect of pulegone on lipid profile, hepatic markers, antioxidant enzymes, and nitric oxide was estimated from the serum of treated rats. Moreover, plasma mRNA expression of eNOS, ACE, ICAM1, and EDN1 was measured using real-time PCR. Results show that pulegone dose-dependently decreased blood pressure and heart rate in normotensive rats, with the highest effect at 30 mg/kg/i.v. The hypotensive effect of pulegone was reduced in the presence of atropine and indomethacin, whereas L-NAME did not change its hypotensive effect. Concurrent treatment with pulegone for four weeks in L-NAME-treated rats caused a reduction in both systolic blood pressure and heart rate, reversed the reduced levels of serum nitric oxide (NO), and ameliorated lipid profile and oxidative stress markers. Treatment with pulegone also improved the vascular response to acetylcholine. Plasma mRNA expression of eNOS was reduced, whereas ACE, ICAM1, and EDN1 levels were high in the L-NAME group, which was facilitated by pulegone treatment. To conclude, pulegone prevented L-NAME-induced hypertension by demonstrating a hypotensive effect through muscarinic receptors and cyclooxygenase pathway, indicating its use as a potential candidate in managing hypertension.

Renoprotective and therapeutic effects of newly water, ethanol, and butanol ginseng fractions in hypertensive and chronic kidney disease with L-NAME

The present study investigated the protective and treatment effects of different ginseng fractions against L-NAME-induced renal toxicity in rats. The data obtained demonstrated that L-NAME significantly increased creatinine, urea, KIM-1, and lipocalin-2 levels in serum; and also increased renal MDA and eNOS levels compared with the control group. Three bioactive fractions were newly extracted from ginseng, analyzed by GC-MS analysis, and were examined for antimicrobial, prebiotic, and histological activities. All ginseng fractions improved such histological changes, as reflected by significant reductions in creatinine, urea, KIM-1, and LCN-2 levels in serum, and renal MDA and eNOS contents in tissue homogenate. The water ginseng fraction (WGF) has the highest prebiotic index of 4.7 toward Lactobacillus reuteri, and can improve the renal functions more than butanol ginseng fraction (BGF) and ethanol ginseng fraction (EGF). These three ginseng fractions significantly reversed L-NAME-induced depletion in the TNF-α gene expression level. Interestingly, WGF was able to improve the renal functions more than BGF and EGF. L-NAME led to alterations in the histological structure and functions of renal tissue of rats and ginseng supplementation could offer greater protection against these changes. Moreover, the WGF exhibited superior renoprotection properties when compared with the other two fractions: BGF and EGF, and the reference drug losartan.

Lysophosphatidylcholine induces oxidative stress in human endothelial cells via NOX5 activation - implications in atherosclerosis

OBJECTIVE

The mechanisms involved in NOX5 activation in atherosclerotic processes are not completely understood.  This study tested the hypothesis that lysophosphatidylcholine (LPC), a proatherogenic component of oxLDL, induces endothelial calcium influx, which drives NOX5-dependent reactive oxygen species (ROS) production, oxidative stress, and endothelial cell dysfunction.  Approach: Human aortic endothelial cells (HAEC) were stimulated with LPC (10-5 M, for different time points).  Pharmacological inhibition of NOX5 (Melittin, 10-7 M) and NOX5 gene silencing (siRNA) were used to determine the role of NOX5-dependent ROS production in endothelial oxidative stress induced by LPC.  ROS production was determined by lucigenin assay and electron paramagnetic spectroscopy (EPR), calcium transients by Fluo4 fluorimetry, and NOX5 activity and protein expression by pharmacological assays and immunoblotting, respectively.

RESULTS

LPC increased ROS generation in endothelial cells at short (15 min) and long (4 h) stimulation times.  LPC-induced ROS was abolished by a selective NOX5 inhibitor and by NOX5 siRNA. NOX1/4 dual inhibition and selective NOX1 inhibition only decreased ROS generation at 4 h.  LPC increased HAEC intracellular calcium, important for NOX5 activation, and this was blocked by nifedipine and thapsigargin.  Bapta-AM, selective Ca2+ chelator, prevented LPC-induced ROS production.  NOX5 knockdown decreased LPC-induced ICAM-1 mRNA expression and monocyte adhesion to endothelial cells.

CONCLUSION

These results suggest that NOX5, by mechanisms linked to increased intracellular calcium, is key to early LPC-induced endothelial oxidative stress and pro-inflammatory processes.  Since these are essential events in the formation and progression of atherosclerotic lesions, this study highlights an important role for NOX5 in atherosclerosis.

Appraisal of disease-modifying potential of amlodipine as an anti-arthritic agent: new indication for an old drug

Amlodipine, a second-generation calcium channel blocker, exhibits documented anti-inflammatory potential. Thereby, present investigation was accomplished with an aim to explore anti-arthritic potential of amlodipine, giving a second chance to an existing drug. For validation of anti-arthritic potential of amlodipine, some in vitro models comprised of bovine serum albumin- and egg albumin-induced protein denaturation along with membrane stabilization of red blood cell was being conducted. In vivo models comprised of formaldehyde-provoked acute arthritis and CFA-instigated chronic arthritic. Paw edema, arthritic index, body weight alterations, biochemical and hematological parameters, and ankle joint histological and radiographic investigations were appraised. Moreover, RT-PCR was conducted to evaluate the levels of several inflammatory markers. Molecular docking was being conducted targeting TNF-α, IL-1β and IL-6 to establish the correlation between experimental and theoretical results. Amlodipine provides significant protection against denaturation being provoked by heating egg albumin and BSA along with stabilizing membrane of red blood cell, thereby proving in vitro anti-arthritic effect. A significant (p < 0.001) reduction in paw swelling was being observed with amlodipine in case of formaldehyde-instigated arthritis especially at the dose of 20 mg/kg. In case of CFA-provoked arthritis, reduction in paw volume and arthritic score while preservation of body weight loss and normal hematological and biochemical parameters in comparison to arthritic control were being manifested by amlodipine at the dose of 20 mg/kg. Gene expression level of TNF-α, IL-6 and IL-1β was significantly reduced by amlodipine while an increase in expression level of IL-4 and IL-10 was evident in animals treated with piroxicam and amlodipine. Molecular docking analysis demonstrated strong binding interaction of amlodipine with TNF-α, IL-6 and IL-1β thus providing a good correlation between experimental and theoretical results. Thus, current study is suggestive that amlodipine exhibits strong anti-arthritic potential and thus can be considered as a candidate for drug repurposing as anti-arthritic agent.

Hypertension: a new treatment for an old disease? Targeting the immune system

Arterial hypertension represents a serious public health problem, being a major cause of morbidity and mortality worldwide. The availability of many antihypertensive therapeutic strategies still fails to adequately treat around 20% of hypertensive patients, who are considered resistant to conventional treatment. In the pathogenesis of hypertension, immune system mechanisms are activated and both the innate and adaptive immune responses play a crucial role. However, what, when and how the immune system is triggered during hypertension development is still largely undefined. In this context, this review highlights scientific advances in the manipulation of the immune system in order to attenuate hypertension and end-organ damage. Here, we discuss the potential use of immunosuppressants and immunomodulators as pharmacological tools to control the activation of the immune system, by non-specific and specific mechanisms, to treat hypertension and improve end-organ damage. Nevertheless, more clinical trials should be performed with these drugs to establish their therapeutic efficacy, safety and risk-benefit ratio in hypertensive conditions. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Cardiac-specific overexpression of metallothionein attenuates L-NAME-induced myocardial contractile anomalies and apoptosis

Hypertension contributes to the high cardiac morbidity and mortality. Although oxidative stress plays an essential role in hypertensive heart diseases, the mechanism remains elusive. Transgenic mice with cardiac overexpression of metallothionein, a heavy metal‐binding scavenger, were challenged with N^G‐nitro‐L‐arginine methyl ester (L‐NAME) for 14 days prior to measurement of myocardial contractile and intracellular Ca²⁺ anomalies as well as cell signalling mechanisms using Western blot and immunofluorescence analysis. L‐NAME challenge elicited hypertension, macrophage infiltration, oxidative stress, inflammation and cardiac dysfunction manifested as increased proinflammatory macrophage marker F4/80, interleukin‐1β (IL‐1β), intracellular O2- production, LV end systolic and diastolic diameters as well as depressed fractional shortening. L‐NAME treatment reduced mitochondrial membrane potential (MMP), impaired cardiomyocyte contractile and intracellular Ca²⁺ properties as evidenced by suppressed peak shortening, maximal velocity of shortening/relengthening, rise in intracellular Ca²⁺, along with elevated baseline and peak intracellular Ca²⁺. These unfavourable mechanical changes and decreased MMP (except blood pressure and macrophage infiltration) were alleviated by overexpression of metallothionein. Furthermore, the apoptosis markers including BAD, Bax, Caspase 9, Caspase 12 and cleaved Caspase 3 were up‐regulated while the anti‐apoptotic marker Bcl‐2 was decreased by L‐NAME treatment. Metallothionein transgene reversed L‐NAME‐induced changes in Bax, Bcl‐2, BAD phosphorylation, Caspase 9, Caspase 12 and cleaved Caspase 3. Our results suggest that metallothionein protects against L‐NAME‐induced myocardial contractile anomalies in part through inhibition of apoptosis.

Chrysin Pretreatment Improves Angiotensin System, cGMP Concentration in L-NAME Induced Hypertensive Rats

N^ω-nitro-l-arginine methyl ester (L-NAME) is a non-specific nitric oxide (NO) synthase inhibitor, commonly used for the induction of NO-deficient hypertension. The objective of the present study was to investigate the effects of chrysin with flavnoids, on L-NAME-induced hypertensive rats. Methods: An experimental hypertensive animal (180–220 g) model was induced by L-NAME intake on rats. In treatment chrysin was orally administered 25 mg/kg body weight (b.w.). Blood pressure was measured by tail cuff plethysmography system. Cardiac and vascular function was evaluated by Langendorff isolated heart system with Angiotensin II (Ang-II), Hexo oxygenase (HO-1), cyclic guanosine monophosphate (cGMP) concentration in tissues respectively. Rats with hypertension showed an elevated blood pressure (BP), left ventricular functions, ang II, and decreased cGMP concentration of tissues. Treatment of chrysin is reverse to near normal in left ventricular functions, Ang-II, Ho-1 and decreased cGMP concentration of tissues. The antihypertensive effect of chrysin appears to be mediated by a reduction in left ventricular functions, cardiac oxidative stress and Ang-II, an increase in cardiac HO-1, cGMP concentration and a prevention of plasma nitric oxide loss.

Contribution of lectin-like oxidized low-density lipoprotein receptor-1 and LOX-1 modulating compounds to vascular diseases

The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for binding and uptake of oxidized low-density lipoprotein (oxLDL) in endothelial cells. LOX-1 is also expressed in macrophages, smooth muscle cells and platelets. Following internalization of oxLDL, LOX-1 initiates a vicious cycle from activation of pro-inflammatory signaling pathways, thus promoting an increased reactive oxygen species formation and secretion of pro-inflammatory cytokines. LOX-1 plays a pivotal role in the development of endothelial dysfunction, foam cell and advanced lesions formation as well as in myocardial ischemia. Furthermore, it is known that LOX-1 plays a pivotal role in mitochondrial DNA damage, vascular cell apoptosis, and autophagy. A large number of studies provide evidence of a LOX-1's role in endothelial dysfunction, hypertension, diabetes, and obesity. In addition, novel insights into LOX-1 ligands and the activated signaling pathways have been gained. Recent studies have shown an interaction of LOX-1 with microRNA's, thus providing novel tools to regulate LOX-1 function. Because LOX-1 is increased in atherosclerotic plaques and contributes to endothelial dysfunction, several compounds were tested in vivo and in vitro to modulate the LOX-1 expression in therapeutic approaches.

Parkia speciosa empty pod prevents hypertension and cardiac damage in rats given N(G)-nitro-l-arginine methyl ester

Parkia speciosa Hassk is a plant found abundantly in Southeast Asia region. Its seeds with or without pods and roots have been used in traditional medicine in this region to treat hypertension. Therefore, we aimed to investigate the potential effect of the plant empty pod extract on hypertension development and changes in heart induced by N(G)-nitro-l-arginine methyl ester (l-NAME) administration in rats. Twenty-four male Sprague Dawley rats were divided into four groups. Groups 1 to 3 were given l-NAME (25mg/kg, intraperitoneally) for 8 weeks. Groups 2 and 3 were also given Parkia speciosa empty pods methanolic extract (800mg/kg, orally) and nicardipine (3mg/kg, orally), concurrently with l-NAME. The last group served as the control. l-NAME reduced plasma nitric oxide level and therefore, increased systolic blood pressure, angiotensin-converting enzyme and NADPH oxidase activities as well as lipid peroxidation in the heart. Parkia speciosa extract and nicardipine treatments had significantly prevented the elevations of blood pressure, angiotensin-converting enzyme, NADPH oxidase activities and lipid peroxidation in the heart induced by the l-NAME. Parkia speciosa extract but not nicardipine prevented the reduction in plasma nitric oxide level caused by l-NAME. In conclusion, Parkia speciosa empty pods methanolic extract has a potential to prevent the development of hypertension possibly by preventing the loss of plasma nitric oxide, as well as has cardioprotective effects by reducing angiotensin-converting enzyme activity and oxidative stress in the heart in rats administered l-NAME.

Antihypertensive methyldopa, labetalol, hydralazine, and clonidine reversed tumour necrosis factor-α inhibited endothelial nitric oxide synthase expression in endothelial-trophoblast cellular networks

Medications used to control hypertension in pregnancy also improve trophoblast and endothelial cellular interaction in vitro. Tumour necrosis factor-α (TNF-α) inhibits trophoblast and endothelial cellular interactions and simultaneously decreases endothelial nitric oxide synthase (eNOS) expression. This study investigated whether antihypertensive medications improved these cellular interactions by modulating eNOS and inducible nitric oxide synthase (iNOS) expression. Human uterine myometrial microvascular endothelial cells (UtMVECs) were pre-incubated with (or without) low dose TNF-α (0.5 ng/mL) or TNF-α plus soluble fms-like tyrosine kinase-1 (sFlt-1) (100 ng/mL). The endothelial cells were cultured on Matrigel. After endothelial cellular networks appeared, trophoblast derived HTR-8/SVneo cells were co-cultured in the presence of clinically relevant doses of methyldopa, labetalol, hydralazine or clonidine for 24 hours. Cells were retrieved from the Matrigel to extract mRNA and eNOS and iNOS expression were examined by quantitative PCR. Methyldopa, labetalol, hydralazine and clonidine reversed the inhibitory effect of TNF-α on eNOS mRNA expression. After pre-incubating endothelial cells with TNF-α and sFlt-1, all the medications except methyldopa lost their effect on eNOS mRNA expression. In the absence of TNF-α, antihypertensive medications did not change eNOS expression. The mRNA expression of iNOS was not affected by TNF-α or any medications. This study shows that selected antihypertensive medications used in the treatment of hypertension in pregnancy increase eNOS expression in vitro when induced by the inflammatory TNF-α. The anti-angiogenic molecule sFlt-1 may antagonise the potential benefit of these medications by interfering with the NOS pathway.

Amlodipine in hypertension: a first-line agent with efficacy for improving blood pressure and patient outcomes

OBJECTIVES

Hypertension is well established as a major risk factor for cardiovascular disease. Although there is undeniable evidence to support the beneficial effects of antihypertensive therapy on morbidity and mortality, adequate blood pressure management still remains suboptimal. Research into the treatment of hypertension has produced a multitude of drug classes with different efficacy profiles. These agents include β-blockers, diuretics, ACE inhibitors, angiotensin receptor blockers and calcium channel blockers. One of the oldest groups of antihypertensives, the calcium channel blockers are a heterogeneous group of medications.

METHODS

This review paper will focus on amlodipine, a dihydropyridine calcium channel blockers, which has been widely used for 2 decades.

RESULTS

Amlodipine has good efficacy and safety, in addition to strong evidence from large randomised controlled trials for cardiovascular event reduction.

CONCLUSIONS

Amlodipine should be considered a first-line antihypertensive agent.

Mechanisms of the antihypertensive effects of Nigella sativa oil in L-NAME-induced hypertensive rats

OBJECTIVES

This study was conducted to determine whether the blood pressure-lowering effect of Nigella sativa might be mediated by its effects on nitric oxide, angiotensin-converting enzyme, heme oxygenase and oxidative stress markers.

METHODS

Twenty-four adult male Sprague-Dawley rats were divided equally into 4 groups. One group served as the control (group 1), whereas the other three groups (groups 2-4) were administered L-NAME (25 mg/kg, intraperitoneally). Groups 3 and 4 were given oral nicardipine daily at a dose of 3 mg/kg and Nigella sativa oil at a dose of 2.5 mg/kg for 8 weeks, respectively, concomitantly with L-NAME administration.

RESULTS

Nigella sativa oil prevented the increase in systolic blood pressure in the L-NAME-treated rats. The blood pressure reduction was associated with a reduction in cardiac lipid peroxidation product, NADPH oxidase, angiotensin-converting enzyme activity and plasma nitric oxide, as well as with an increase in heme oxygenase-1 activity in the heart. The effects of Nigella sativa on blood pressure, lipid peroxidation product, nicotinamide adenine dinucleotide phosphate oxidase and angiotensin-converting enzyme were similar to those of nicardipine. In contrast, L-NAME had opposite effects on lipid peroxidation, angiotensin-converting enzyme and NO.

CONCLUSION

The antihypertensive effect of Nigella sativa oil appears to be mediated by a reduction in cardiac oxidative stress and angiotensin-converting enzyme activity, an increase in cardiac heme oxygenase-1 activity and a prevention of plasma nitric oxide loss. Thus, Nigella sativa oil might be beneficial for controlling hypertension.

Time course of cardiac inflammation during nitric oxide synthase inhibition in SHR: impact of prior transient ACE inhibition

We have previously demonstrated that angiotensin-converting enzyme (ACE) inhibition with enalapril produces persistent effects that protect against future nitric oxide synthase (NOS) inhibitor (L-arginine methyl ester, L-NAME)-induced cardiac dysfunction and outer wall collagen deposition in spontaneously hypertensive rats (SHR). In the present study, we dissect the cytokine/chemokine release profile during NOS inhibition, its correlation to pathological cardiac remodeling and the impact of transient ACE inhibition on these effects. Adult male SHR were treated with enalapril (E+L) or tap water (C+L) for 2 weeks followed by a 2-week washout period. Rats were then subjected to 0, 3, 7 or 10 days of L-NAME treatment. The temporal response to NOS inhibition was evaluated by measuring arterial pressure, cardiac remodeling and cytokine/chemokine levels. L-NAME equivalently increased blood pressure and myocardial and vascular injury in C+L and E+L rats. However, pulse pressure (PP) was only transiently altered in C+L rats. The levels of several inflammatory mediators were increased during L-NAME treatment. However, interleukin-6 (IL-6) and IL-10 and monocyte chemoattractant protein-1 were uniquely increased in C+L hearts; whereas IL-4 and fractalkine were only elevated in E+L hearts. By days 7 and 10 of L-NAME treatment, there was a significant increase in the cardiac density of macrophages and proliferating cells, respectively only in C+L rats. Although myocardial injury was similar in both treatment groups, PP was not changed and there was a distinct cardiac chemokine/cytokine signature in rats previously treated with enalapril that may be related to the lack of proliferative response and macrophage infiltration in these hearts.

Reactive oxygen species, vascular Noxs, and hypertension: focus on translational and clinical research

SIGNIFICANCE

Reactive oxygen species (ROS) are signaling molecules that are important in physiological processes, including host defense, aging, and cellular homeostasis. Increased ROS bioavailability and altered redox signaling (oxidative stress) have been implicated in the onset and/or progression of chronic diseases, including hypertension.

RECENT ADVANCES

Although oxidative stress may not be the only cause of hypertension, it amplifies blood pressure elevation in the presence of other pro-hypertensive factors, such as salt loading, activation of the renin-angiotensin-aldosterone system, and sympathetic hyperactivity, at least in experimental models. A major source for ROS in the cardiovascular-renal system is a family of nicotinamide adenine dinucleotide phosphate oxidases (Noxs), including the prototypic Nox2-based Nox, and Nox family members: Nox1, Nox4, and Nox5.

CRITICAL ISSUES

Although extensive experimental data support a role for increased ROS levels and altered redox signaling in the pathogenesis of hypertension, the role in clinical hypertension is unclear, as a direct causative role of ROS in blood pressure elevation has yet to be demonstrated in humans. Nevertheless, what is becoming increasingly evident is that abnormal ROS regulation and aberrant signaling through redox-sensitive pathways are important in the pathophysiological processes which is associated with vascular injury and target-organ damage in hypertension.

FUTURE DIRECTIONS

There is a paucity of clinical information related to the mechanisms of oxidative stress and blood pressure elevation, and a few assays accurately measure ROS directly in patients. Such further ROS research is needed in humans and in the development of adequately validated analytical methods to accurately assess oxidative stress in the clinic.

Blood pressure-lowering effect of dietary (-)-epicatechin administration in L-NAME-treated rats is associated with restored nitric oxide levels

Epidemiological and intervention studies have shown that the intake of certain chocolates or cocoa products decreases blood pressure (BP) in humans. (-)-Epicatechin is the most abundant flavanol present in cocoa seeds and its derived foods. This work investigates the effects of dietary (-)-epicatechin on BP in rats that received N(ω)-nitro-l-arginine methyl ester (L-NAME) for 4 days. (-)-Epicatechin administration prevented the 42mm Hg increase in BP associated with the inhibition of NO production in a dose-dependent manner (0.2-4.0g/kg diet). This BP effect was associated with a reduction in L-NAME-mediated increase in the indexes of oxidative stress (plasma TBARS and GSSG/GSH(2) ratio) and with a restoration of the NO concentration. At the vascular level, none of the treatments modified NOS expression, but (-)-epicatechin administration avoided the L-NAME-mediated decrease in eNOS activity and increase in both superoxide anion production and NOX subunit p47(phox) expression. In summary, (-)-epicatechin was able to prevent the increase in BP and in oxidative stress and restored NO bioavailability. The fact that (-)-epicatechin is present in several plants usually consumed by humans gives the possibility of developing diets rich in those plants or pharmacological strategies using that flavonoid to diminish BP in hypertensive subjects.

Current therapeutic strategies to mitigate the eNOS dysfunction in ischaemic stroke

Impairment of endothelial nitric oxide synthase (eNOS) activity is implicated in the pathogenesis of endothelial dysfunction in many diseases including ischaemic stroke. The modulation of eNOS during and/or following ischaemic injury often represents a futile compensatory mechanism due to a significant decrease in nitric oxide (NO) bioavailability coupled with dramatic increases in the levels of reactive oxygen species that further neutralise NO. However, applications of a number of therapeutic agents alone or in combination have been shown to augment eNOS activity under a variety of pathological conditions by potentiating the expression and/or activity of Akt/eNOS/NO pathway components. The list of these therapeutic agents include NO donors, statins, angiotensin-converting enzyme inhibitors, calcium channel blockers, phosphodiesterase-3 inhibitors, aspirin, dipyridamole and ellagic acid. While most of these compounds exhibit anti-platelet properties and are able to up-regulate eNOS expression in endothelial cells and platelets, others suppress eNOS uncoupling and tetrahydrobiopterin (an eNOS stabiliser) oxidation. As the number of therapeutic molecules that modulate the expression and activity of eNOS increases, further detailed research is required to reveal their mode of action in preventing and/or reversing the endothelial dysfunction.

Increased leukocyte Rho-associated coiled-coil containing protein kinase activity predicts the presence and severity of coronary vasospastic angina

OBJECTIVE

Although inhibition of Rho-associated coiled-coil containing protein kinase (ROCK) has been shown to prevent coronary vasospastic angina (CVA), direct evidence linking ROCK activity and CVA is lacking. Accordingly, we investigated whether ROCK activity is an independent marker for CVA and is altered after treatment with antispastic medications.

METHODS AND RESULTS

We prospectively studied 31 Taiwanese patients who were diagnosed with CVA and 33 control subjects. Subject demographics were recorded, and blood samples were obtained at baseline in all participants and in CVA patients after 3 months of antispastic treatment. Compared with control subjects, leukocyte ROCK activity was greater in CVA patients (136% versus 91%, P<0.001). A cutoff value for leukocyte ROCK activity of 104% predicted the presence of CVA with specificity and sensitivity rates of 88% and 84%, respectively. ROCK activity increased with the severity of CVA (P for trend<0.001). Following 3-month treatment of antispastic agents, leukocyte ROCK activity, high-sensitivity C-reactive protein, and interleukin-6 levels were reduced by 43%, 42% and 27%, respectively (P<0.05 for all).

CONCLUSIONS

Increased levels of leukocyte ROCK activity independently predicted the presence of CVA and correlated with CVA severity. Treatment with antispastic agents substantially reduced the level of leukocyte ROCK activity.

Olmesartan/amlodipine: blood pressure lowering and beyond in special populations

Clinical studies and population-based analyses show that in patients with hypertension, the majority cannot control their blood pressure (BP) by treatment with a single antihypertensive agent. Combining agents from different antihypertensive classes with complementary modes of action significantly increases efficacy and is a treatment strategy recommended by European treatment guidelines, particularly in patients at high cardiovascular risk. The combinations of antihypertensive agents recommended by the European guidelines include an angiotensin receptor blocker (ARB) with a calcium channel blocker (CCB). The single-pill combination formulation of the ARB olmesartan medoxomil plus the CCB amlodipine is an effective and well-tolerated treatment that provides greater blood pressure lowering and control than the component monotherapies and favours compliance by not increasing pill burden. Importantly, the efficacy and tolerability of olmesartan plus amlodipine is not affected by age, gender, hypertension severity, diabetes status, race or body mass index. Additional blood pressure lowering effects are observed with stepwise uptitration of olmesartan plus amlodipine with or without hydrochlorothiazide, with more patients achieving blood pressure goals. In addition, olmesartan plus amlodipine has demonstrated effects beyond BP lowering by showing beneficial effects on markers of inflammation, endothelial dysfunction and oxidative stress, as well as metabolic improvements and a reduction in new-onset diabetes incidence in hypertensive patients with metabolic syndrome.

Vaccination against the angiotensin type 1 receptor for the prevention of L-NAME-induced nephropathy

Previous studies have shown that renin-angiotensin (Ang) system vaccines may be effective for the treatment of hypertension, but their efficacy for the prevention of renal disease is unclear. The aim of this study was to compare the effects of an Ang II type 1 (AT1) receptor vaccine with an Ang II receptor blocker (ARB) and a vasodilator on blood pressure (BP) and renal injury in the L-NAME nephropathy model. Male spontaneously hypertensive rats (SHRs) were divided into six groups and treated transiently with three injections of vehicle or AT1 receptor vaccine (0.1 mg) at age 4, 6 and 8 weeks, or continuously with candesartan cilexetil (0.1 mg kg(-1) per day) or hydralazine hydrochloride (5 mg kg(-1) per day), then administered NG-nitro-L-arginine methyl ester (L-NAME) from age 18 to 21 weeks to induce renal injury. Vaccination against the AT1 receptor caused a significant increase in AT1 receptor titers, and a sustained decrease in BP. L-NAME treatment resulted in a marked increase in proteinuria in the control groups, which was completely suppressed in the AT1 vaccine-treated group, and glomerular injury scores were also significantly decreased. Real-time RT-PCR and immunofluorescence studies revealed increased renin mRNA, and increased glomerular expression of nephrin. Comparable results were seen in rats treated continuously with the ARB candesartan, but not with hydralazine. These results suggest that transient AT1 vaccination is as effective as continuous treatment with ARB, not only for the attenuation of hypertension, but also for the prevention of L-NAME-induced nephropathy in SHR.

Candesartan and amlodipine combination therapy provides powerful vascular protection in stroke-prone spontaneously hypertensive rats

The vascular protective effects of placebo, candesartan (1 mg kg(-1) per day) monotherapy, candesartan (1 mg kg(-1) per day) and amlodipine (1 mg kg(-1) per day) combination therapy, and candesartan (1 mg kg(-1) per day) and hydrochlorothiazide (HCTZ) (10 mg kg(-1) per day) combination therapy for 2 weeks were compared in stroke-prone, spontaneously hypertensive rats. Candesartan monotherapy significantly reduced blood pressure, and both combination therapies were equally and significantly lower than the monotherapy. Acetylcholine-induced vascular relaxation was significantly stronger in all therapeutic groups than in the placebo-treated group. Furthermore, the relaxation was significantly stronger in the candesartan plus amlodipine-treated group than in the candesartan-treated group; however, there was no significant difference between the candesartan- and candesartan plus HCTZ-treated groups. Vascular gene expressions of the NADPH oxidase subunits p22(phox), gp91(phox), NOX1 and NOX4 were significantly attenuated in all therapeutic groups compared with the placebo-treated group, and there were no significant differences among those groups. However, a significant augmentation of vascular superoxide dismutase activity was observed in the candesartan plus amlodipine-treated group, but not in other groups. Malondialdehyde levels in the vascular tissues were significantly attenuated in all therapeutic groups. Compared with the candesartan-treated group, significant attenuation was observed in the candesartan plus amlodipine-treated group, but not in the candesartan plus HCTZ-treated group. Immunohistological analysis showed that areas positive for 4-hydroxy-2-nonenal were significantly reduced in all therapeutic groups, but this reduction was significantly greater for the candesartan plus amlodipine-treated group than for the candesartan-treated group. Thus, candesartan and amlodipine combination therapy could have a powerful protective effect in vascular tissues via the reduction of oxidative stress.

Improving vascular function in hypertension: potential benefits of combination therapy with amlodipine and renin-angiotensin-aldosterone system blockers

Hypertension is characterized by endothelial dysfunction and increased risk for adverse cardiovascular outcomes. In addition to lowering blood pressure, the calcium-channel blocker amlodipine and blockers of the renin-angiotensin-aldosterone system (angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers) may further reduce cardiovascular risk by improving endothelial function when used alone or in combination. In fact, the beneficial effects of the combination of amlodipine and a renin-angiotensin-aldosterone system blocker on endothelial function have been found to be greater than the effect of either drug alone, likely due to additive effects on nitric oxide activity. This review summarizes the observed effects of these agents on endothelial function and the complementary mechanisms by which they act, thus providing rationale (beyond blood pressure benefits) for their use in combination.

Altered expression of sodium transporters and water channels in the submandibular gland of rats treated with nitric oxide synthesis inhibitors

A role of nitric oxide (NO) in the regulation of sodium transporters and water channels in the salivary gland was investigated. Male Sprague-Dawley rats were treated with N^G-nitro-L-arginine methyl ester (L-NAME, 100 mg/L drinking water) for 1 week. The control group was supplied with normal tap water. The expression of Na⁺,K⁺-ATPase, type 2 Na⁺/K⁺/2Cl^- cotransporter (NKCC2), type 1 Na⁺/H⁺ exchanger (NHE1), α-subunit of epithelial sodium transporter (ENaC), and aquaporin-5 (AQP5) and aquaporin-1 (AQP1) proteins were determined in the submandibular gland by Western blot analysis. Following the treatment with L-NAME, the expression of Na⁺,K⁺-ATPase α1-subunit, NKCC2, NHE1, and ENaC α-subunit increased significantly. On the contrary, the expression of AQP5 was significantly decreased, while that of AQP1 was not significantly altered. These findings indicate that the sodium transporters and water channels may be under a tonic regulatory influence of NO in the salivary gland.

Anti-inflammatory drugs and atherosclerosis

PURPOSE OF REVIEW

Inflammation contributes to the formation and progression of atherosclerosis and the therapeutic potential of some anti-inflammatory drugs has been evaluated for possible antiatherosclerotic effects. This review will briefly describe the mechanisms underlying the inflammation-atherosclerosis connection, the effect of various anti-inflammatory therapies on atherosclerotic disease and a sampling of the potential targets and agents under evaluation.

RECENT FINDINGS

Some agents with anti-inflammatory properties appear to have beneficial effects on atherosclerosis or subsequent risk for cardiovascular events, while others have been disappointing. The anti-inflammatory actions of statins have been linked retrospectively with their favorable effects on atherosclerosis progression and clinical outcomes. The cardiovascular safety of COX-2 inhibitors is being assessed prospectively in patients with atherosclerosis. Potential new therapeutic agents targeting other inflammatory mechanisms and oxidative stress are being evaluated in animal models and clinical trials.

SUMMARY

Due to the contributory inflammatory pathways in atherosclerosis, the properties of existing and novel anti-inflammatory agents are being carefully and actively evaluated in cardiovascular disease. Advances in our understanding of both atherosclerosis and the inflammatory contributors may play an important role in future strategies to decrease the incidence of atherosclerotic cardiovascular disease.

Are differences in calcium antagonists relevant across all stages of nephropathy or only proteinuric nephropathy?

PURPOSE OF REVIEW

The main effects of classic calcium antagonists are mediated by the inhibition of L-type calcium channels broadly distributed within the renal vascular bed. Calcium antagonists act predominantly on the afferent arterioles, and dihydropyridines can favour the increase in glomerular hypertension and progression of kidney diseases, in particular when systemic blood pressure remains uncontrolled.

RECENT FINDINGS

Calcium antagonists have been widely used in clinical practice because of their antihypertensive capacity. The prevention of renal damage is a very important aim of antihypertensive therapy. This is particularly so taking into account the high prevalence of chronic kidney disease in the general population. Non-dihydropyridines such as verapamil have been shown to possess an antiproteinuric effect that could be particularly relevant.

SUMMARY

Recent data from clinical trials have confirmed that, in hypertensive patients with preserved renal function or with chronic kidney disease, calcium antagonists are effective antihypertensive drugs to be considered alone or in combination with an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. In those patients presenting with proteinuric kidney disease, non-dihydropyridines could reduce proteinuria to a greater degree than dihydropyridines.

Combination therapy with renin-angiotensin system blockers: Will amlodipine replace hydrochlorothiazide?

Amlodipine is a highly effective and safe antihypertensive dihydropyridine calcium channel blocker. It is even more effective when used in combination with other antihypertensive medications, including hydrochlorothiazide. When antihypertensive calcium channel blockers were first introduced, evidence in the laboratory that they had some natriuretic properties was adduced to suggest that they would be "the diuretics of the 1990s." This turned out not to be the case. Because of its clinical efficacy, amlodipine is frequently used in fixed-dose combination products, but it is not likely to replace hydrochlorothiazide.

Monocyte chemoattractant protein-1 and atherosclerosis: is there room for an additional biomarker?

Atherosclerosis is an inflammatory disease in which several chemokines are implicated. The roles of these molecules extend from the recruitment of circulating inflammatory cells to the activation of inflammatory and pro-thrombotic cascades, which ultimately leads to an atherosclerosis-related event. One of the most studied chemokines is monocyte chemoattractant protein-1 (CCL2), which has been strongly linked to atherosclerosis in both animal and human studies. The higher the expression of either the CCL2 gene or its receptor CCR-2, the higher the likelihood of developing atherosclerosis in genetically-modified animals. Conversely, the deletion of either CCL2 or its receptor is followed by a significant reduction in the development of atherosclerotic plaques. Studies in humans yield controversial results. Most of these studies linked the plasma CCL2 concentration to the occurrence of atherosclerosis or related events; however, this relationship does not seem to be independent of the classical, known risk factors. Currently, there are no suitable analytical tools to reach strong conclusions with respect to the value of plasma CCL2 concentration as a biomarker of atherosclerosis, but experimental evidence suggests that the CCL2/CCR2 pathway should be further explored as a diagnostic, prognostic and therapeutic target.

Benidipine, a dihydropyridine-Ca2+ channel blocker, increases the endothelial differentiation of endothelial progenitor cells in vitro

Benidipine is a dihydropyridine-Ca2+ channel blocker used in the treatment of hypertension and angina pectoris. In the present study, we examined the effects of benidipine on the endothelial differentiation of circulating endothelial progenitor cells (EPCs) using an in vitro culture method. Peripheral blood derived mononuclear cells (PBMCs) containing EPCs were isolated from C57BL/6 mice, and then the cells were cultured on vitronectin/gelatin-coated slide glasses. After 7 days of culture, endothelial cells differentiated from EPCs were identified as adherent cells with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine-labeled acetylated low density lipoprotein (Dil-Ac-LDL) uptake and lectin binding under a fluorescent microscope. Incubation of PBMCs for 7 days with benidipine (0.01-1 micromol/l) significantly increased the number of Dil-Ac-LDL+/fluorescein isothiocyanate-lectin (FITC-Lectin)+ cells. Wortmannin, a phosphoinositide-3 kinase (PI3K) inhibitor, selectively attenuated the effect of benidipine on the endothelial differentiation. In addition, benidipine treatment augmented the phosphorylation of Akt, indicating that the PI3K/Akt pathway contributed, at least in part, to the endothelial differentiation induced by benidipine. These results suggest that the treatment with benidipine may increase the endothelial differentiation of circulating EPCs and contribute to endothelial protection, prevention of cardiovascular disease, and/or an improvement of the prognosis after ischemic damage.

The long-acting Ca2+-channel blocker azelnidipine prevents left ventricular remodeling after myocardial infarction

Long-acting Ca(2+)-channel blockers have been reported to be effective in treating ischemic heart disease. However, their effects on cardiac remodeling after myocardial infarction (MI) are still unclear. We performed this study to examine the effect of azelnidipine on left ventricular (LV) remodeling, including systolic and diastolic dysfunction, in rats with MI. MI was induced by ligation of the left anterior descending artery. The rats were then separated into 3 groups: a sham-operated group (n = 9), untreated MI group (n = 10), and azelnidipine-treated MI group (n = 10). Four weeks after MI, hemodynamic measurements and Doppler echocardiographic assessment were performed. LV weight and LV end-diastolic dimension were significantly higher in the untreated MI group than in the sham-operated group. Azelnidipine significantly prevented the increases in these parameters. Azelnidipine also improved the ejection fraction (42 +/- 3%, P<0.05) and the E wave to A wave ratio (3.2 +/- 0.5, P<0.05), compared with the untreated MI group (31 +/- 3% and 5.3 +/- 0.8, respectively). In conclusion, azelnidipine can prevent LV remodeling and improve systolic and diastolic function after MI. Administration of long-acting Ca(2+)-channel blockers after MI is an effective strategy for treating MI.

Developmental Activity of the Renin-Angiotensin System during the "Critical Period" Modulates Later L-NAME-Induced Hypertension and Renal Injury

The incidence of hypertension and hypertensive renal disease is increasing worldwide, and new strategies to prevent these diseases need to be investigated. The aims of this study were 1) to examine if transient exposure to an angiotensin receptor blocker (ARB) during an early period in hypertension development confers protection against subsequent worsening of hypertension and renal injury induced by the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), and 2) conversely, to examine the effects of transient exposure to angiotensin II (Ang II) during the same period. First, spontaneously hypertensive rats (SHR) were treated transiently from age 3 to 10 weeks with an ARB (candesartan cilexetil), a calcium channel antagonist or a vasodilator, then taken off treatment for 2 months. Administration of L-NAME at age 18 weeks caused severe hypertension and renal injury. However, the rats that had been exposed to the ARB not only had a lower blood pressure, but also failed to show signs of renal injury or increase of oxidative stress. Furthermore, the elevation of components of the renin-angiotensin-aldosterone system was also suppressed in these rats. In the second study, Wistar-Kyoto rats (WKY) and SHR were exposed to Ang II from age 4 to 8 weeks. The follow-up showed that the blood pressures in the WKY remained elevated compared to controls, while the SHR had heightened increases in blood pressure, renal renin mRNA, and urinary 8-hyroxydeoxyguanosine after L-NAME administration. Together, these experiments demonstrate that transient treatment of rats during an early phase in the development of hypertension with an ARB suppresses the renin-angiotensin-aldosterone system and confers long-term protection against subsequent L-NAME-induced renal injury and increases in renal oxidative stress. Conversely, developmental exposure to Ang II during this "critical" period had the opposite effect, predisposing rats to higher blood pressure, renal injury, and oxidative stress after L-NAME administration.

Vascular Angiotensin Type 1 Receptor Expression Is Associated with Vascular Dysfunction, Oxidative Stress and Inflammation in Fructose-Fed Rats

This study determined whether or not oxidative stress and vascular dysfunction in fructose-induced hyperinsulinemic rats are associated with activation of the vascular renin-angiotensin system (RAS). Four groups of rats were used. CONT rats were fed normal rat chow, CONT+CAP were fed normal rat chow and given 500 mg/L captopril in their drinking water, fructose-fed rats (FFR) were fed a high-fructose diet and FFR+CAP were fed the high-fructose diet plus captopril in water. After 8 weeks, the vascular reactivity of mesenteric artery segments was measured. Blood was analyzed for insulin, glucose, hydrogen peroxide and 8-isoprostane. Aortic and heart tissue were used for subjected to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. Systolic blood pressure was significantly higher in FFR (p<0.05), and captopril treatment inhibited the blood pressure increase. Mesenteric artery dose-response curves to acetylcholine were shifted to the right in FFR (p<0.05) and were normal in FFR+CAP. Plasma insulin (p<0.05), hydrogen peroxide (p<0.02) and 8-isoprostane (p<0.05) were increased in FFR. Captopril treatment reducd hydrogen peroxide and 8-isoprostane concentrations. Aortic tissue mRNA expression levels were increased for angiotensin-converting enzyme (ACE, p<0.05), angiotensin type 1 receptor (AT1R, p<0.02), NOX4 (p<0.02) and VCAM-1 (p<0.05) in FFR aortic samples. Captopril treatment reduced AT1R, NOX4 and VCAM-1 expression in FFR to levels not different from CONT. Similar changes in heart tissue mRNA expression for angiotensinogen, AT1R and NOX4 were also observed. These results demonstrate that vascular RAS is upregulated in FFR and support the hypothesis that vascular RAS mediates vascular dysfunction and vascular oxidative stress in FFR.

Regression of atherosclerosis by amlodipine via anti-inflammatory and anti-oxidative stress actions

We examined whether amlodipine, an L-type calcium channel blocker (CCB), has an inhibitory effect on oxidative stress and inflammatory response, and thereby atherosclerosis, in apolipoprotein E-deficient (ApoEKO) mice. Adult male ApoEKO mice (6 weeks of age) were fed a high-cholesterol diet (HCD) for 8 or 10 weeks with or without oral administration of amlodipine (3 mg/kg/day) for 10 weeks or for only the last 2 weeks of the HCD. After HCD feeding, atherosclerotic lesion formation, in situ superoxide production and nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase activity were evaluated in the proximal aorta. The expressions of NADPH oxidase subunits (p47(phox) and rac-1), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) were determined with immunohistochemistry and quantitative real-time reverse-transcription polymerase chain reaction. After 8 to 10 weeks of HCD administration to ApoEKO mice, marked atherosclerotic lesion formation was observed in the proximal aorta. In the atherosclerotic lesion, superoxide production, the expression of NADPH oxidase subunits, and NADPH oxidase activity were enhanced, and the expressions of MCP-1, ICAM-1, and VCAM-1 were increased. These changes were suppressed in mice that were treated with amlodipine for 10 weeks concomitant with HCD administration, with no significant change in blood pressure and plasma cholesterol level. We also observed that treatment with amlodipine for only the last 2 weeks regressed the atherosclerotic lesions with a decrease in oxidative stress and vascular inflammation. Inhibition of the atherosclerotic lesion area and lipid area in the proximal aorta by amlodipine was correlated with its inhibitory actions on oxidative stress, inflammation and the production of adhesive molecules. These results suggest that amlodipine not only inhibits atherosclerotic lesion formation, but also regresses atherosclerosis, and that these effects are at least partly due to inhibition of oxidative stress and inflammatory response.