Angiotensin II receptor blockade reduces salt sensitivity of blood pressure through restoration of renal nitric oxide synthesis in patients with diabetic nephropathy

INTRODUCTION

We have previously demonstrated the increased salt sensitivity of blood pressure (BP) in diabetic patients with early nephropathy. Here, we examined the effects of an angiotensin II receptor blocker (ARB) on salt sensitivity and renal oxidative stress or nitric oxide (NO) in those patients.

PATIENTS AND METHODS

Type 2 diabetic patients with (n = 6) and without (n = 6) microalbuminuria were studied on a high-salt diet for one week and on a salt-restricted diet for one week. The study was repeated in the patients with microalbuminuria during treatment with an ARB, valsartan (80 mg/day). Salt sensitivity was assessed from the BP/sodium excretion curve. Urinary excretion rates of NOx, 8-hydroxy-2-deoxyguanosine as a marker of oxidative stress, and plasma tetrahydrobiopterin as a cofactor for NO synthase were measured.

RESULTS

Compared with diabetic patients without microalbuminuria, patients with microalbuminuria showed greater salt sensitivity and lower urinary excretion of NOx. In the patients with microalbuminuria, treatment with valsartan reduced salt sensitivity in association with increased NOx excretion, reduced 8-hydroxy-2,-deoxyguanosine excretion, and increased plasma tetrahydrobiopterin levels.

CONCLUSIONS

These data support the hypothesis that ARBs reduce the salt sensitivity of BP by decreasing renal oxidative stress and restoring NO activity in diabetic patients with microalbuminuria.

Antihypertensive medication use is associated with increased organ system involvement and hospitalization in emergency department patients with anaphylaxis

BACKGROUND

Risk factors for increased anaphylaxis severity are poorly understood. Angiotensin-converting enzyme (ACE) inhibitors have been associated with severe anaphylactic reactions in patients with hymenoptera venom allergy. Studies evaluating the association between beta-blockers and severe anaphylaxis have been conflicting.

OBJECTIVE

To evaluate the association between antihypertensive medication use and increased anaphylaxis severity.

METHODS

We included emergency department anaphylaxis patients aged 18 years and older. Markers of severe anaphylaxis were defined as (1) syncope, hypotension, or hypoxia; (2) signs and symptoms involving 3 or more organ systems; and (3) hospitalization. Antihypertensive medications evaluated included beta-blockers, ACE inhibitors, calcium channel blockers, angiotensin receptor blockers, and diuretics. Simple and multiple logistic regression analyses were conducted to estimate the association between antihypertensive medication use and markers of increased anaphylaxis severity.

RESULTS

Among 302 patients with anaphylaxis, 55 (18%) had syncope, hypoxia, or hypotension, 57 (19%) required hospitalization, and 139 (46%) had 3 or more organ system involvement. After adjusting for age, gender, suspected trigger, and preexisting lung disease, beta-blocker, ACE-inhibitor, diuretic, or antihypertensive medication use in aggregate remained associated with both 3 or more organ system involvement and need for hospital admission. The adjusted associations between antihypertensive medication use in aggregate and 3 or more organ system involvement yielded an odds ratio of 2.8 (95% CI, 1.5-5.2; P=.0008) and with hospitalization an odds ratio of 4.0 (95% CI, 1.9-8.4; P=.0001).

CONCLUSIONS

In emergency department anaphylaxis patients, antihypertensive medication use is associated with increased organ system involvement and increased odds of hospital admission, independent of age, gender, suspected trigger, or preexisting lung disease.

Blockade of the renin-angiotensin system and renal tissue oxygenation as measured with BOLD-MRI in patients with type 2 diabetes

AIM

To assess whether blockade of the renin-angiotensin system (RAS), a recognized strategy to prevent the progression of diabetic nephropathy, affects renal tissue oxygenation in type 2 diabetes mellitus (T2DM) patients.

METHODS

Prospective randomized 2-way cross over study; T2DM patients with (micro)albuminuria and/or hypertension underwent blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) at baseline, after one month of enalapril (20 mgqd), and after one month of candesartan (16 mgqd). Each BOLD-MRI was performed before and after the administration of furosemide. The mean R₂* (=1/T₂*) values in the medulla and cortex were calculated, a low R₂* indicating high tissue oxygenation.

RESULTS

Twelve patients (mean age: 60 ± 11 years, eGFR: 62 ± 22 ml/min/1.73 m(2)) completed the study. Neither chronic enalapril nor candesartan intake modified renal cortical or medullary R₂* levels. Furosemide significantly decreased cortical and medullary R₂* levels suggesting a transient increase in renal oxygenation. Medullary R₂* levels correlated positively with urinary sodium excretion and systemic blood pressure, suggesting lower renal oxygenation at higher dietary sodium intake and blood pressure; cortical R₂* levels correlated positively with glycemia and HbA1c.

CONCLUSION

RAS blockade does not seem to increase renal tissue oxygenation in T2DM hypertensive patients. The response to furosemide and the association with 24 h urinary sodium excretion emphasize the crucial role of renal sodium handling as one of the main determinants of renal tissue oxygenation.

Endogenous angiotensin II-induced p44/42 mitogen-activated protein kinase activation mediates sodium appetite but not thirst or neurohypophysial secretion in male rats

The renin-angiotensin-aldosterone system makes a critical contribution to body fluid homeostasis, and abnormalities in this endocrine system have been implicated in certain forms of hypertension. The peptide hormone angiotensin II (AngII) regulates hydromineral homeostasis and blood pressure by acting on both peripheral and brain targets. In the brain, AngII binds to the angiotensin type 1 receptor (AT1R) to stimulate thirst, sodium appetite and both arginine vasopressin (AVP) and oxytocin (OT) secretion. The present study used an experimental model of endogenous AngII to examine the role of p44/42 mitogen-activated protein kinase (MAPK) as a signalling mechanism to mediate these responses. Animals were given a combined treatment of furosemide and a low dose of captopril (furo/cap), comprising a diuretic and an angiotensin-converting enzyme inhibitor, respectively, to elevate endogenous AngII levels in the brain. Furo/cap induced p44/42 MAPK activation in key brain areas that express AT1R, and this effect was reduced with either a centrally administered AT1R antagonist (irbesartan) or a p44/42 MAPK inhibitor (U0126). Additionally, furo/cap treatment elicited water and sodium intake, and irbesartan markedly reduced both of these behaviours. Central injection of U0126 markedly attenuated furo/cap-induced sodium intake but not water intake. Furthermore, p44/42 MAPK signalling was not necessary for either furo/cap- or exogenous AngII-induced AVP or OT release. Taken together, these results indicate that p44/42 MAPK is required for AngII-induced sodium appetite but not thirst or neurohypophysial secretion. This result may allow for the discovery of more specific downstream targets of p44/42 MAPK to curb sodium appetite, known to exacerbate hypertension, at the same time as leaving thirst and neurohypophysial hormone secretion undisturbed.

Concurrent use of diuretics, angiotensin converting enzyme inhibitors, and angiotensin receptor blockers with non-steroidal anti-inflammatory drugs and risk of acute kidney injury: nested case-control study

OBJECTIVES

To assess whether a double therapy combination consisting of diuretics, angiotensin converting enzyme inhibitors, or angiotensin receptor blockers with addition of non-steroidal anti-inflammatory drugs (NSAIDs) and the triple therapy combination of two of the aforementioned antihypertensive drugs to which NSAIDs are added are associated with an increased risk of acute kidney injury.

DESIGN

Retrospective cohort study using nested case-control analysis.

SETTING

General practices contributing data to the UK Clinical Practice Research Datalink linked to the Hospital Episodes Statistics database.

PARTICIPANTS

A cohort of 487,372 users of antihypertensive drugs.

MAIN OUTCOME MEASURES

Rate ratios with 95% confidence intervals of acute kidney injury associated with current use of double and triple therapy combinations of antihypertensive drugs with NSAIDs.

RESULTS

During a mean follow-up of 5.9 (SD 3.4) years, 2215 cases of acute kidney injury were identified (incidence rate 7/10,000 person years). Overall, current use of a double therapy combination containing either diuretics or angiotensin converting enzyme inhibitors or angiotensin receptor blockers with NSAIDs was not associated with an increased rate of acute kidney injury. In contrast, current use of a triple therapy combination was associated with an increased rate of acute kidney injury (rate ratio 1.31, 95% confidence interval 1.12 to 1.53). In secondary analyses, the highest risk was observed in the first 30 days of use (rate ratio 1.82, 1.35 to 2.46).

CONCLUSIONS

A triple therapy combination consisting of diuretics with angiotensin converting enzyme inhibitors or angiotensin receptor blockers and NSAIDs was associated with an increased risk of acute kidney injury. The risk was greatest at the start of treatment. Although antihypertensive drugs have cardiovascular benefits, vigilance may be warranted when they are used concurrently with NSAIDs.

[Gender-related differences in the efficacy of treatment of hypertensive and coronary heart diseases in aged and elderly patients by angiotensin II receptor blockers and angiotensin converting enzyme inhibitors]

The aim of the work was to study hemodynamics and clinical symptoms before and after treatment of arterial hypertension (AH) and coronary heart disease (CHD) using angiotensin II receptor blockers and angiotensin converting enzyme inhibitors depending on the patients' sex. A total of 150 patients with AH and CHD were examined (80 women and 70 men, mean age 70 a 66 yr respectively). Eighty two of them (group 1) were given receptor blockers (losap, losartan, lorista, bloctran) and 63 (group 2) inhibitors (prestarium, noliprel). Effectiveness of treatment was evaluated from the results of 24-hr AP monitoring, daily self-control of AP (as described by Korotkov) and responds to questionnaires. The effectiveness of receptor blockers showed marked gender-specific differences. Specifically, they reduced systolic and diastolic pressure and improved well-being in women. In men, this treatment decreased the frequency of angina attacks, headache, and heart throbs. Enzyme inhibitors caused a greater reduction of diastolic AP in women but less pronounced gender-related changes in dynamics of main AP and ECG parameters than receptor blockers.

[Impact of cardiac drug intake on adaptation to high temperatures in patients with cardiovascular diseases under conditions of the abnormally hot summer of 2010]

AIM

To evaluate the impact of intake of cardiac drugs on adaptation to abnormal heat in patients with cardiovascular diseases (CVD).

SUBJECTS AND METHODS

The study covered 188 patients with CVD, who had visited the Research Dispensary Department in January 2011. General clinical examination, biochemical blood analysis, and electrocardiography were made; the hospital anxiety and depression scale, the visual analog scale, and the questionnaire specially developed for this investigation were used. The authors considered acute myocardial infarction, acute stroke, hospital admission, a medical emergency team call, temporary disability (days), hypertensive crises, and unplanned visits to a doctor as estimated outcomes (endpoints) and the number of undesirable reactions a week during the abnormal heat and from September to December 2010 as a combined endpoint.

RESULTS

There were a larger number of weekly adverse reactions than usual and a reduction in quality of life (QL) during the abnormal heat. Both an increase and a reduction in the dose of cardiac drugs during the abnormal heat were associated with its worse tolerability. The use of angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers (CCB) was an independent factor associated with the smaller number of complications during the abnormal heat. That of diuretics was an independent factor that was associated with a more decrease in QL in elderly patients during the heat. The intake of angiotensin receptor blockers (ARB) or nitrates was an independent factor associated with the larger number of complications during the abnormal heat.

CONCLUSION

The use of ACE inhibitors and CCB is associated with fewer complications during the abnormal heat of 2010. The intake of diuretics in patients over 65 years of age and that of ARB or nitrates was associated with worse heat tolerance.

RU28318, an aldosterone antagonist, in combination with an ACE inhibitor and angiotensin receptor blocker attenuates cardiac dysfunction in diabetes

AIMS

We evaluated the effects of RU28318 (RU), a selective mineralocorticoid receptor (MR) antagonist, Captopril (Capt), an angiotensin converting enzyme inhibitor, and Losartan (Los), an angiotensin receptor blocker, alone or in combination with ischemia/reperfusion- (I/R-) induced cardiac dysfunction in hearts obtained from normal and diabetic rats.

METHODS

Isolated hearts were perfused for 30 min and then subjected to 30 min of global ischemia (I) followed by a period of 30 min of reperfusion (R). Drugs were administered for 30 min either before or after ischemia. Drug regimens tested were RU, Capt, Los, RU + Capt, RU + Los, Capt + Los, and RU + Capt + Los (Triple). Recovery of cardiac hemodynamics was evaluated.

RESULTS

Recovery of cardiac function was up to 5-fold worse in hearts obtained from diabetic animals compared to controls. Treatment with RU was generally better in preventing or reversing ischemia-induced cardiac dysfunction in normal hearts compared to treatment with Capt or Los alone. In diabetic hearts, RU was generally similarly effective as Capt or Los treatment.

CONCLUSIONS

RU treatment locally might be considered as an effective therapy or preventative measure in cardiac I/R injury. Importantly, RU was the most effective at improving -dP/dt (a measure of diastolic function) when administered to diabetic hearts after ischemia.

[Comparative analysis of the combined treatment efficacy of the Chernobyl accident clean-up workers with essential hypertension]

It was shown the results of comparative evaluation of combined treatment in 111 clean-up workers of Chernobyl accident with essential hypertension (EH). This treatment consist of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers in combination with calcium channel blockers and diuretics. The follow-up period lasted 12 months. It was found that combined therapy provides comparable and reliable blood pressure (BP) control during 24-hour, significant reduction of average daily BP, daytime and nighttime BP, an index of time of the BP, BP variability. Despite on achieved target blood pressure level, 4 weeks treatment is not enough for regression of left ventricular hypertrophy (LVH). Significant regress of LVH was found if treatment lasted during a year under the condition that BP remained at the target level. It was revealed the advantage of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers intake combined with a diuretic on regress of left ventricular hypertrophy and dysfunction.

Angiotensin receptor blockade recovers hepatic UCP2 expression and aconitase and SDH activities and ameliorates hepatic oxidative damage in insulin resistant rats

Metabolic syndrome (MetS) is commonly associated with elevated renin-angiotensin system, oxidative stress, and steatohepatitis with down-regulation of uncoupling proteins (UCPs). However, the mechanisms linking renin-angiotensin system, steatosis, and UCP2 to hepatic oxidative damage during insulin resistance are not described. To test the hypothesis that angiotensin receptor activation contributes to decreased hepatic UCP2 expression and aconitase activity and to increased oxidative damage after increased glucose intake in a model of MetS, lean and obese Long Evans rats (n = 10/group) were randomly assigned to the following groups: 1) untreated Long Evans Tokushima Otsuka (lean, strain control), 2) untreated Otsuka Long Evans Tokushima Fatty (OLETF) (MetS model), 3) OLETF + angiotensin receptor blocker (ARB) (10 mg olmesartan/kg·d × 6 wk), 4) OLETF + high glucose (HG) (5% in drinking water × 6 wk), and 5) OLETF + ARB + HG (ARB/HG × 6 wk). HG increased body mass (37%), plasma triglycerides (TGs) (35%), plasma glycerol (87%), plasma free fatty acids (28%), and hepatic nitrotyrosine (74%). ARB treatment in HG decreased body mass (12%), plasma TG (15%), plasma glycerol (23%), plasma free fatty acids (14%), and hepatic TG content (42%), suggesting that angiotensin receptor type 1 (AT1) activation and increased adiposity contribute to the development of obesity-related dyslipidemia. ARB in HG also decreased hepatic nitrotyrosine and increased hepatic UCP2 expression (59%) and aconitase activity (40%), as well as antioxidant enzyme activities (50-120%), suggesting that AT1 activation also contributes to protein oxidation, impaired lipid metabolism, and antioxidant metabolism in the liver. Thus, in addition to promoting obesity-related hypertension, AT1 activation may also impair lipid metabolism and antioxidant capacity, resulting in steatosis via decreased UCP2 and tricarboxylic acid cycle activity.

The effects of angiotensin peptides and angiotensin receptor antagonists on the cell growth and angiogenic activity of GH3 lactosomatotroph cells in vitro

The local renin-angiotensin system (RAS) is present in the pituitary gland, and inhibitory effects of angiotensins on the lactosomatotroph (GH3) cell growth have been revealed. The aim of this study was to examine the influence of various angiotensin peptides and angiotensin AT1, AT2, and AT4 receptors antagonists on the cell proliferation, viability, and VEGF secretion in pituitary lactosomatotroph GH3 cell culture in order to identify receptors involved in antiproliferative effects of angiotensins on GH3 tumor cells. Cell viability and proliferation using Mosmann method and BrdU incorporation during DNA synthesis, and VEGF secretion using ELISA assay were estimated. The inhibitory effects of ang II, ang IV, and ang 5-8 on the cell viability and BrdU incorporation in GH3 culture were not abolished by AT1, AT2, and AT4 receptors antagonists. Ang II, as well as ang III and ang IV at lower concentrations stimulated the secretion of VEGF in GH3 cell culture. The secretion of VEGF was inhibited by ang III and ang IV at higher concentrations. AT1 and AT2 receptors antagonists prevented the proangiogenic effects of ang II. Ang II, ang IV, and ang 5-8 decrease the cell number and proliferation in GH3 cell culture independently of the AT1, AT2, and AT4 receptors. These peptides affect also secretion of VEGF in culture examined. Both the AT1 and AT2 receptors appear to mediate the proangiogenic effects of ang II.

Synthesis and biological evaluation of 4'-[(benzimidazole-1-yl)methyl]biphenyl-2-sulfonamide derivatives as dual angiotensin II/endothelin A receptor antagonists

A series of 4'-[(benzimidazole-1-yl)methyl]biphenyl-2-sulfonamide derivatives (Ia-Il) were synthesized and biologically evaluated. It was found that Ig, the most active compound, antagonized both Ang II AT(1) and endothelin ET(A) receptors (AT(1) IC(50)=8.5, ET(A) IC(50)=8.9 nM), and was more potent than losartan in RHRs with no significant effect on heart rate. The preliminary structure-activity relationships were also discussed in the present paper.

Calcium channel blockers, more than diuretics, enhance vascular protective effects of angiotensin receptor blockers in salt-loaded hypertensive rats

The combination therapy of an angiotensin receptor blocker (ARB) with a calcium channel blocker (CCB) or with a diuretic is favorably recommended for the treatment of hypertension. However, the difference between these two combination therapies is unclear. The present work was undertaken to examine the possible difference between the two combination therapies in vascular protection. Salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP) were divided into 6 groups, and they were orally administered (1) vehicle, (2) olmesartan, an ARB, (3) azelnidipine, a CCB, (4) hydrochlorothiazide, a diuretic, (5) olmesartan combined with azelnidipine, or (6) olmesartan combined with hydrochlorothiazide. Olmesartan combined with either azelnidipine or hydrochlorothiazide ameliorated vascular endothelial dysfunction and remodeling in SHRSP more than did monotherapy with either agent. However, despite a comparable blood pressure lowering effect between the two treatments, azelnidipine enhanced the amelioration of vascular endothelial dysfunction and remodeling by olmesartan to a greater extent than did hydrochlorothiazide in salt-loaded SHRSP. The increased enhancement by azelnidipine of olmesartan-induced vascular protection than by hydrochlorothiazide was associated with a greater amelioration of vascular nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, superoxide, mitogen-activated protein kinase activation, and with a greater activation of the Akt/endothelial nitric oxide synthase (eNOS) pathway. These results provided the first evidence that a CCB potentiates the vascular protective effects of an ARB in salt-sensitive hypertension, compared with a diuretic, and provided a novel rationale explaining the benefit of the combination therapy with an ARB and a CCB.

Angiotensin II modulates VEGF-driven angiogenesis by opposing effects of type 1 and type 2 receptor stimulation in the microvascular endothelium

Vascular endothelial growth factor (VEGF) is a main stimulator of pathological vessel formation. Nevertheless, increasing evidence suggests that Angiotensin II (Ang II) can play an augmentory role in this process. We thus analyzed the contribution of the two Ang II receptor types, AT(1)R and AT(2)R, in a mouse model of VEGF-driven angiogenesis, i.e. oxygen-induced proliferative retinopathy. Application of the AT(1)R antagonist telmisartan but not the AT(2)R antagonist PD123,319 largely attenuated the pathological response. A direct effect of Ang II on endothelial cells (EC) was analyzed by assessing angiogenic responses in primary bovine retinal and immortalized rat microvascular EC. Selective stimulation of the AT(1)R by Ang II in the presence of PD123,319 revealed a pro-angiogenic activity which further increased VEGF-driven EC sprouting and migration. In contrast, selective stimulation of the AT(2)R by either CGP42112A or Ang II in the presence of telmisartan inhibited the VEGF-driven angiogenic response. Using specific inhibitors (pertussis toxin, RGS proteins, kinase inhibitors) we identified G(12/13) and G(i) dependent signaling pathways as the mediators of the AT(1)R-induced angiogenesis and the AT(2)R-induced inhibition, respectively. As AT(1)R and AT(2)R stimulation displays opposing effects on the activity of the monomeric GTPase RhoA and pro-angiogenic responses to Ang II and VEGF requires activation of Rho-dependent kinase (ROCK), we conclude that the opposing effects of the Ang II receptors on VEGF-driven angiogenesis converge on the regulation of activity of RhoA-ROCK-dependent EC migration.

Fimasartan

Fimasartan (BR-A-657; BR-A-657-K; Kanarb®), an angiotensin II receptor antagonist with selectivity for the AT(1) receptor subtype, is being developed by Boryung Pharmaceutical as an oral treatment for hypertension. Fimasartan has been approved for use in patients with hypertension in South Korea and has been evaluated in three phase III clinical trials (i.e. NCT00922480, NCT01135212, and NCT01258673). This review discusses the development history and scientific profile of this new compound. This summary has been extracted from Wolters Kluwer's Adis R&D Insight drug pipeline database. Adis R&D Insight tracks and evaluates drug development worldwide through the entire development process, from discovery, through pre-clinical and clinical studies to market launch.

Evidence for a dose effect of renin-angiotensin system inhibition on progression of microalbuminuria in Type 2 diabetes: a meta-analysis

AIMS

Renin-angiotensin inhibitors in Type 2 diabetes and microalbuminuria reduce renal and cardiovascular risk, but evidence supporting use of maximal tolerated dose is unclear. We aimed to determine the extent of renin-angiotensin inhibitor dose-dependent effects from randomized trials carried out in a clinical setting.

METHODS

In a meta-analysis of randomized clinical trials, alternate doses of angiotensin receptor blockers or angiotensin converting enzyme inhibitors in patients with Type 2 diabetes and microalbuminuria were compared. MEDLINE, EMBASE and the Cochrane Register of Controlled Trials were searched from January 2006 to August 2010. Trials prior to January 2006 were identified from a prior systematic review. Identified outcomes were albumin excretion rate, progression and regression of albuminuria and adverse events.

RESULTS

Four trials including 1051 patients compared doses of angiotensin receptor blockers. No trials compared doses of angiotensin converting enzyme inhibitor. The percentage decline in albumin excretion rate from baseline was greater with higher doses (18% higher, 95% CI 8-28%), the regression to normoalbuminuria was greater (OR 1.66, 95% CI 1.22-2.27), with less progression to macroalbuminuria (OR 0.62, CI 0.38-1.02). Adverse events were fewer with lower-dose angiotensin receptor blockers (OR 1.32, 95% CI 0.90-1.92).

CONCLUSIONS

Higher-dose compared with lower-dose angiotensin receptor blockers in Type 2 diabetes with microalbuminuria are associated with significantly reduced albumin excretion rate and increased regression to normoalbuminuria. Adverse events are more frequent, but not significantly so. There is potential for trials to determine clinical cardiovascular and renal outcomes at differing doses. Our findings support current recommendations to titrate renin-angiotensin inhibitors to maximum dose whilst considering risk of adverse side effects with higher doses.

Vascular protection by angiotensin receptor antagonism involves differential VEGF expression in both hemispheres after experimental stroke

We identified that the angiotensin receptor antagonist, candesartan, has profound neurovascular protective properties when administered after ischemic stroke and was associated with a proangiogenic state at least partly explained by vascular endothelial growth factor A (VEGFA). However, the spatial distribution of vascular endothelial growth factor (VEGF) isoforms and their receptors remained unknown. Protein analysis identified a significant increase in vascular endothelial grow factor B (VEGFB) in the cerebrospinal fluid (CSF) and the ischemic hemispheres (with increased VEGF receptor 1 activation) of treated animals (p<0.05) which was co-occurring with an increase in protein kinase B (Akt) phosphorylation (p<0.05). An increase in VEGFA protein in the contralesional hemisphere corresponded to a significant increase in vascular density at seven days (p<0.01) after stroke onset. Vascular restoration by candesartan after stroke maybe related to differential regional upregulation of VEGFB and VEGFA, promoting a “prosurvival state” in the ischemic hemisphere and angiogenesis in the contralesional side, respectively. These vascular changes in both hemispheres after effective treatment are likely to contribute to enhanced recovery after stroke.

New approaches to the treatment of diabetic retinopathy

Diabetic retinopathy (DR) is a leading cause of visual impairment in working age in industrialized countries. It is classified as non-proliferative (mild, moderate or severe) and proliferative, with diabetic macular oedema potentially developing at any of these stages. The prevalence and incidence of DR increase with diabetes duration and worsening of metabolic and blood pressure control. Current approaches to prevent and/or treat DR include optimized control of blood glucose and blood pressure and screening for early identification of high-risk, although still asymptomatic, retinal lesions. Results from recent clinical trials suggest a role for blockers of the renin-angiotensin system (angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers) and for fenofibrate in reducing progression and/or inducing regression of mild-to-moderate non-proliferative DR. Intravitreal administration of anti-vascular endothelial growth factor (VEGF) agents was shown to reduce visual loss in more advanced stages of DR, especially in macular oedema.

Higher serum potassium level associated with late stage chronic kidney disease

BACKGROUND

The serum potassium (K+) level is kept in a narrow range to sustain normal physiology within the human body by the kidneys. The serum K+ level in different stages of chronic kidney disease (CKD) remains undefined.

METHODS

We conducted a cross-sectional study to observe the serum K+ level in patients without clinical manifestations of hyperkalemia in the late stages of CKD (stages 3-5). A total of 531 patients with late stage CKD were included and followed up for at least 1 year, from March 2006 to May 2007. The patients were sub-grouped by stages of CKD, which were determined by a "Modification of Diet in Renal Disease" equation estimating the glomerular filtration rate (eGFR). The serum creatinine, eGFR and K+ levels were recorded at least twice during the study. We analyzed the average K+ level in these late-stage CKD patients.

RESULTS

The average K+ level increased along with renal function deterioration in the late stages of CKD (stage 3: 4.36 ± 0.49; stage 4: 4.50 ± 0.55; stage 5: 4.69 ± 0.73 mEq/L, p < 0.05). Men and patients with diabetes mellitus, a low eGFR, and a low hemoglobin might have higher levels of serum K+. We also noticed that there was a linear increase in the standard deviation of the serum K+ level as renal function deteriorated. The use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers was not associated with hyperkalemia in our patients.

CONCLUSION

Our results reflected that the serum K+ level increased in correlation with the decline in the eGFR in the late stages of CKD. Also, male gender, diabetes mellitus, and anemia might be risk factors for higher K+ levels in CKD patients. The variation in the serum K+ level became wider as renal failure progressed.

The evolution of angiotensin blockade in the management of cardiovascular disease

Dysregulation of the renin-angiotensin system is implicated in many cardiovascular and renal pathologies. Discovery of the renin-angiotensin system represents a major advance in the understanding of hypertension and cardiovascular disease, leading to the development of the anti-angiotensin medications: angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and direct renin inhibitors. Clinical trials have shown that drugs in each of these classes have a protective effect on vascular organs that surpass the protection associated with the lowering of blood pressure alone.

Differential effects of enalapril and losartan on body composition and indices of muscle quality in aged male Fischer 344 × Brown Norway rats

The primary purpose of the present set of studies was to provide a direct comparison of the effects of the angiotensin-converting enzyme inhibitor enalapril and the angiotensin receptor blocker losartan on body composition, physical performance, and muscle quality when administered late in life to aged rats. Overall, enalapril treatment consistently attenuated age-related increases in adiposity relative to both placebo and losartan. The maximal effect was achieved after 3 months of treatment (between 24 and 27 months of age), at a dose of 40 mg/kg and was observed in the absence of any changes in physical activity, body temperature, or food intake. In addition, the reduction in fat mass was not due to changes in pathology given that enalapril attenuated age-related increases in tumor development relative to placebo- and losartan-treated animals. Both enalapril and losartan attenuated age-related decreases in grip strength, suggesting that changes in body composition appear dissociated from improvements in physical function and may reflect a differential impact of enalapril and losartan on muscle quality. To link changes in adiposity to improvements in skeletal muscle quality, we performed gene array analyses to generate hypotheses regarding cell signaling pathways altered with enalapril treatment. Based on these results, our primary follow-up pathway was mitochondria-mediated apoptosis of myocytes. Relative to losartan- and placebo-treated rats, only enalapril decreased DNA fragmentation and caspase-dependent apoptotic signaling. These data suggest that attenuation of the severity of skeletal muscle apoptosis promoted by enalapril may represent a distinct mechanism through which this compound improves muscle strength/quality.

Azilsartan medoxomil (Edarbi) the eighth ARB

The angiotensin receptor blocker (ARB) azilsartan medoxomil (Edarbi-Takeda) was recently approved by the FDA for oral treatment of hypertension, either alone or combined with other drugs. It is the eighth ARB approved for this indication.

[Effects of drugs for lifestyle-related diseases on bone metabolism]

Accumulating evidence indicates several drugs for lifestyle-related diseases are involved in bone metabolism. Drugs that might reduce fracture incidence are statins, β-blockers and thiazide diuretics, and those that might increase fractures are thiazolidinediones and loop diuretics. It is yet controversial whether ACE inhibitors, angiotensin receptor- II blockers and aldosterone receptor antagonists are indeed involved in the increase or the decrease in fracture incidence.

Acute angiotensin II receptor blockade improves insulin-induced microvascular function in hypertensive individuals

OBJECTIVE

An effect of insulin that is crucial for stimulating glucose uptake is its ability to increase the number of perfused capillaries, and thereby enhance its own delivery, and that of glucose, to muscle cells. To unravel possible mechanisms involved in the insulin-sensitizing effects of angiotensin II receptor blockers (ARBs) in hypertensive individuals we investigated the effect of single-dose ARB administration on insulin-mediated microvascular perfusion in hypertensive individuals.

METHODS

We examined the effects of ARB administration on hyperinsulinemia-associated capillary density by measuring baseline skin capillary density, capillary density during reactive hyperemia (hyperemic capillary recruitment), and capillary density during venous congestion in 17 hypertensive individuals in the basal state, during a hyperinsulinemic euglycemic clamp, and during a hyperinsulinemic clamp with acute ARB administration (600 mg irbesartan), acute calcium channel blockade (CCB; 10mg felodipine ER), as a control for the reduction in blood pressure, or placebo. In addition, insulin sensitivity and blood pressure were measured.

RESULTS

Compared to the basal state, hyperinsulinemia increased baseline capillary density (57.3 ± 6.8 vs. 60.3 ± 7.9 n/mm(2), P<0.01), but not hyperemic capillary recruitment. ARB and CCB treatment induced similar blood pressure reductions. Compared to placebo, ARB, but not CCB, increased hyperinsulinemia-associated baseline capillary density (+2.3 ± 3.4 (P=0.02) and -0.4 ± 4.4n/mm(2), respectively). Hyperinsulinemia-associated hyperemic capillary recruitment was not altered by either treatment. Compared to placebo, neither ARB nor CCB treatment enhanced insulin sensitivity.

CONCLUSIONS

Acute ARB administration increases insulin-induced microvascular perfusion in mildly hypertensive individuals; this beneficial effect on microvascular perfusion was however not associated with increased insulin-mediated glucose uptake.

Is vascular stiffness a target for therapy?

BACKGROUND

Early cardiovascular disease starts in the endothelium leading to functional changes in the vasculature. These changes can be depicted by assessment of arterial stiffness or elasticity. There are several techniques to assess arterial stiffness. Increased arterial stiffness or decreased arterial elasticity has been associated with cardiovascular risk factors. There is now evidence that small artery elasticity is a strong predictor for arterial hypertension. Moreover arterial elasticity provides extra prognostic information beyond arterial blood pressure measurement. Arterial stiffness attenuation may reflect the true reduction of arterial wall damage.

RESULTS

ACE-inhibitors, angiotensin II receptor blockers, aldosterone antagonists and calcium antagonists have favorable effects in improving arterial elasticity, while beta-blockers have an inverse effect. Diuretics have not been evaluated. Lipid lowering therapy, some antidiabetic therapy have shown to reduce arterial stiffness. Inflammatory and infectious diseases have been associated with vascular inflammation and consequently increase in arterial stiffness. The effect of anti-inflammatory agents and antiretroviral therapy on arterial stiffness is under investigation.

CONCLUSIONS

Measurement of arterial stiffness will not only be helpful in the detection of early vascular disease but also as a tool in the selection and follow-up monitoring of therapeutic strategies aimed at preventing or delaying progression of vascular disease.

The comparative effects of azilsartan medoxomil and olmesartan on ambulatory and clinic blood pressure

The current study assesses the antihypertensive efficacy and safety of the investigational angiotensin receptor blocker (ARB), azilsartan medoxomil (AZL-M), compared with placebo and the ARB olmesartan medoxomil (OLM-M). This randomized, double-blind, placebo-controlled, multicenter study assessed change from baseline in mean 24-hour ambulatory systolic blood pressure (SBP) following 6 weeks of treatment. Patients with primary hypertension (n=1275) and baseline 24-hour mean ambulatory systolic pressure ≥ 130 mm Hg and ≤ 170 mm Hg were studied; 142 received placebo and the remainder received 20 mg, 40 mg, or 80 mg AZL-M or 40 mg OLM-M. Mean age of participants was 58 ± 11 years, baseline mean 24-hour SBP was 146 mm Hg. Dose-dependent reductions in 24-hour mean SBP at study end occurred in all AZL-M groups. Reduction in 24-hour mean SBP was greater with AZL-M 80 mg than OLM-M 40 mg by 2.1 mm Hg (95% confidence interval, -4.0 to -0.1; P=.038), while AZL-M 40 mg was noninferior to OLM-M 40 mg. The side effect profiles of both ARBs were similar to placebo. AZL-M is well tolerated and more efficacious at its maximal dose than the highest dose of OLM-M.

Barriers to blood pressure control: a STITCH substudy

Despite improvements in blood pressure (BP) control, a substantial percentage of patients do not achieve target. The relative importance of determinants of poor BP control is unclear. Therefore, the authors conducted a post hoc exploratory analysis to assess determinants of BP control. Data were collected in 45 general practices, which enrolled patients with uncontrolled hypertension. Antihypertensive medication changes throughout the 6-month follow-up period were documented. Baseline and 6-month BPs were recorded. Of the 2030 patients analyzed, 320 had diabetes. Overall, 42% of patients did not achieve BP control. In multivariate analysis, failure to intensify therapy was identified as a significant independent predictor of lesser BP reduction. Of patients unable to reach target after 6 months, only 25% were prescribed ≥ 3 drugs. Patients with diabetes were significantly less likely to reach target than those without (26% vs 64%, P<.001). Antihypertensive therapy prescribed to patients with diabetes was only marginally more intensive than to those without. In patients with hypertension, whether with or without coexisting diabetes, poor BP control appears to be at least partially due to failure to uptitrate antihypertensive therapy. Clinical inertia is likely an important barrier to BP control.

Endogenous angiotensin II suppresses stretch-induced ANP secretion via AT1 receptor pathway

Angiotensin II (Ang II) is released by stretch of cardiac myocytes and has paracrine and autocrine effects on cardiac myocytes and fibroblasts. However, the direct effect of Ang II on the secretion of atrial natriuretic peptide (ANP) is unclear. The aim of the present study is to test whether Ang II affects stretch-induced ANP secretion. The isolated perfused beating atria were used from control and two-kidney one-clip hypertensive (2K1C) rats. The volume load was achieved by elevating the height of outflow catheter connected with isolated atria from 5cmH(2)O to 7.5cmH(2)O. Atrial stretch by volume load caused increases in atrial contractility by 60% and in ANP secretion by 100%. Ang II suppressed stretch-induced ANP secretion and tended to increase atrial contractility whereas losartan stimulated stretch-induced ANP secretion. Neither PD123319 nor A779 had direct effect on stretch-induced ANP secretion. The suppressive effect of Ang II on stretch-induced ANP secretion was blocked by the pretreatment of losartan but not by the pretreatment of PD123319 or A779. In hypertrophied atria from 2K1C rats, stretch-induced ANP concentration attenuated and atrial contractility augmented. The response of stretch-induced ANP secretion to Ang II and losartan augmented. The expression of AT1 receptor protein and mRNA increased but AT2 and Mas receptor mRNA did not change in 2K1C rat atria. Therefore, we suggest that Ang II generated endogenously by atrial stretch suppresses stretch-induced ANP secretion through the AT1 receptor and alteration of Ang II effect in 2K1C rat may be due to upregulation of AT1 receptor.

[The effect of ARB on prevention of atherosclerosis]

Atherosclerosis is an inflammatory disease of vascular wall initiated and amplified by oxidative stress. Evidence has accumulated over the past decade that angiotensin II (Ang II) induces oxidative stress in hypertension which is one of the major risk factors of atherosclerosis. Angiotensin receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs) can reduce oxidative stress and inflammation in hypertensive patients. As a result, ACEIs reduce major cardiovascular events including myocardial infarction, stroke, and heart failure, whereas it has not been elucidated whether ARBs might be more effective at reducing atherosclerosis than ACEIs or not. The recent meta-analysis have been leading to the answer that ARBs should be considered as baseline therapy in hypertension.

[Pharmacological prevention of cardiovascular diseases]

At present, cardiology makes use of a wide range of drugs belonging to various pharmacological classes for both preventing and treating cardiovascular diseases. Results of recent large clinical trials show the importance of carrying out preventive actions, but data of evidence based medicine suggest that only some of the methods of pharmacological prophylaxis have unequivocally demonstrated their ability to improve the forecast of life for patients with cardiovascular pathology. We have summarized data on the efficacy of some groups of drugs used in cardiology and assessed this information from the positions of proved validity of the prophylactic effect in particular groups of patients.

Cardio classics revisited &ndash; focus on the role of candesartan

Angiotensin II receptor blockers (ARBs) are antihypertensive agents with considerable evidence of efficacy and safety for the reduction of cardiovascular (CV) disease risk in numerous patient populations across the CV continuum. There are several agents within this class, all of which have contributed to various degrees, to this evidence base. The evidence with ARBs continues to accumulate, with ongoing trials investigating their role in additional patient populations, potentially expanding their efficacy across a broad spectrum of CV disease states. Cardiovascular disease (CVD) is a leading cause of death around the world, accounting for approximately 29.2% of total global deaths. Of all the deaths attributed to CVD, approximately 43% are due to ischemic heart disease, 33% to cerebrovascular disease, and 23% to hypertensive and other heart conditions. CVD has been represented as a "CV continuum". This continuum concept can be used to describe CVD in general or in specific vascular beds (eg, coronary artery disease or cerebrovascular disease). This review article will discuss the results of the landmark ARB candesartan clinical trials published over the past decade. The evidence presented spans the entire CV continuum, including the effects of ARBs in at-risk patients, stroke, myocardial infarction (MI), and heart failure (HF), as well as a brief discussion of ongoing trials.

Serum fibroblast growth factor-21 concentration is associated with residual renal function and insulin resistance in end-stage renal disease patients receiving long-term peritoneal dialysis

Fibroblast growth factor-21 (FGF-21) is a new metabolic regulator, which is related to antiobesity and insulin sensitivity in vivo. However, the clinical implication of FGF-21 is poorly understood. To investigate whether FGF-21 may play a role as a metabolic regulator in patients with end-stage renal disease, we measured serum concentrations of FGF-21, inflammatory markers, and metabolic parameters in healthy people (n = 63) and nondiabetic patients receiving peritoneal dialysis (PD, n = 72). The patients were treated with angiotensin receptor blocker for 6 months, and the changes in FGF-21 concentration and metabolic parameters were assessed. Compared with controls, serum FGF-21 concentration was 8 times higher in patients undergoing PD (754.2 ± 463.5 vs 86.9 ± 60.2 pg/mL, P < .001). In controls, only lipid parameters correlated positively with FGF-21 concentration. In contrast, inflammatory markers (interleukin-6, fibrinogen, high-sensitivity C-reactive protein) and homeostasis model assessment of insulin resistance (HOMA-IR) correlated positively and residual renal function correlated inversely with serum FGF-21 concentration in PD patients. In a multivariate analysis adjusting these factors, residual renal function, HOMA-IR, and fibrinogen concentration were independent determinants of serum FGF-21 concentration. After 6-month angiotensin receptor blocker treatment, serum FGF-21 concentration declined significantly by 13% and HOMA-IR and inflammatory markers improved in PD patients. These findings suggest that FGF-21 may play a role in insulin resistance in patients with end-stage renal disease.

Renin-angiotensin system blockers and modulation of radiation-induced brain injury

Radiation-induced brain injury remains a major cause of morbidity in cancer patients with primary or metastatic brain tumors. Approximately 200,000 individuals/year are treated with fractionated partial or whole-brain irradiation, and > half will survive long enough (≤6 months) to develop radiation-induced brain injury, including cognitive impairment. Although short-term treatments have shown efficacy, no long-term treatments or preventive approaches are presently available for modulating radiation-induced brain injury. Based on previous preclinical studies clearly demonstrating that renin-angiotensin system (RAS) blockers can modulate radiation-induced late effects in the kidney and lung, we and others hypothesized that RAS blockade would similarly modulate radiation-induced brain injury. Indeed, studies in the last 5 years have shown that both angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor antagonists (AT(1)RAs) can prevent/ameliorate radiation-induced brain injury, including cognitive impairment, in the rat. The mechanistic basis for this RAS blocker-mediated effect remains the subject of ongoing investigations. Putative mechanisms include, i] blockade of Ang II/NADPH oxidase-mediated oxidative stress and neuroinflammation, and ii] a change in the balance of angiotensin (Ang) peptides from the pro-inflammatory and pro-oxidative Ang II to the anti-inflammatory and anti-oxidative Ang-1-7). However, given that both ACEIs and AT(1)RAs are 1] well-tolerated drugs routinely prescribed for hypertension, 2] exhibit some antitumor properties, and 3] can prevent/ameliorate radiation-induced brain injury, they appear to be ideal drugs for future clinical trials, offering the promise of improving the quality of life of brain tumor patients receiving brain irradiation.

Metabolic regulation of coronary vascular tone: role of hydrogen peroxide, purinergic components, and angiotensin

Metabolic regulation plays an important role in modifying coronary vascular tone. We hypothesized that hydrogen peroxide, purinergic components, and angiotensin, produced by cardiac myocytes control coronary vascular tone in proportion to metabolism. We measured changes in the diameter of isolated, pressurized coronary arterioles in response to supernatant from isolated cardiac myocytes in rats (stimulated for 20-, 60-, and 120-min at 400 bpm). Changes in the diameter of arterioles were determined under control conditions following treatment of arterioles with an adenosine receptor antagonist, 8-PSPT, a P2Y1 receptor antagonist, MRS-2179, or an angiotensin II receptor antagonist, olmesartan. A supernatant (500 microl to a 2 ml bath) from myocytes stimulated for 20-, 60- and 120-min caused graded vasodilation (14.1+/-0.4, 20.2+/-1.6, 53.8+/-6.2%, P<0.01 vs. non-stimulated, respectively). In 20-min stimulation, catalase with myocyte supernatants eliminated vasodilation. Following 60-min stimulation, catalase converted myocyte supernatant-induced vasodilation to a vasoconstriction (-15.1+/-1.0%), and this vasoconstriction was eliminated by olmesartan. Upon 120-min stimulation, catalase partially reduced the vasodilation by myocyte supernatants (37.2+/-3.8%). The remaining vasodilation was converted to a vasoconstriction with 8-PSPT and MRS-2179, and this vasoconstriction was completely eliminated with olmesartan. Cardiac myocytes modulate vascular tone through the net effects of hydrogen peroxide, purinergic components (adenosine and ADP), and angiotensin in proportion to ischemia.

Smoking is associated with a high prevalence of microalbuminuria in hypertensive high-risk patients: data from I-SEARCH

BACKGROUND

Microalbuminuria (MAU) is a marker of endothelial dysfunction and a predictor of cardiovascular events. The effects of cigarette smoking on the prevalence of MAU in a high-risk population with arterial hypertension are unclear.

METHODS

The International Survey Evaluating Microalbuminuria Routinely by Cardiologists in patients with Hypertension (I-SEARCH) documented the clinical profile of 20,364 patients with arterial hypertension and cardiovascular risk factors. In this population, 13,690 patients had no history of smoking, 4,057 patients were former smokers and 2,617 patients were current smokers.

RESULTS

The prevalence of MAU was associated with the smoking status. Consumption of 1-20 cigarettes per day leads to an increase of 6.8% in the prevalence of MAU compared to non-smokers (P < 0.001). Smoking of >20 cigarettes per day was associated with a 12.5% higher prevalence of MAU compared to non-smokers, while former smokers had a 4.7% higher prevalence of MAU. Multivariable analysis revealed that smoking was independently associated with MAU [odds ratio (OR) smoking vs. non-smoking 1.16; 95% confidence interval (CI) 1.01-1.33; P < 0.05]. Particularly, a consumption of >20 cigarettes per day was associated with high odds for MAU (OR 1.33; CI 1.01-1.75; P < 0.05). Interestingly, independently of blood pressure, the use of an angiotensin receptor blocker and an ACE was associated with significantly reduced odds ratio for MAU in the smoking group, while there was no significant association in the non-smoking group.

CONCLUSION

The prevalence of MAU in hypertensive patients is higher in smokers than in non-smokers with a strong dose dependency.

Diabetic nephropathy

INTRODUCTION

Up to a third of people with type 1 or 2 diabetes will develop microalbuminuria or macroalbuminuria after 20 years.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments in people with type 1 diabetes and early nephropathy? What are the effects of treatments in people with type 1 diabetes and late nephropathy? What are the effects of treatments in people with type 2 diabetes and early nephropathy? What are the effects of treatments in people with type 2 diabetes and late nephropathy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2008 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 15 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor antagonists, captopril, glycaemic control, protein restriction, and tight control of blood pressure.

[Alteration of signal transduction-associated gene expression in rat cardiac fibroblasts induced by blocking angiotensin II receptors]

To investigate the molecular mechanism of angiotensin II (Ang II) receptor activation in adult rat cardiac fibroblasts, the expressions of cell signal transduction-associated genes were studied by using cDNA microarray. Cardiac fibroblasts of adult Sprague-Dawley rats (230~250 g) were isolated and cultured. The cells were divided into 4 groups: Ang II, Ang II + losartan, Ang II + PD123319, Ang II + losartan + PD123319. The expressions of Ang II receptors were studied by immunohistochemical staining. Total RNA was extracted and purified. After cDNA synthesis and biotin-16-dUTP labeling, the probes were denatured and hybridized with GEArray Q Series mouse G Protein-coupled Receptors Signaling Pathway Finder Gene Array (MM-025) containing 96 genes associated with 11 pathways. The arrays were scanned with a Uniscand1000 scanner and further analyzed with GEArray Analyzer software. RT-PCR was used to further confirm the results of gene microarray. The results of immunohistochemical staining showed that the expression of Ang II type 2 (AT2) receptor was evidently induced by Ang II stimulation when Ang II type 1 (AT1) receptor was blocked. The results of gene array indicated that blocking AT1 receptor changed 34 genes (more than 2 folds), 30 were down-regulated and 4 were up-regulated. The maximum change was not beyond 20 folds. The following 9 pathways were activated: cAMP/PKA, Ca2+, PKC, PLC, MAPK, PI-3 kinase, NO-cGMP, Rho, NF-kappaB pathways. Blockade of AT2 receptor caused 64 genes changing more than 2 folds (48 were down-regulated and 16 were up-regulated). Eleven pathways were basically activated. The change of the following 7 genes was over 30 folds: Cyp19a1 (37 folds), Il1r2 (42 folds), Cflar (53 folds), Bcl21 (31 folds), Pik3cg (278 folds), Cdkn1a (90 folds), Agt (162 folds). According to the activated extent, the signal transduction pathways in turn were PI-3 kinase, NF-kappaB and JAK-STAT pathways. Blocking both AT1 and AT2 receptors changed 46 genes more than 2 folds (36 were down-regulated and 10 were up-regulated). Eleven pathways were basically activated. The results of RT-PCR of IL-1beta and TNF-alpha confirmed the observations in gene microarray. Our results show that Ang II can induce a high expression of AT2 receptor in adult rat cardiac fibroblasts when AT1 receptor is blocked, and the signal mechanism of AT2 receptor is clearly different from that of AT1 receptor.

[Effect of irbesartan on focal cerebral ischemia in rats]

AIM

To investigate whether the selective AT1 receptor antagonist irbesartan exerts neuroprotective effect on focal cerebral ischemia in normotensive rats.

METHODS

Cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 90 min followed by reperfusion, with the monitoring of laser Doppler flowmetry. To avoid the interaction with peripheral AT1 receptors, irbesartan was infused intracerebroventricularly (ICV) at a dose which effectively inhibited brain- but not vascular AT1 receptors. Neurological status was evaluated daily after MCAO. Rats were killed and brain samples were collected for the measurement of infarct size and immunohistochemical evaluation of apoptosis by deoxynucleotidyltransferase-mediated biotinylated UTP nick end labeling (TUNEL) and expression of activated Caspase-3 and the cleavage fragment of poly (ADP-ribose) polymerase (PARP).

RESULTS

Treatment with irbesartan improved significantly the neurobehavioral functions after cerebral ischemia. The infarct size was reduced about 42% on day 7 after MCAO (P < 0.05). Meanwhile,irbesartan treatment significantly decreased the number of TUNEL-positive cells in the penumbra. The expression of activated Caspase-3 and the downstream cleavage fragment of poly (ADP-ribose) polymerase in the penumbra were also inhibited by irbesartan therapy on day 3 after transient cerebral ischemia.

CONCLUSION

Angiotensin AT1 receptor antagonist exhibits neuroprotection against transient cerebral ischemia in the brain. The neuroprotective effects in ischemic tissue may be associated with its inhibition of apoptotic cell death in the penumbra.

[Regulation of the transcription of oxidized low-density-lipoprotein receptor by angiotensin II]

AIM

To observe the effects of different concentrations Angiotensin II on the transcription of LOX1 in culture human umbilical vein endothelial cells and to explore its mechanism.

METHODS

Reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

(1) Angiotensin II cause a concentration-dependent increase of the level of LOX1 mRNA. (2) Losartan, the inhibitor of AT1 receptor subtypes, inhibited this effects.

CONCLUSION

Angiotensin II stimulated the gene expression of LOX1 by activating AT1 receptor subtype in culture human endothelial cells.