Differential renal effects of candesartan at high-and ultra-high doses in diabetic mice: potential role of ACE2/AT2R/Mas

High doses of Ang II receptor (AT1R) blockers (ARBs) are renoprotective in diabetes. Underlying mechanisms remain unclear. We evaluated whether high/ultra-high doses of candesartan (ARB) up-regulate angiotensin-converting enzyme 2 (ACE2)/Ang II type 2 receptor (AT2R)/Mas receptor [protective axis of the of the renin–angiotensin system (RAS)] in diabetic mice. Systolic blood pressure (SBP), albuminuria and expression/activity of RAS components were assessed in diabetic db/db and control db/+ mice treated with increasing candesartan doses (intermediate, 1 mg/kg/d; high, 5 mg/kg/d; ultra-high, 25 and 75 mg/kg/d; 4 weeks). Lower doses candesartan did not influence SBP, but ultra-high doses reduced SBP in both groups. Plasma glucose and albuminuria were increased in db/db compared with db/+ mice. In diabetic mice treated with intermediate dose candesartan, renal tubular damage and albuminuria were ameliorated and expression of ACE2, AT2R and Mas and activity of ACE2 were increased, effects associated with reduced ERK1/2 phosphorylation, decreased fibrosis and renal protection. Ultra-high doses did not influence the ACE2/AT2R/Mas axis and promoted renal injury with increased renal ERK1/2 activation and exaggerated fibronectin expression in db/db mice. Our study demonstrates dose-related effects of candesartan in diabetic nephropathy: intermediate–high dose candesartan is renoprotective, whereas ultra-high dose candesartan induces renal damage. Molecular processes associated with these effects involve differential modulation of the ACE2/AT2R/Mas axis: intermediate–high dose candesartan up-regulating RAS protective components and attenuating pro-fibrotic processes, and ultra-high doses having opposite effects. These findings suggest novel mechanisms through the protective RAS axis, whereby candesartan may ameliorate diabetic nephropathy. Our findings also highlight potential injurious renal effects of ultra-high dose candesartan in diabetes

Impaired endothelial function of the retinal vasculature in hypertensive patients

<p><b>Background and Purpose:</b> Arterial hypertension constitutes a central factor in the pathogenesis of stroke. We examined endothelial function of the retinal vasculature as a model of the cerebral circulation.</p> <p><b>Methods:</b> Thirty-eight young subjects (19 hypertensive and 19 normotensive) were treated with the AT1-receptor blocker candesartan cilexetil and placebo, each over 7 days. Retinal capillary flow and blood flow velocity in the central retinal artery were assessed with scanning laser Doppler flowmetry and pulsed Doppler ultrasound, respectively. NG-monomethyl-L-arginine (L-NMMA) was infused to inhibit nitric oxide (NO) synthesis. Diffuse luminance flicker was applied to stimulate NO release.</p> <p><b>Results:</b> In normotensive subjects, L-NMMA decreased retinal capillary flow by 8.2%±13% (P<0.05) and flickering light increased mean blood flow velocity in the central retinal artery by 19%±29% (P<0.01). In contrast, no significant change to these provocative tests was seen in hypertensive subjects. Treatment with candesartan cilexetil restored a normal pattern of reactivity in retinal capillaries (L-NMMA: decrease in perfusion by 10%±17%, P<0.05) and the central retinal artery (flicker: increase in mean blood flow velocity by 42%±31%, P<0.001) in hypertensive patients.</p> <p><b>Conclusions:</b> Endothelial function of the retinal vasculature is impaired in early essential hypertension but can be improved by AT1-receptor blockade.</p&gt

Worsening renal function and outcome in heart failure patients with reduced and preserved ejection fraction and the impact of angiotensin receptor blocker treatment: data from the CHARM-study programme

Aims We investigated the association between worsening renal function (WRF) that occurs during renin–angiotensin–aldosterone system inhibition initation and outcome in heart failure (HF) patients with preserved ejection fraction (HFPEF) and compared this with HF patients with reduced ejection fraction (HFREF). Methods and results We examined changes in estimated glomerular filtration rate (GFR) and the relationship between WRF (defined as ≥26.5 µmol/L and ≥25% increase in serum creatinine from baseline to 6 weeks) and outcome, according to randomized treatment, in patients with HFREF (EF <45%; n = 1569) and HFPEF (EF ≥45%; n = 836) in the CHARM programme. The primary outcome was cardiovascular death or HF hospitalization. Estimated GFR decreased 9.0 ± 21 vs. 4.0 ± 21 mL/min/1.73 m2 with candesartan and placebo, respectively, and this was similar in HFREF and HFPEF. WRF developed more frequently with candesartan, 16% vs. 7%, P < 0.001, with similar findings in patients with HFREF and HFPEF. WRF was associated with a higher risk of the primary outcome: multivariable hazard ratio (HR) 1.26, 95% confidence interval 1.03–1.54, P = 0.022, in both treatment groups, and in both HFREF and HFPEF (P for interaction 0.98). In HFREF, WRF was mostly related to HF hospitalization, while in HFPEF, WRF seemed more associated with mortality. Conclusions GFR decreased more and WRF was more common with candesartan compared with placebo, and this was similar in HFREF and HFPEF. WRF was associated with worse outcomes in HFREF and HFPEF. Although no formal interaction was present, the association between candesartan treatment, WRF, and type of clinical outcome was slightly different between HFREF and HFPEF

Effects of candesartan, an angiotensin II receptor type I blocker, on atrial remodeling in spontaneously hypertensive rats

Hypertension-induced structural remodeling of the left atrium (LA) has been suggested to involve the renin–angiotensin system. This study investigated whether treatment with an angiotensin receptor blocker, candesartan, regresses atrial remodeling in spontaneously hypertensive rats (SHR). Effects of treatment with candesartan were compared to treatment with a nonspecific vasodilatator, hydralazine. Thirty to 32-week-old adult male SHR were either untreated (n = 15) or received one of either candesartan cilexetil (n = 9; 3 mg/kg/day) or hydralazine (n = 10; 14 mg/kg/day) via their drinking water for 14 weeks prior to experiments. Untreated age- and sex-matched Wistar- Kyoto rats (WKY; n = 13) represented a normotensive control group. Untreated SHR were hypertensive, with left ventricular hypertrophy (LVH) compared to WKY, but there were no differences in systolic pressures in excised, perfused hearts. LA from SHR were hypertrophied and showed increased fibrosis compared to those from WKY, but there was no change in connexin-43 expression or phosphorylation. Treatment with candesartan reduced systolic tail artery pressures of conscious SHR below those of normotensive WKY and caused regression of both LVH and LA hypertrophy. Although hydralazine reduced SHR arterial pressures to those of WKY and led to regression of LA hypertrophy, it had no significant effect on LVH. Notably, LA fibrosis was unaffected by treatment with either agent. These data show that candesartan, at a dose sufficient to reduce blood pressure and LVH, did not cause regression of LA fibrosis in hypertensive rats. On the other hand, the data also suggest that normalization of arterial pressure can lead to the regression of LA hypertrophy

Urinary excretion of RAS, BMP, and WNT pathway components in diabetic kidney disease.

Abstract The renin-angiotensin system (RAS), bone morphogenetic protein (BMP), and WNT pathways are involved in pathogenesis of diabetic kidney disease (DKD). This study characterized assays for urinary angiotensinogen (AGT), gremlin-1, and matrix metalloproteinase 7 (MMP-7), components of the RAS, BMP, and WNT pathways and examined their excretion in DKD. We measured urine AGT, gremlin-1, and MMP-7 in individuals with type 1 diabetes and prevalent DKD (n = 20) or longstanding (n = 61) or new-onset (n = 10) type 1 diabetes without DKD. These urine proteins were also quantified in type 2 DKD (n = 11) before and after treatment with candesartan. The utilized immunoassays had comparable inter- and intra-assay and intraindividual variation to assays used for urine albumin. Median (IQR) urine AGT concentrations were 226.0 (82.1, 550.3) and 13.0 (7.8, 20.0) μg/g creatinine in type 1 diabetes with and without DKD, respectively (P < 0.001). Median (IQR) urine gremlin-1 concentrations were 48.6 (14.2, 254.1) and 3.6 (1.7, 5.5) μg/g, respectively (P < 0.001). Median (IQR) urine MMP-7 concentrations were 6.0 (3.8, 10.5) and 1.0 (0.4, 2.9) μg/g creatinine, respectively (P < 0.001). Treatment with candesartan was associated with a reduction in median (IQR) urine AGT/creatinine from 23.5 (1.6, 105.1) to 2.0 (1.4, 13.7) μg/g, which did not reach statistical significance. Urine gremlin-1 and MMP-7 excretion did not decrease with candesartan. In conclusion, DKD is characterized by markedly elevated urine AGT, MMP-7, and gremlin-1. AGT decreased in response to RAS inhibition, suggesting that this marker reflects therapeutic response. Urinary components of the RAS, BMP, and WNT pathways may identify risk of DKD and aid development of novel therapeutics

Contractile force is enhanced in Aortas from pendrin null mice due to stimulation of angiotensin II-dependent signaling.

Pendrin is a Cl-/HCO3- exchanger expressed in the apical regions of renal intercalated cells. Following pendrin gene ablation, blood pressure falls, in part, from reduced renal NaCl absorption. We asked if pendrin is expressed in vascular tissue and if the lower blood pressure observed in pendrin null mice is accompanied by reduced vascular reactivity. Thus, the contractile responses to KCl and phenylephrine (PE) were examined in isometrically mounted thoracic aortas from wild-type and pendrin null mice. Although pendrin expression was not detected in the aorta, pendrin gene ablation changed contractile protein abundance and increased the maximal contractile response to PE when normalized to cross sectional area (CSA). However, the contractile sensitivity to this agent was unchanged. The increase in contractile force/cross sectional area observed in pendrin null mice was due to reduced cross sectional area of the aorta and not from increased contractile force per vessel. The pendrin-dependent increase in maximal contractile response was endothelium- and nitric oxide-independent and did not occur from changes in Ca2+ sensitivity or chronic changes in catecholamine production. However, application of 100 nM angiotensin II increased force/CSA more in aortas from pendrin null than from wild type mice. Moreover, angiotensin type 1 receptor inhibitor (candesartan) treatment in vivo eliminated the pendrin-dependent changes contractile protein abundance and changes in the contractile force/cross sectional area in response to PE. In conclusion, pendrin gene ablation increases aorta contractile force per cross sectional area in response to angiotensin II and PE due to stimulation of angiotensin type 1 receptor-dependent signaling. The angiotensin type 1 receptor-dependent increase in vascular reactivity may mitigate the fall in blood pressure observed with pendrin gene ablation

POST-ISCHEMIC TREATMENT WITH CANDESARTAN PROTECTS FROM CEREBRAL ISCHEMIC REPERFUSION INJURY IN NORMOTENSIVE RAT

Large body of evidences has indicated that the renin – angiotensin system (RAS) and its effector peptide Angiotensin II may be involved in the pathophysiology of stroke. Previous studies showed that preischemic RAS inhibition reduced brain injury but effects of post-ischemic RAS inhibition on ischemic/reperfusion injuries have not completely been elucidated. Therefore, the present study has investigated the effects of post-ischemic AT1 receptor blocked with candesartan treatment on cerebral infarction and motor function following transient focal cerebral ischemia in normotensive rats. Male normotensive rats were studied in three groups as sham, ischemic control and ischemic group which received candesartan (0.3mg/kg) at the beginning of reperfusion period. Transient focal cerebral ischemia was induced by 90 min occlusion of the left middle cerebral artery, followed by 24h reperfusion. Neurological deficit score (NDS ) evaluated at the end of the reperfusion period. Total, cortical and striatal infarct volumes were determined using TTC staining technique. Animals in sham group had normal motor function and no ischemic lesions were observed in their cortical or striatal regions. MCAO in control ischemic group produced considerable infarctions in cortex and striatum in conjunction with severe impaired motor functions. AT1 receptor blocked with candesartan significantly reduced infarct volumes in the cortex and the striatum with improvement in NDS compared to control ischemic group. In conclusion, the results of the present study indicated that AT1 receptor blocked with candesartan can decrease ischemic brain injury and improve neurological outcome

Solid Dispersion System Candesartan-cilexetil Mannitol Co-Grinding Method

Research on solid dispersion systems had been done to improve physicochemical characteristics and the dissolution rate of candesartan-cilexetil a had been conducted. Candesartan cilexetil is included in BCS (Biopharmaceutical Classification System) class II, which has low solubility and high permeability which causes poor absorption of drugs in the digestive tract. Solid dispersions were prepared through the grinding method using mannitol. The formula with 3 comparisons between candesartan-cilexetil and mannitol 1:1, 1:3, and 1:5. A mixture of physics of candesartan cilexetil-mannitol was made without a solid dispersions system which was 1:1 as a comparison. Solid dispersion formed was characterized by particle size distribution analysis, Fourier transforms infrared (FT-IR), X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), determination rate, and dissolution test. The result particle size distribution analysis showed grinding method there were solid dispersions mixed perfectly. The FT-IR of this analysis showed no interaction between candesartan-cilexetil mannitol in solid dispersion powder. The result of X-ray diffraction showed a decrease in crystallization degree. The DSC result showed a shift in endothermic peak candesartan-cilexetil. The manufacture of a solid dispersion system of candesartan-cilexetil mannitol can improve the physicochemical characteristics and the dissolution rate of candesartan-cilexetil compared with physical mixtures. The result in the dissolution was solid dispersion 1 = 53.1990 %, solid dispersion 2 = 54.3621 %, and solid dispersion 3 = 62.3621 %. The statistical result of dissolution efficiency using the Kruskal-Willis test with significant = 0.009(< 0.05) showed the difference among the dissolution efficiency of candesartan-cilexetil, physical mixture, and each solid dispersion

Prevalence of prediabetes and undiagnosed diabetes in patients with HFpEF and HFrEF and associated clinical outcomes

Purpose: The prevalence and consequences of prediabetic dysglycemia and undiagnosed diabetes is unknown in patients with heart failure (HF) and preserved ejection fraction (HFpEF) and has not been compared to heart failure and reduced ejection fraction (HFrEF). Methods: We examined the prevalence and outcomes associated with normoglycemia, prediabetic dysglycemia and diabetes (diagnosed and undiagnosed) among individuals with a baseline glycated hemoglobin (hemoglobin A1c, HbA1c) measurement stratified by HFrEF or HFpEF in the Candesartan in Heart failure Assessment of Reduction in Mortality and morbidity programme (CHARM). We studied the primary outcome of HF hospitalization or cardiovascular (CV) death, and all-cause death, and estimated hazard ratios (HR) by use of multivariable Cox regression models. Results: HbA1c was measured at baseline in CHARM patients enrolled in the USA and Canada and was available in 1072/3023 (35%) of patients with HFpEF and 1578/4576 (34%) patients with HFrEF. 18 and 16% had normoglycemia (HbA1c &lt; 6.0), 20 and 22% had prediabetes (HbA1c 6.0–6.4), respectively. Finally among patients with HFpEF 22% had undiagnosed diabetes (HbA1c &gt; 6.4), and 40% had known diabetes (any HbA1c), with corresponding prevalence among HFrEF patients being 26 and 35%. The rates of both clinical outcomes of interest were higher in patients with undiagnosed diabetes and prediabetes, compared to normoglycemic patients, irrespective of HF subtype, and in general higher among HFrEF patients. For the primary composite outcome among HFpEF patients, the HRs were 1.02 (95% CI 0.63–1.65) for prediabetes, HR 1.18 (0.75–1.86) for undiagnosed diabetes and 2.75 (1.83–4.11) for known diabetes, respectively, p value for trend across groups &lt; 0.001. Dysglycemia was also associated with worse outcomes in HFrEF. Conclusions: These findings confirm the remarkably high prevalence of dysglycemia in heart failure irrespective of ejection fraction phenotype, and demonstrate that dysglycemia is associated with a higher risk of adverse clinical outcomes, even before the diagnosis of diabetes and institution of glucose lowering therapy in patients with HFpEF as well as HFrEF

Therapeutic potential of the renin angiotensin system in ischaemic stroke

The renin angiotensin system (RAS) consists of the systemic hormone system, critically involved in regulation and homeostasis of normal physiological functions [i.e. blood pressure (BP), blood volume regulation], and an independent brain RAS, which is involved in the regulation of many functions such as memory, central control of BP and metabolic functions. In general terms, the RAS consists of two opposing axes; the ‘classical axis’ mediated primarily by Angiotensin II (Ang II), and the ‘alternative axis’ mediated mainly by Angiotensin-(1–7) (Ang-(1–7)). An imbalance of these two opposing axes is thought to exist between genders and is thought to contribute to the pathology of cardiovascular conditions such as hypertension, a stroke co-morbidity. Ischaemic stroke pathophysiology has been shown to be influenced by components of the RAS with specific RAS receptor antagonists and agonists improving outcome in experimental models of stroke. Manipulation of the two opposing axes following acute ischaemic stroke may provide an opportunity for protection of the neurovascular unit, particularly in the presence of pre-existing co-morbidities where the balance may be shifted. In the present review we will give an overview of the experimental stroke studies that have investigated pharmacological interventions of the RAS