Prevention of vascular injury by combination of an AT1 receptor blocker, olmesartan, with various calcium antagonists

Involvement of Angiotensin II Type 1 Receptor and Calcium Channel in Vascular Remodeling and Endothelial Dysfunction in Rats with Pressure Overload

Vascular remodeling is an adaptive response to various stimuli, including mechanical forces, inflammatory cytokines and hormones. In the present study, we investigated the role of angiotensin II type 1 receptor (AT1R) and calcium channel in carotid artery remodeling in response to increased biomechanical forces by using the transverse aortic constriction (TAC) rat model. TAC was induced on ten-week-old male Sprague-Dawley rats and these models were treated with AT1R blocker olmesartan (1 mg/kg/day) or/and calcium channel blocker (CCB) amlodipine (0.5 mg/kg/day) for 14 days. After the treatment, the right common carotid artery proximal to the band (RCCA-B) was collected for further assay. Results showed that olmesartan, but not amlodipine, significantly prevented TAC-induced adventitial hyperplasia. Similarly, olmesartan, but not amlodipine, signifcantly prevented vascular infammation, as indicated by increased tumor necrosis factor α (TNF-α) and increased p65 phosphorylation, an indicator of nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) activation in RCCA-B. In contrast, both olmesartan and amlodipine reversed the decreased expression of endothelial nitric oxidase synthase (eNOS) and improved endothelium-dependent vasodilation, whereas combination of olmesartan and amlodipine showed no further synergistic protective effects. These results suggest that AT1R was involved in vascular remodeling and inflammation in response to pressure overload, whereas AT1R and subsequent calcium channel were involved in endothelial dysfunction.

Vascular remodeling: A redox-modulated mechanism of vessel caliber regulation

Vascular remodeling, i.e. whole-vessel structural reshaping, determines lumen caliber in (patho)physiology. Here we review mechanisms underlying vessel remodeling, with emphasis in redox regulation. First, we discuss confusing terminology and focus on strictu sensu remodeling. Second, we propose a mechanobiological remodeling paradigm based on the concept of tensional homeostasis as a setpoint regulator. We first focus on shear-mediated models as prototypes of remodeling closely dominated by highly redox-sensitive endothelial function. More detailed discussions focus on mechanosensors, integrins, extracellular matrix, cytoskeleton and inflammatory pathways as potential of mechanisms potentially coupling tensional homeostasis to redox regulation. Further discussion of remodeling associated with atherosclerosis and injury repair highlights important aspects of redox vascular responses. While neointima formation has not shown consistent responsiveness to antioxidants, vessel remodeling has been more clearly responsive, indicating that despite the multilevel redox signaling pathways, there is a coordinated response of the whole vessel. Among mechanisms that may orchestrate redox pathways, we discuss roles of superoxide dismutase activity and extracellular protein disulfide isomerase. We then discuss redox modulation of aneurysms, a special case of expansive remodeling. We propose that the redox modulation of vascular remodeling may reflect (1) remodeling pathophysiology is dominated by a particularly redox-sensitive cell type, e.g., endothelial cells (2) redox pathways are temporospatially coordinated at an organ level across distinct cellular and acellular structures or (3) the tensional homeostasis setpoint is closely connected to redox signaling. The mechanobiological/redox model discussed here can be a basis for improved understanding of remodeling and helps clarifying mechanisms underlying prevalent hard-to-treat diseases.

[Drug development for cardiorenal disease based on oxidative stress control]

Oxidative stress is a key factor involved in the pathogenesis and progression of cardiovascular disease (CVD) and chronic kidney disease (CKD). Reactive oxygen species (ROS), produced as a result of redox reactions in various cells, have been recognized as key chemical mediators causing cellular damage and organ dysfunction in CVD and CKD. Nifedipine, a well-known calcium channel blocker, is extremely sensitive to light which gets converted to its nitroso analog, nitrosonifedipine (NO-NIF) in the presence of ultraviolet and visible light. The so formed NO-NIF blocks calcium channel quite weakly compared to that of nifedipine. However, we elucidated for the first time that NO-NIF is converted to NO-NIF radical which acquires extremely strong antioxidant property via reaction with unsaturated fatty acid or endothelial cells. We have already reported that NO-NIF reduces the cytotoxicity of cumene hydroperoxide, which hampers the integrity of cell membrane through oxidative stress, in endothelial cells. Additionally, we demonstrated that NO-NIF restored acetylcholine-responsive vascular relaxation and suppressed intercellular adhesion molecule-1 expression in the aorta of N(ω)-nitro-L-arginine methyl ester-treated rats, a model of vascular endothelial dysfunction. Recently, we reported that NO-NIF ameliorates angiotensin II-induced vascular remodeling via antioxidative effects in vivo and in vitro. These observations point towards the plausible, unique role of NO-NIF as a novel antioxidant which improves vascular dysfunction for overcoming CVD and CKD and the same has been highlighted in this review.

Anti-atherogenic effects of the combination therapy with olmesartan and azelnidipine in diabetic apolipoprotein E-deficient mice

Many studies have aimed to identify anti-atherogenic agents in cardiovascular medicine. We have recently demonstrated that the combination therapy with olmesartan (OLM), an angiotensin II receptor blocker, and azelnidipine (AZL), a dihydroprydine calcium-channel blocker, improves endothelial function in diabetic Apolipoprotein-deficient (ApoE(-/-)) mice. In the present study, we examined whether this combination therapy also inhibits atherosclerosis in mice. We used male control and streptozocin-induced diabetic ApoE(-/-) mice. Diabetic ApoE(-/-) mice were orally treated for 5 weeks with vehicle (Untreated), OLM (30 mg/kg/day), AZL (10 mg/kg/day), their combination (OLM+AZL), or hydralazine (HYD, 5 mg/kg/day) as an antihypertensive control. At 5 weeks, systolic blood pressure was significantly elevated in Untreated but was normalized in OLM+AZL and HYD. The atherosclerosis area in the thoracic aorta, perivascular fibrosis and medial thickness of the coronary arteries were increased in Untreated and were ameliorated in OLM+AZL but not in HYD. Staining with a fluorescent probe dihydroethidium showed that production of reactive oxygen species was increased in Untreated, and ameliorated in OLM+AZL. Consistent with these findings, macrophage infiltration in the kidney and the expression of receptor for advanced glycation end-products in the heart, kidney and liver were increased in Untreated and were all ameliorated in OLM+AZL, associated with up-regulation of endothelial NO syntheses (eNOS). In conclusion, the combination therapy with OLM and AZL exerts anti-atherogenic effect in diabetic ApoE(-/-) mice through suppression of oxidative stress and activation of eNOS, independent of its blood pressure-lowering effects. Clinically, this combination therapy may be useful for patients with hypertension, hyperlipidemia and diabetes.

Powerful vascular protection by combining cilnidipine with valsartan in stroke-prone, spontaneously hypertensive rats

Cilnidipine is an L- and N-type calcium channel blocker (CCB), and amlodipine is an L-type CCB. Valsartan (10 mg kg(-1)), valsartan (10 mg kg(-1)) and amlodipine (1 mg kg(-1)), and valsartan (10 mg kg(-1)) and cilnidipine (1 mg kg(-1)) were administered once daily for 2 weeks to stroke-prone, spontaneously hypertensive rats (SHR-SPs). Blood pressure was significantly reduced by valsartan, and it was further reduced by the combination therapies. Vascular endothelial dysfunction was significantly attenuated in all therapeutic groups, and further significant attenuation was observed in the valsartan+cilnidipine-treated group, but not in the valsartan+amlodipine-treated group. Vascular nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit NOX1 gene expression was significantly attenuated in all therapeutic groups, and significantly greater attenuation was observed in the valsartan+cilnidipine-treated group than in the valsartan-treated group. Compared with the valsartan-treated group, the positive areas for 4-hydroxy-2-nonenal were significantly lower only in the valsartan+cilnidipine-treated group. Plasma renin activity was significantly augmented in the valsartan-treated group, and it was significantly attenuated in the valsartan+cilnidipine-treated group. A significant increase in the ratio of plasma angiotensin-(1-7) to angiotensin II was observed only in the valsartan+cilnidipine-treated group. Vascular angiotensin-converting enzyme (ACE) gene expression was significantly attenuated only in the valsartan+cilnidipine-treated group, but ACE2 gene expression was significantly higher in all of the therapeutic groups. Thus, valsartan and cilnidipine combination therapy might have a powerful protective effect in the vascular tissues via increases in the angiotensin-(1-7)/angiotensin II ratio in plasma.

Monocyte chemoattractant protein-1 is associated with silent cerebral infarction in patients on haemodialysis

BACKGROUND

In patients with chronic renal failure undergoing haemodialysis (HD), silent cerebral infarctions (SCI) are associated with high mortality. Levels of monocyte chemoattractant protein-1 (MCP-1) increase with renal dysfunction and may be a novel predictor for cerebrovascular events. We tested the hypothesis that increased MCP-1 concentration correlate with the occurrence of SCI in HD patients.

METHODS

Using cranial magnetic resonance imaging (MRI) findings, 52 Japanese patients undergoing HD were divided into two groups: with SCI (61 ± 7 years, mean ± SD, n= 28) and without SCI (60 ± 6 years, n= 24). The gender, metabolic profiles and MCP-1 concentration were compared between the two groups.

RESULTS

The level of MCP-1 was higher in the with-SCI group than in the without-SCI group (P < 0.0001). The proportion of smokers was higher in the with-SCI group (P < 0.05) than in the without-SCI group. Plasma level of high-density lipoprotein cholesterol was lower, while uric acid level was higher, in the with-SCI group (P < 0.05 and P < 0.05 respectively) compared to the without-SCI group. Multiple logistic regression analysis identified MCP-1 level as being significantly associated with the presence of SCI (odds ratio 1.48, 95% confidence interval = 1.10-5.75, P < 0.0001).

CONCLUSIONS

This study indicates that patients with chronic renal failure who are maintained on HD exhibit an increased prevalence of SCI, and that MCP-1 is significantly associated with the presence of SCI in HD patients.

Differential Effects in Cardiovascular Markers between High-Dose Angiotensin II Receptor Blocker Monotherapy and Combination Therapy of ARB with Calcium Channel Blocker in Hypertension (DEAR Trial)

Background/Aims. Arterial stiffness is an independent risk factor for cardiovascular morbidity and mortality. This study was conducted to determine the effect of olmesartan (OLM) and azelnidipine (AZL) on arterial stiffness using the cardio-ankle vascular index (CAVI), which is a novel blood pressure (BP)-independent marker for arterial stiffness in hypertensive patients. Methods. Fifty-two consecutive hypertensive patients were randomly assigned either to a group treated with OLM monotherapy or to a group treated with OLM and AZL combination therapy. Clinical and biological parameters were measured before and 12 months after the start of this study. Results. Both therapies significantly and similarly reduced BP, augmentation index, and plasma aldosterone levels. The combination therapy significantly decreased CAVI and serum low-density lipoprotein (LDL-C) levels and these reductions were significantly greater than those produced with monotherapy. No significant differences in metabolic parameters were observed between the two therapies. Conclusion. The combination therapy with OLM and AZL had beneficial effects on arterial stiffness assessed by CAVI, LDL-C, and metabolism, despite the similar BP reduction, compared with OLM monotherapy. Since these markers are known to influence the future risk of cardiovascular events, combination therapy with OLM and AZL could be a useful choice for treating hypertensive patients.

Nifedipine inhibits vascular smooth muscle cell proliferation and reactive oxygen species production through AMP-activated protein kinase signaling pathway

The dihydropyridine calcium channel blocker nifedipine induces specific pharmacological effects by binding to L-type calcium channels, which results in a reduced calcium influx in vascular smooth muscle cells (VSMCs) and is currently employed in antihypertensive drug. Dihydropyridine calcium channel blocker is reported to reduce oxidative stress and exhibits anti-proliferative effect in VSMCs. VSMCs are useful in the study of atherosclerosis because they show cell proliferation and reactive oxygen species (ROS) production with growth factor. To determine the mechanisms involved in these effects, we investigated the influence of nifedipine-induced AMP-activated protein kinase (AMPK) activation on VSMC proliferation and ROS production by using rat aortic VSMCs in vitro and in vivo. Nifedipine induced phosphorylation of AMPK in a dose-and time-dependent manner, and inhibited rat VSMC proliferation and ROS production following stimulation with 15% fetal bovine serum (FBS). Nifedipine also blocked the FBS-stimulated cell cycle progression through the G0/G1 arrest. Compound C, a specific inhibitor of AMPK, or AMPK siRNA reduced the nifedipine-mediated inhibition of VSMC proliferation. As an upstream kinase, LKB1 is required for nifedipine-induced AMPK activation in VSMCs. 7 days oral administration of 1 mg/kg nifedipine resulted in activation of LKB1 and AMPK in vivo. These data suggest that nifedipine suppress the VSMC proliferation and ROS production via activating LKB1-AMPK pathway.

Inflammation and therapy for hypertension

It is currently accepted that hypertension, atherosclerosis, and diabetes are disorders with subtle or overt activation of inflammatory mediators. Therefore, it has become increasingly important to ascertain whether current antihypertensive drug families have proinflammatory or anti-inflammatory actions that modify the outcomes of their hemodynamic effects on blood pressure. We review the current state of knowledge about the effects of the major classes of available antihypertensive agents on inflammation and speculate on the possible contribution of these effects to observations in clinical trials. We suggest that a strategy of drug development specifically addressing inflammation in hypertension may provide increased benefit in terms of target organ damage, and we describe some examples of these promising developments.

Temporary treatment with AT1 receptor blocker, valsartan, from early stage of hypertension prevented vascular remodeling

BACKGROUND

The present study examined the inhibitory action of temporary treatment with an angiotensin type 1 (AT(1)) receptor blocker (ARB) on vascular remodeling using hypertensive mice with overexpression of the human renin (hRN) and angiotensinogen (hANG) genes.

METHODS

hRN/hANG transgenic mice (hRN/hANG-Tg) were treated with an ARB, valsartan, from 4 weeks of age. In some mice, valsartan treatment was stopped at 8 weeks of age (temporary treatment). Inflammatory vascular injury was induced by polyethylene-cuff placement around the femoral artery at the age of 10 weeks.

RESULTS

Compared with wild-type (WT) mice, hRN/hANG-Tg showed higher blood pressure (BP) and enhancement of oxidative stress and medial thickening even before cuff placement. Inflammatory vascular remodeling and oxidative stress after cuff placement were further enhanced in hRN/hANG-Tg. Temporary treatment with valsartan continuously lowered BP even after cessation of administration, and inhibited these changes. In contrast, administration of hydralazine lowered BP to a similar level to that with valsartan, but did not inhibit medial thickening and inflammatory vascular remodeling. In contrast to the valsartan treatment, BP immediately increased to the untreated level after cessation of hydralazine.

CONCLUSIONS

These results indicate that temporary ARB treatment leads to prolonged effect of BP lowering and prevents vascular remodeling in hypertensive mice induced by activation of the human renin-angiotensin system. The inhibitory action of valsartan is not due to the BP lowering but is at least in part due to a decrease in oxidative stress and inflammation.

Urinary albumin excretion during angiotensin II receptor blockade: comparison of combination treatment with a diuretic or a calcium-channel blocker

BACKGROUND

We aimed to test the hypothesis that the angiotensin II receptor blocker (ARB)/diuretic combination decreases the urinary albumin/creatinine ratio (UACR) to a greater extent than treatment with the ARB/calcium-channel blocker (CCB) combination through a mechanism related to a greater reduction of sleep blood pressure (BP).

METHODS

We conducted a prospective, randomized, open-label, blinded end-point trial in hypertensive patients. Patients received olmesartan monotherapy for 12 weeks, followed by an additional use of hydrochlorothiazide (HCTZ) (n = 104) or azelnidipine (n = 103) for 24 weeks after randomization. The measurements of central and ambulatory BP, and laboratory tests were performed at baseline and the end of the study.

RESULTS

The adjusted percent reduction in UACR in the olmesartan/HCTZ group was significantly greater than that in the olmesartan/azelnidipine group (-43.2 vs. -24.0%, P = 0.0014), although the olmesartan/azelnidipine group showed greater decreases in central systolic BP (SBP; P = 0.04), oxidative stress (urinary 8-isoprostane; P = 0.02), inflammation (high-sensitivity C-reactive protein; P = 0.04), and insulin resistance (the homeostasis model assessment insulin resistance index (HOMA(IR)); P < 0.001) than the olmesartan/HCTZ group. In multivariate regression analyses, the significant determinants of change in UACR in the olmesartan/HCTZ group were changes in sleep SBP (P < 0.001), central SBP (P = 0.01), estimated glomerular filtration rate (eGFR) (P = 0.02), and HOMA(IR) (P = 0.03), and those in the olmesartan/azelnidipine group were changes in central SBP (P = 0.001) and urinary 8-isoprostane (P = 0.02).

CONCLUSIONS

These data showed that the ARB/diuretic combination decreased UACR significantly more than the ARB/CCB combination, and this decrease in UACR was associated with a greater magnitude reduction in sleep SBP.

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.

Combination therapy with olmesartan and azelnidipine improves EDHF-mediated responses in diabetic apolipoprotein E-deficient mice

BACKGROUND

The endothelium modulates vascular tone by synthesizing and releasing several vasodilating factors, including vasodilator prostaglandins, nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). In the present study, we examined whether an angiotensin-receptor blocker, a calcium-channel blocker or their combination improved EDHF-mediated responses in diabetic apolipoprotein E-deficient (ApoE(-/-)) mice.

METHODS AND RESULTS

We used male C57BL/6N (control) and streptozocin-induced diabetic ApoE(-/-) mice. The diabetic ApoE(-/-) mice were administered oral vehicle (untreated), olmesartan (OLM, 30 mgxkg(-1)xday(-1)), azelnidipine (AZL, 10 mgxkg(-1)xday(-1)), their combination (OLM + AZL), or hydralazine (HYD 5 mgxkg(-1)xday(-1)) for 5 weeks. In the untreated group, systolic blood pressure was significantly higher and both EDHF-mediated relaxation and endothelium-dependent hyperpolarization were markedly reduced as compared with the control group. Although EDHF-mediated relaxation was not significantly improved in the HYD, OLM and AZL groups, it was significantly improved in the OLM + AZL group, as was also the case with phosphorylation of Akt and endothelial NO synthase (eNOS). In contrast, the endothelium-independent relaxation response to sodium nitroprusside or NS-1619 (a direct opener of K(Ca) channels) was unaltered in any group.

CONCLUSIONS

OLM + AZL may improve the severely impaired EDHF-mediated responses in diabetic ApoE(-/-) mice, in which activation of the endothelial Akt - eNOS pathway may be involved.

Should diuretics always be included as initial antihypertensive management in early-stage CKD?

PURPOSE OF REVIEW

This review focuses on the need for combined antihypertensive therapy drugs in patients with chronic kidney disease and the relevance of diuretics.

RECENT FINDINGS

Chronic kidney disease is a high-risk situation characterized by the presence of volume overload-related hypertension, micro/macroalbuminuria and other traditional and nontraditional risk factors. To achieve the blood pressure goal in these patients, combined antihypertensive therapy (including diuretics) is usually required.

SUMMARY

Extracellular volume expansion is an important, if not the most important, contributing factor to hypertension seen in chronic kidney disease. Protection against progression of renal dysfunction has two main requirements: strict blood pressure control and lowering proteinuria to values as near to normal as possible. Diuretics have been a useful tool to manage volume overload and to achieve strict blood pressure control in patients with chronic kidney disease. Albeit other blood pressure-lowering agents offer additional favorable effects independently of blood pressure changes, diuretics will continue to be used in these patients.