Renin Production by Juxtaglomerular Cell Tumors and Clear Cell Renal Cell Carcinoma and the Role of Angiotensin Signaling Inhibitors

OBJECTIVE

To profile juxtaglomerular cell tumors (JXG) and histologic mimics by analyzing renin expression; to identify non-JXG renin-producing tumors in The Cancer Genome Atlas (TCGA) data sets; and to define the prevalence of hypertension (HTN) and patient outcomes with angiotensin signaling inhibitor (ASI) use in tumors of interest.

PATIENTS AND METHODS

Thirteen JXGs and 10 glomus tumors (GTs), a histologic mimic, were evaluated for clinicopathologic features; TCGA data were analyzed to identify non-JXG renin-overexpressing tumors. An institutional registry was queried to determine the incidence of HTN, the use of ASIs in hypertensive patients, and the impact of ASIs on outcomes including progression-free survival (PFS) in a tumor type with high renin expression (clear cell renal cell carcinoma [CC-RCC] diagnosed between January 1, 2005, and December 31, 2012).

RESULTS

We found an association between renin production and HTN in JXG compared with GT. Analysis of TCGA data found that a subset of CC-RCCs overexpress renin relative to 29 other tumor types. Furthermore, analysis of our institutional registry revealed a high prevalence (64%) of HTN among 1203 patients treated with radical or partial nephrectomy for nonmetastatic CC-RCC. On multivariable Cox regression, patients with HTN treated with ASIs (34%) had improved PFS (hazard ratio, 0.76; 95% CI, 0.57 to 1.00; P=.05) compared with patients with HTN not treated with ASIs (30%).

CONCLUSION

The identification of renin expression in a subset of CC-RCC may provide a biologic rationale for the high prevalence of HTN and improved PFS with ASI use in hypertensive patients with nonmetastatic CC-RCC.

Polyphenolic Composition and in Vitro Antihypertensive and Anti-Inflammatory Effects of Cuphea lindmaniana and Cuphea urbaniana

The present study investigates the chemical composition, anti-inflammatory, and antihypertensive activities, in vitro, from extracts of Cuphea lindmaniana and Cuphea urbaniana leaves. The extraction was performed ultrasound-assisted, and UHPLC/MS analysis was in positive mode ionization. The anti-inflammatory activity of the extracts and miquelianin were assayed at concentrations 0.001-10 μg/mL by chemotaxis on rat polymorphonuclear neutrophils. The antihypertensive activity was performed by angiotensin-converting enzyme (ACE) inhibition. From the nineteen proposed compounds, six of them are described for the first time in this genus. The extracts displayed antichemotactic effect with a reduction of 100 % of the neutrophil migration, in vitro, in most concentrations. The ACE-inhibition presented results ranging from 19.58 to 22.82 %. In conclusion, C. lindmaniana and C. urbaniana extracts contain a rich diversity of flavonoids and display in vitro anti-inflammatory and antihypertensive potential. Thus, this study could serve as a scientific baseline for further investigation, on developmental novel products with therapeutic actions.

Polyphenolic Composition and in Vitro Antihypertensive and Anti-Inflammatory Effects of Cuphea lindmaniana and Cuphea urbaniana

The present study investigates the chemical composition, anti-inflammatory, and antihypertensive activities, in vitro, from extracts of Cuphea lindmaniana and Cuphea urbaniana leaves. The extraction was performed ultrasound-assisted, and UHPLC/MS analysis was in positive mode ionization. The anti-inflammatory activity of the extracts and miquelianin were assayed at concentrations 0.001-10 μg/mL by chemotaxis on rat polymorphonuclear neutrophils. The antihypertensive activity was performed by angiotensin-converting enzyme (ACE) inhibition. From the nineteen proposed compounds, six of them are described for the first time in this genus. The extracts displayed antichemotactic effect with a reduction of 100 % of the neutrophil migration, in vitro, in most concentrations. The ACE-inhibition presented results ranging from 19.58 to 22.82 %. In conclusion, C. lindmaniana and C. urbaniana extracts contain a rich diversity of flavonoids and display in vitro anti-inflammatory and antihypertensive potential. Thus, this study could serve as a scientific baseline for further investigation, on developmental novel products with therapeutic actions.

Should COVID-19 Concern Nephrologists? Why and to What Extent? The Emerging Impasse of Angiotensin Blockade

Here, we review the most recent findings on the effects of SARS-CoV-2 infection on kidney diseases, including acute kidney injury, and examine the potential effects of ARBs on the outcomes of patients with COVID-19. Lastly, we discuss the clinical management of COVID-19 patients with existing chronic renal disorders, particularly those in dialysis and with kidney transplants.

Protective effects of tribulus terrestris extract and angiotensin blockers on testis steroidogenesis in copper overloaded rats

The rational of the current study was to assess whether Tribulus terrestris extract (TTE) could alleviate long-term copper (Cu) overload-induced testicular dysfunction compared to enalapril and losartan. Rats were administered either vehicle (control group, n = 10) or copper sulfate pentahydrate (CuSO₄·5H₂O, 200 mg/kg, p.o) for 90 days (n = 40). Cu-treated rats were randomized into four equal groups. One group was left untreated (Cu group) while the remaining three groups were daily co-treated with one of the following treatments along with CuSO4: TTE (10 mg/kg, p.o); enalapril (30 mg/kg, p.o); losartan (10 mg/kg, p.o). Excess Cu intake resulted in Cu overload coupled with a significant elevation in systolic blood pressure and serum angiotensin II levels along with a reduction in serum nitric oxide level. All concomitant treatments led to an alleviation of such deleterious effects. However, only losartan failed to ameliorate angiotensin II elevation. Additionally, all treatments protected the testes against Cu-overload-elicited zinc depletion and oxidative stress. Regarding reproductive function, the relative weights of testes, serum levels of testosterone and luteinizing hormone; the expression of steroidogenic genes; the protein levels of angiotensin II type 1 receptor and angiotensin converting enzyme 1, in addition to its activity, they were significantly reduced. Amongst all treatments, only TTE and E were able to revert these reproductive changes. In conclusion TTE and E were able to protect against Cu overload-induced impairment of testicular steroidogenesis. Thus, they might be considered as prophylactic drugs of choice against hypertension and testicular dysfunction to ameliorate Cu overload risk.

Suppression of angiotensin II-induced pathological changes in heart and kidney by the caveolin-1 scaffolding domain peptide

Dysregulation of the renin-angiotensin system leads to systemic hypertension and maladaptive fibrosis in various organs. We showed recently that myocardial fibrosis and the loss of cardiac function in mice with transverse aortic constriction (TAC) could be averted by treatment with the caveolin-1 scaffolding domain (CSD) peptide. Here, we used angiotensin II (AngII) infusion (2.1 mg/kg/day for 2 wk) in mice as a second model to confirm and extend our observations on the beneficial effects of CSD on heart and kidney disease. AngII caused cardiac hypertrophy (increased heart weight to body weight ratio (HW/BW) and cardiomyocyte cross-sectional area); fibrosis in heart and kidney (increased levels of collagen I and heat shock protein-47 (HSP47)); and vascular leakage (increased levels of IgG in heart and kidney). Echocardiograms of AngII-infused mice showed increased left ventricular posterior wall thickness (pWTh) and isovolumic relaxation time (IVRT), and decreased ejection fraction (EF), stroke volume (SV), and cardiac output (CO). CSD treatment (i.p. injections, 50 μg/mouse/day) of AngII-infused mice significantly suppressed all of these pathological changes in fibrosis, hypertrophy, vascular leakage, and ventricular function. AngII infusion increased β1 and β3 integrin levels and activated Pyk2 in both heart and kidney. These changes were also suppressed by CSD. Finally, bone marrow cell (BMC) isolated from AngII-infused mice showed hyper-migration toward SDF1. When AngII-infused mice were treated with CSD, BMC migration was reduced to the basal level observed in cells from control mice. Importantly, CSD did not affect the AngII-induced increase in blood pressure (BP), indicating that the beneficial effects of CSD were not mediated via normalization of BP. These results strongly indicate that CSD suppresses AngII-induced pathological changes in mice, suggesting that CSD can be developed as a treatment for patients with hypertension and pressure overload-induced heart failure.

Effect of Renin-Angiotensin Blockers on Left Ventricular Remodeling in Severe Aortic Stenosis

Studies have shown that medical therapy with renin-angiotensin blockers (RABs) may benefit patients with aortic stenosis (AS). However, its use and efficacy remains controversial, including in patients with low flow (LF) with preserved left ventricular ejection fraction (LVEF). We examined the effects of RAB use on LV remodeling in patients with severe AS with preserved LVEF, analyzing the differential effects in patients with LF compared with normal flow (NF). This is a retrospective study of 428 consecutive subjects from 2005 to 2014 with echocardiographic diagnosis of severe AS and preserved LVEF. Clinical and echocardiographic parameters were systematically collected and analyzed. Two hundred forty-two (57%) patients had LF. Sixty-four LF patients (26%) were treated with RAB. Patients on RAB treatment had a higher incidence of hyperlipidemia (69% vs 44%) and diabetes mellitus (53% vs 34%). Severity of AS in terms of valve area, transvalvular mean pressure gradient, and aortic valve resistance were similar between both groups as was the degree of LV diastolic function. The RAB group demonstrated significantly lower LV mass index with a correspondingly lower incidence of concentric LV hypertrophy. Regardless of the duration of RAB therapy, patients had increased odds of having a preserved LV mass index compared with those without RAB therapy. In conclusion, RAB therapy may be associated with less LV pathological remodeling and have a role in delaying patients from developing cardiovascular complications of AS.

Angiotensin system inhibitors and survival outcomes in patients with metastatic renal cell carcinoma

PURPOSE

The renin-angiotensin system may play a role in carcinogenesis. The purpose of this study was to evaluate the impact of angiotensin system inhibitors (ASI) on outcomes in metastatic renal cell carcinoma (mRCC) patients treated in the targeted therapy era.

EXPERIMENTAL DESIGN

We conducted a pooled analysis of mRCC patients treated on phase II and III clinical trials. Statistical analyses were performed using Cox regression adjusted for several risk factors and the Kaplan-Meier method.

RESULTS

A total of 4,736 patients were included, of whom 1,487 received ASIs and 783 received other antihypertensive agents. Overall, ASI users demonstrated improved overall survival (OS) compared with users of other antihypertensive agents (adjusted HR, 0.838, P = 0.0105, 26.68 vs. 18.07 months) and individuals receiving no antihypertensive therapy (adjusted HR, 0.810, P = 0.0026, 26.68 vs. 16.72 months). When stratified by therapy type, a benefit in OS was demonstrated in ASI users compared with nonusers in individuals receiving VEGF therapy (adjusted HR, 0.737, P < 0.0001, 31.12 vs. 21.94 months) but not temsirolimus or IFNα. An in vitro cell viability assay demonstrated that sunitinib in combination with an ASI significantly decreased RCC cell viability compared with control at physiologically relevant doses. This effect was not observed with either agent alone or with other non-ASI antihypertensives or temsirolimus.

CONCLUSIONS

In the largest analysis to date, we demonstrate that ASI use improved survival in mRCC patients treated in the targeted therapy era. Further studies are warranted to investigate the mechanism underlying this interaction and verify our observations to inform clinical practice.

Renin-angiotensin-aldosterone-blockade is associated with decreased use of antidepressant therapy in patients with type 1 diabetes and diabetic nephropathy

Hypertension and depression are frequent comorbidities of diabetes. Studies suggest that antihypertensive medication affecting the renin-angiotensin-aldosterone system (RAAS) might also relieve depression. Whether this is also seen in patients with type 1 diabetes is not known. We therefore studied whether use of RAAS-modifying medication is associated with reduced antidepressant use in type 1 diabetes. In all, 1,705 participants in the FinnDiane Study were included (57 % men, mean age 46 ± 11 years). Data on medications were obtained from the Drug Prescription Register. Based on their albumin excretion rate (AER), the patients were classified as having normal AER, microalbuminuria, or macroalbuminuria. Diabetic nephropathy was defined as macroalbuminuria or end-stage renal disease (dialysis or renal transplant). A total of 8.4 and 10.9 % of patients with and without RAAS-modifying medication, respectively, had antidepressant medication purchases (NS). In logistic regression analysis, after adjusting for potential confounding factors, use of RAAS-modifying medication was not associated with antidepressant purchases. However, when patients with and without diabetic nephropathy were analyzed separately, RAAS-modifying medication was associated with lower frequency of antidepressant purchases among patients with established diabetic nephropathy. In conclusion, use of RAAS-modifying medication may improve mood in patients with type 1 diabetes and established diabetic nephropathy.

Angiotensin inhibition enhances drug delivery and potentiates chemotherapy by decompressing tumour blood vessels

Cancer and stromal cells actively exert physical forces (solid stress) to compress tumour blood vessels, thus reducing vascular perfusion. Tumour interstitial matrix also contributes to solid stress, with hyaluronan implicated as the primary matrix molecule responsible for vessel compression because of its swelling behaviour. Here we show, unexpectedly, that hyaluronan compresses vessels only in collagen-rich tumours, suggesting that collagen and hyaluronan together are critical targets for decompressing tumour vessels. We demonstrate that the angiotensin inhibitor losartan reduces stromal collagen and hyaluronan production, associated with decreased expression of profibrotic signals TGF-β1, CCN2 and ET-1, downstream of angiotensin-II-receptor-1 inhibition. Consequently, losartan reduces solid stress in tumours resulting in increased vascular perfusion. Through this physical mechanism, losartan improves drug and oxygen delivery to tumours, thereby potentiating chemotherapy and reducing hypoxia in breast and pancreatic cancer models. Thus, angiotensin inhibitors -inexpensive drugs with decades of safe use - could be rapidly repurposed as cancer therapeutics.

Meta-analysis of randomized trials of angioedema as an adverse event of renin-angiotensin system inhibitors

Angioedema is a rare, potentially life-threatening adverse event of renin-angiotensin system inhibitors. The objective of the present study was to determine the risk of angioedema from randomized clinical trials. A PubMed/CENTRAL/EMBASE search was made for randomized clinical trials from 1980 to October 2011 in patients on angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), or direct renin inhibitor (DRI). Trials with a total number of patients ≥100 and a duration of ≥8 weeks were included for analysis. Incidence of angioedema was pooled by weighing the incident rate of each trial by the inverse of the variance. Twenty-six trials with 74,857 patients in the ACE inhibitor arm with 232,523 person-years of follow-up, 19 trials with 35,479 patients on ARB with 122,293 person-years of follow-up, and 2 trials with 5,141 patients on DRI with 1,735 person-years of follow-up met the inclusion criteria and were included in the analysis. In head-to-head comparison in 7 trials, risk of angioedema with ACE inhibitors was 2.2 times higher than with ARBs (95% confidence interval [CI] 1.5 to 3.3). With ACE inhibitors and ARBs, incidence of angioedema was higher in heart failure trials compared to hypertension or coronary artery disease trials without heart failure (p <0.0001). Weighted incidence of angioedema with ACE inhibitors was 0.30% (95% CI 0.28 to 0.32) compared to 0.11% (95% CI 0.09 to 0.13) with ARBs, 0.13% (95% CI 0.08 to 0.19) with DRIs, and 0.07% with placebo (95% CI 0.05 to 0.09). In conclusion, incidence of angioedema with ARBs and DRI was <1/2 than that with ACE inhibitors and not significantly different from placebo. Incidence of angioedema was higher in patients with heart failure compared to those without heart failure with ACE inhibitors and ARBs.

Effect of Tulbaghia violacea on the blood pressure and heart rate in male spontaneously hypertensive Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tulbaghia violacea Harv. (Alliaceae) is a small bulbous herb which belongs to the family Alliaceae, most commonly associated with onions and garlic. In South Africa, this herb has been traditionally used in the treatment of various ailments, including fever, colds, asthma, paralysis, hypertension and stomach problems. The aim of this study was to evaluate the effect of methanol leaf extracts (MLE) of Tulbaghia violacea on the blood pressure (BP) and heart rate (HR) in anaesthetized male spontaneously hypertensive rats; and to find out the mechanism(s) by which it acts.

MATERIALS AND METHODS

The MLE of Tulbaghia violacea (5-150mg/kg), angiotensin I human acetate salt hydrate (ang I, 3.1-100μg/kg), angiotensin II human (ang II, 3.1-50μg/kg), phenylephrine hydrochloride (phenylephrine, 0.01-0.16mg/kg) and dobutamine hydrochloride (dobutamine, 0.2-10.0μg/kg) were infused intravenously, while the BP and HR were measured via a pressure transducer connecting the femoral artery and the Powerlab.

RESULTS

Tulbaghia violacea significantly (p<0.01) reduced the systolic, diastolic, and mean arterial BP; and HR dose-dependently. Ang I, ang II, phenylephrine and dobutamine all increased the BP dose-dependently. The hypertensive effect of ang I and the HR-increasing effect of dobutamine were significantly (p<0.01) decreased by their co-infusion with Tulbaghia violacea (60mg/kg). However, the co-infusion of ang II or phenylephrine with Tulbaghia violacea (60mg/kg) did not produce any significant change in BP or HR when compared to the infusion of either agent alone in the same animal.

CONCLUSIONS

Tulbaghia violacea reduced BP and HR in the SHR. The reduction in BP may be due to actions of the MLE on the ang I converting enzyme (ACE) and β(1) adrenoceptors.

Angiotensin system inhibitors and outcome of sunitinib treatment in patients with metastatic renal cell carcinoma: a retrospective examination

BACKGROUND

Sunitinib is a standard treatment for metastatic renal cell carcinoma. Angiotensin system inhibitors, including angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, are widely used in hypertension, kidney disease and heart failure. Data suggests that they may inhibit tumourigenesis.

AIMS

To study the effect of angiotensin system inhibitors on sunitinib treatment outcome in metastatic renal cell carcinoma.

METHODS

We performed a retrospective study of an unselected cohort of patients with metastatic renal cell carcinoma who were treated with sunitinib. Patients were divided into angiotensin system inhibitors users (group 1) and non-users (group 2). The effect of angiotensin system inhibitors on objective response, time to disease progression and overall survival, was tested with adjustment for known confounding risk factors through logistic regression model and Cox regression model.

RESULTS

Between 2004 and 2010, 127 patients with metastatic renal cell carcinoma were treated with sunitinib, 44 group 1 and 83 group 2. The groups were balanced regarding known clinicopathologic prognostic factors. Objective response was partial response/stable disease 86% versus 72% and progressive disease 14% versus 28% (p=0.07) in group 1 versus 2, respectively. Median progression free survival was 13 versus 6 months (HR 0.537, p=0.0055), and median overall survival 30 versus 23 months (HR 0.688, p=0.21), in favour of group 1.

CONCLUSIONS

Angiotensin system inhibitors may improve the outcome of sunitinib treatment in metastatic renal cell carcinoma. This should be investigated prospectively, and if validated applied in clinical practise and clinical trials.

[Pharmacological differences between inhibitor drugs of the renin-angiotensin aldosterone system]

The activation of the renin-angiotensin-aldosterone cascade is a mechanism that generates high blood pressure. The structure has been identified and can be blocked through specific enzymatic pathways or receptors. We have a diversity of medications that act on this system. It is useful to develop the skill in clinical practice for selecting a drug from a wide variety. Renin-angiotensin system inhibitors share many pharmacological and pharmacokinetic characteristics but not all them are equivalent. Knowledge based on scientific evidence allows the clinician to choose the ideal drug for each patient.

Angiotensin inhibition and longevity: a question of hydration

With the advancement of medical and investigative science, it is somewhat surprising that although it is possible to stabilise medical patients with hypertension and the associated kidney dysfunction, obesity, diabetes and even cancer, there is still no clear method of significantly reducing these chronic disease pathologies, and thus, extending life expectancy. There is one hormone common to these pathologies, the antagonism of which goes some way to clinical improvements, and this is angiotensin, which is released during hypovolaemia. Angiotensin antagonists are used to treat many of these pathologies, and it has been shown in the obesity literature that angiotensin antagonists decrease weight, but also increase the drinking of water. Increased cellular hydration, and hence, improved mitochondrial metabolism could be one of the mechanisms for the reduction in weight seen in these studies, as well as for reducing the other pathologies, all showing metabolic dysfunction. It appears that the application of straightforward physiological regulation might be an appropriate medical approach to the prevention of hypertension, kidney disease, obesity, diabetes and cancer, and thus, to an increased life expectancy.

Complete remission of nephrotic syndrome in an infant with focal segmental glomerulosclerosis: is it renin-angiotensin blockade?

Nephrotic syndrome presenting in the first year of life is often challenging, with substantial risk of progression to end-stage renal disease (ESRD). Focal segmental glomerulosclerosis (FSGS) comprises up to 20% of biopsy-proven glomerular disease in children and adults. We report on a 9-month-old infant who presented with nephrotic syndrome, hypertension and progressive deterioration of renal function due to FSGS. As immunosuppressive agents are often unsuccessful in treating this condition, we adopted renoprotection as the mainstay treatment for this patient, through rigorous control of blood pressure and proteinuria with a multi-drug regimen including renin-angiotensin axis blockade. Initially, there was partial improvement, with a gradual decline in proteinuria and a concomitant rise in the glomerular filtration rate, before the disease eventually passed into complete clinical and laboratory remission. We speculate that infants with steroid-resistant nephrotic syndrome due to FSGS may benefit from tight control of hypertension, mainly though early blockade of the renin-angiotensin axis. We believe that its renoprotecive mechanism counteracts the deleterious effects of both hypertension and proteinuria, thereby not only preventing progressive renal disease, but even paving the way for a remission, as in our patient. To the best of our knowledge, this is the first report of an infant with nephrotic syndrome (NS) due to FSGS that passed into complete remission while the patient was on renoprotective measures including the use of angiotensin-converting enzyme inhibitors (ACEis).

Renin-angiotensin system inhibitors in proteinuric chronic kidney disease

Renin-angiotensin inhibitors are effective in slowing the progression of chronic proteinuric kidney disease. These medicines should be used in preference to anti-hypertensives that do not provide renoprotection.

Blockades of angiotensin and aldosterone reduce osteopontin expression and interstitial fibrosis infiltration in rats with myocardial infarction

BACKGROUND

It has been reported that osteopontin has an important role in cardiac fibrosis and remodeling. However, its direct mechanisms remain unclear. The purpose of this study was to investigate the role of angiotensin and aldosterone blockades in cardiac osteopontin expression associated with cardiac remodeling in myocardial infarcted (MI) rats.

METHODS

Fifty SD rats that survived 24 hours after ligating left anterior descending coronary artery were randomly divided into three groups: MI-saline group (n = 15, 5 ml/d), MI-perindopril group (n = 18, perindopril 2 mgxkg(-1)d(-1)) and MI-spironolacton (n = 17, spironolacton 20 mgxkg(-1)xd(-1)). A sham operation group (n = 15) was selected as non-infarcted control. At 6 weeks after treatment, hemodynamic pararmeters and left ventricular function were measured with catheterization, interstitial fibrosis infiltration and cardiomyocyte diameters were evaluated histologically. Myocardium osteopontin protein expression level in the non-infarcted myocardium was detected by Western blotting.

RESULTS

No osteopontin protein was detected in the myocardium of sham-operation rats. High levels of osteopontin protein expression were detected in the MI-saline rats, but the levels were suppressed in the MI-perindopril and MI-spironolacton rats at 6 weeks following MI (P < 0.01, respectively). Compared with the sham operation group, all rats in the MI group showed marked interstitial fibrosis infiltration in the non-infarction area, higher ventricular weight/body weight ratio, significantly increased cardiomyocyte diameter (P < 0.01, respectively), and developed significant systolic and diastolic dysfunction as indicated by decreased left ventricular systolic pressure (LVSP) and +/-dp/dt, as well as increased left ventricular end-diastolic pressure (LVEDP) (P < 0.01, respectively). Angiotensin and aldosterone blockades partly prevented cardiac fibrosis and systolic and diastolic dysfunction (P < 0.01, respectively).

CONCLUSION

Treatment with angiotensin and aldosterone blockades inhibits expression of osteopontin in the non-infarcted myocardium and prevents cardiac remodeling following MI.

Angiotensin inhibition in renovascular disease: a population-based cohort study

BACKGROUND

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers effectively reduce blood pressure in patients with renovascular disease (RVD); yet, randomized cardiovascular prevention trials of these drugs typically exclude individuals with this condition.

PATIENTS AND METHODS

We studied the association of renin-angiotensin system inhibition with prognosis in a population-based cohort comprising 3,570 patients with RVD in Ontario, Canada; slightly more than half (n = 1,857, 53%) were prescribed angiotensin inhibitors. The primary outcome was the composite of death, myocardial infarction, or stroke. Secondary outcomes included individual cardiovascular and renal events.

RESULTS

Patients receiving angiotensin inhibitors had a significantly lower risk for the primary outcome during follow-up (10.0 vs 13.0 events per 100 patient-years at risk, multivariable adjusted hazard ratio [HR] 0.70, 95% CI 0.59-0.82). In addition, hospitalization for congestive heart failure (HR 0.69, 95% CI 0.53-0.90), chronic dialysis initiation (HR 0.62, 95% CI 0.42-0.92), and mortality (HR 0.56, 95% CI 0.47-0.68) was lower in treated patients. Conversely, patients receiving angiotensin inhibitors were significantly more likely to be hospitalized for acute renal failure during follow-up (HR 1.87, 95% CI 1.05-3.33; 1.2 vs 0.6 events per 100 patient-years at risk).

CONCLUSIONS

These data emphasize the high vascular risk of RVD and suggest that angiotensin inhibitors may improve prognosis in this setting at the expense of acute renal toxicity. If the latter are selected in the management of RVD, renal function parameters should be assiduously followed.

Modulation of glomerulosclerosis

Regardless of the initial injury, the long-term consequence for the patient depends upon the ensuing balance of profibrotic vs reparative modulators activated. The glomerulus has some capacity for repair. Even when sclerosis has developed with accumulation of extracellular matrix, this lesion may be remodeled, with a change in balance between profibrotic and antifibrotic and collagen synthesis vs proteolytic mediators. We will focus here on the interplay between mediators of fibrosis and reparative mechanisms and potential regression of fibrosis. Based on the clinical efficacy of interventions that inhibit angiotensin, we will focus on factors related to the renin-angiotensin system.

[Drug treatment of chronic heart failure]

Drug treatment of chronic heart failure is undergoing continuous modifications according to the data of new trials. Treatment has to be adjusted to current guidelines. The state of the art of medical treatment of chronic heart failure is addressed in this report.

Effects of insulin replacements, inhibitors of angiotensin, and PKCbeta's actions to normalize cardiac gene expression and fuel metabolism in diabetic rats

High-density oligonucleotide arrays were used to compare gene expression of rat hearts from control, untreated diabetic, and diabetic groups treated with islet cell transplantation (ICT), protein kinase C (PKC)beta inhibitor ruboxistaurin, or ACE inhibitor captopril. Among the 376 genes that were differentially expressed between untreated diabetic and control hearts included key metabolic enzymes that account for the decreased glucose and increased free fatty acid utilization in the diabetic heart. ICT or insulin replacements reversed these gene changes with normalization of hyperglycemia, dyslipidemia, and cardiac PKC activation in diabetic rats. Surprisingly, both ruboxistaurin and ACE inhibitors improved the metabolic gene profile (confirmed by real-time RT-PCR and protein analysis) and ameliorated PKC activity in diabetic hearts without altering circulating metabolites. Functional assessments using Langendorff preparations and (13)C nuclear magnetic resonance spectroscopy showed a 36% decrease in glucose utilization and an impairment in diastolic function in diabetic rat hearts, which were normalized by all three treatments. In cardiomyocytes, PKC inhibition attenuated fatty acid-induced increases in the metabolic genes PDK4 and UCP3 and also prevented fatty acid-mediated inhibition of basal and insulin-stimulated glucose oxidation. Thus, PKCbeta or ACE inhibitors may ameliorate cardiac metabolism and function in diabetes partly by normalization of fuel metabolic gene expression directly in the myocardium.

Renin-angiotensin-system blockade in the prevention of diabetes

Type 2 diabetes often occurs in association with hypertension and cardiovascular disease, and markedly increases cardiovascular risk. Strategies to reduce the incidence of diabetes in patients with cardiovascular disease or at high risk for such disease are therefore important. Certain classes of antihypertensive agents, namely the thiazide diuretics and beta-blockers, have an adverse impact on the metabolic profile and increase the risk for new-onset diabetes in hypertensive subjects. In contrast, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), which are blockers of the renin-angiotensin system (RAS), have been shown to increase insulin sensitivity. They may also reduce the risk of diabetes in patients with hypertension or cardiovascular disorders. Some of the evidence in favour of ACE inhibitors and ARBs has come from studies with active comparators that have potential adverse metabolic effects. However, the Candesartan in Heart failure-Assessment of Reduction in Mortality and morbidity (CHARM) programme demonstrated that the ARB candesartan reduced the incidence of diabetes in heart failure patients in comparison to placebo. The mechanisms responsible for the beneficial effects of RAS blockade remain to be established. Nevertheless, a treatment that can control hypertension and reduce the risk of onset of type 2 diabetes at the same time is certainly desirable.

Angiotensin blockade as sole treatment for proteinuric kidney disease in children

BACKGROUND

The traditional management of children with proteinuric kidney disease is treatment with high dose steroids regardless of comorbid conditions such as obesity. This study evaluated the effect of angiotensin blockade (AB) alone as the sole management of children with non-diabetic proteinuric kidney disease.

METHODS

Retrospective chart analysis was performed in 146 children. Seventeen were identified to have received angiotensin-converting enzyme inhibitor and/or angiotensin receptor blocker exclusively for management of proteinuria. Total proteinuria (Upr/cr), albuminuria (Ualb/cr), estimated glomerular filtration rate (eGFR), serum potassium and blood pressure were assessed at baseline and at 3-month intervals for over 24 months.

RESULTS

Mean age was 11.2+/-4.8 years with 12 females. Eleven of 17 patients (65%) were overweight or obese. There was a significant decline in total proteinuria and albuminuria after 3-6 months of AB therapy and a further decline with longer duration of treatment (P<0.001). Although single vs dual AB were similarly effective in lowering total proteinuria, dual therapy was more effective in lowering albuminuria (single 57+/-23% vs dual 71+/-15%; P<0.02). The eGFR decreased from 'hyperfiltration' levels prior to initiation of AB to normal at the end of the treatment period (145+/-41-111+/-17 ml/min/1.73 m2; P=0.01). Systemic blood pressures remained normal throughout the study period.

CONCLUSIONS

Angiotensin blockade alone appears to effectively control proteinuria and stabilize kidney function in children. This may provide an alternative to more toxic therapies, especially corticosteroids, in children with glomerular disorders such as those associated with obesity.

Prophylactic pharmacotherapy for migraine headaches

Migraine therapeutics are pharmacological, including acute and preventive, nonpharmacological and/or both. Preventive pharmacological strategies serendipitously were discovered to be effective and include drugs from various pharmacological classes (e.g., beta-adrenergic blocker, anticonvulsant, tricyclic antidepressants, serotonin receptor antagonist). Converging level I evidence and clinical experience support the use of the antidepressant amitriptyline, the anticonvulsants divalproex and topiramate, and the beta-adrenergic blockers propranolol, timolol, and metoprolol in migraine prevention. Other options for migraine prophylaxis exist, but the level of evidence in support of their use is not as robust. All of these drugs have varying degrees of adverse effects, some of which can limit their use. Balancing potential efficacy with risk of adverse effects, addressing patients' expectations and desires, complying with management recommendations, adequate follow up, and accurate assessment of treatment goals are key to migraine prevention. Finally, future migraine-preventive drugs likely will target migraine mechanisms more specifically, which undoubtedly will enhance the therapeutic index.

Alcoholism and neuropeptides: an update

As with other addictions, human alcoholism is characterised as a chronically relapsing condition. Consequently, the "holy grail" from a therapeutic viewpoint is the development of clinically effective, safe drugs that promote high compliance rates and prevent relapse. Here we discuss the potential of therapeutics targeting neuropeptide systems implicated in aberrant alcohol-seeking behaviour. Clearly, much of the data so far available comes from pre-clinical studies; however, one of the first effective therapeutic strategies for alcoholism (still in use today) was the use of non-selective opioid receptor antagonists, such as naltrexone (Revia). In addition to opioid receptors, other neuropeptide receptors including those for corticotrophin releasing factor (CRF), neuropeptide Y and nociceptin may represent valid therapeutic targets to regulate alcohol consumption and the affective consequences of alcohol withdrawal.

Manipulating the angiotensin system--new approaches to the treatment of solid tumours

Angiotensin II (Ang II), a main effector peptide in the renin-angiotensin system (RAS), plays a fundamental role as a vasoconstrictor in controlling cardiovascular function and renal homeostasis. Ang II also acts as a growth promoter or angiogenic factor via type 1 angiotensin II receptors (AT1Rs) in certain tumour cell lines. Recent studies have shown the activation of the local RAS in various tumour tissues, including the abundant generation of Ang II by angiotensin-converting enzyme (ACE) and the upregulation of AT1R expression. Thus, considerable attention has been paid to the role of the RAS in cancer and its blockade as a new approach to the treatment of cancer. There is increasing evidence that the Ang II-AT1R system is involved in tumour growth, angiogenesis and metastasis in experimental models, suggesting the therapeutic potential of an ACE inhibitor and AT1R blocker, both of which have been used as antihypertensive drugs. In addition, specific Ang II-degrading enzymes are expressed in tumours and play a regulatory role in cell proliferation and invasion. This review focuses on the role of the Ang II-AT1R system in solid tumours, particularly in the progression of gynaecological cancer, and presents the clinical potential of manipulating the angiotensin system as a novel and promising strategy for cancer treatment.

[Simvastatin inhibits hypertension-induced cardiac hypertrophy in rats through activation of heme oxygenase-1/carbon monoxide pathway]

To investigate the anti-cardiac hypertrophic mechanism of statins, thirty-eight male Wistar rats were randomly allocated to four groups. Rats in model group received nitric oxide synthase inhibitor, N-nitro-L-arginine (L-NNA) 15 mg/(kg.d) by peritoneal injection. Rats in simvastatin treatment groups were given simultaneously L-NNA as those in model group and simvastatin 5 or 30 mg/(kg.d) intragastrically respectively. Rats in control group received the same volume of normal sodium. Left ventricular function, left ventricular mass index (LVMI), the content of brain natriuretic peptide (BNP) in plasma and myocardium, myocardial hydroxyproline and heme oxygenase activity were determined after 6 weeks. The results showed that rats in model group developed significant cardiac hypertrophy associated with reduced left ventricular function compared with the control group. However, compared with the model group, L-NNA-induced cardiac hypertrophy of rats was significantly relieved in simvastatin treatment groups, associated with improved left ventricular function, decreased LVMI, lower BNP levels in plasma and myocardium, lower content of myocardial hydroxyproline, and increased myocardial heme oxygenase (HO) activity. In cultured rat neonatal cardiomyocytes, simvastatin (30 or 100 mumol/L) significantly increased heme oxygenase-1 (HO-1) mRNA expression, HO activity as well as the production of CO in cardiomyocytes. Cultured with zinc protoporphyrin, a HO inhibitor, or simvastatin alone did not change [(3)H]leucine uptake of cardiomyocytes. However, cocultured with simvastatin significantly inhibited the cardiomyocyte [(3)H]leucine uptake induced by angiotensin II in a concentration-dependent manner. Cotreatment with zinc protoporphyrin significantly abolished the suppressive effect of simvastatin on cardiomyocyte [(3)H]leucine uptake. These data suggest that the activation of HO-1/CO pathway may be one of the important mechanisms by which statins inhibit cardiac hypertrophy caused by hypertension.

Qualification of arterial stiffness as a risk factor to the progression of chronic kidney diseases

BACKGROUND

Reflection pressure may influence the clinical course of chronic kidney diseases (CKDs). The relationship between the augmentation index (AI) and progression of non-diabetic CKDs was characterized.

METHODS

Ninety-nine patients were enrolled into the study. Pulse wave form analysis was performed to determine AI that assesses arterial stiffness.

RESULTS

In a cross-sectional study, a multiple regression analysis found that AI correlated positively to age and weight, and negatively to height and heart rate (R(2) = 0.50). Furthermore, echocardiography was performed in 51 patients who gave their consent. In male patients under angiotensin inhibition, left ventricular mass index increased as AI was elevated (r = 0.33, slope = 0.85 +/- 0.30 g/m(2)/%, p < 0.05, n = 23). A prospective study was performed in 41 patients who consented to having their creatinine clearance measured repeatedly. In the patients with angiotensin inhibition a higher basal AI resulted in a greater annual decrease in creatinine clearance (r = -0.52, slope = -0.43 +/- 0.14 ml/min/year/%, p < 0.01, n = 27).

CONCLUSION

The present data indicate that AI as well as angiotensin contribute to the development of left ventricular hypertrophy. Furthermore, our results suggest that in addition to angiotensin, AI is a risk factor of progression of non-diabetic CKDs.

Melanin-concentrating hormone enhances sucrose intake

Melanin-concentrating hormone (MCH) is known to be an important regulator for feeding and energy balance. MCH was recently reported to stimulate water intake independent of food intake. The purpose of the present study is to examine the dipsogenic response of MCH with special emphasis on sweetened beverages, the preference for which is well documented in diabetic animals. Our results showed that intracerebroventricular injection of MCH acutely increased food as well as water intake. Human (h)MCH and salmon (s)MCH increased water intake independent of food intake, which was not suppressed by angiotensin antagonists. hMCH and sMCH significantly increased both sucrose solution and food intake; on the other hand, agouti-related protein (AgRP) stimulated food but not sucrose intake when provided simultaneously. MCH-treated rats significantly increased the ingestion of sucrose and glucose solution, but not of saccharin, indicating that MCH-induced dipsogenic response is more related to caloric content than sweet taste per se. Significant correlation was observed between the sucrose intake and the mRNA expression of MCH and MCHR1 in normal rats. These results indicate that MCH may be an important regulator of sugar intake in normal as well as in obese diabetic animals.

Influence of brain angiotensin on thermoregulation and hydromineral balance during pregnancy in rats

During mammalian pregnancy, body temperature decreases and there are changes in fluid and electrolyte balance. Angiotensin signaling mechanisms in the brain have been shown to influence thermoregulation and body fluid balance in the nonpregnant state. We hypothesized that brain angiotensin is also implicated in adjusting these physiological systems in the pregnant rat. We compared core temperature and fluid regulation in three groups of pregnant rats: untreated rats, rats receiving continuous infusion of an AT1 antagonist candesartan (5 μg·kg−1·day−1) into a lateral cerebral ventricle to block brain AT1 receptors, and rats receiving vehicle [artificial cerebrospinal fluid (aCSF)] vehicle. Untreated and aCSF-treated rats showed a decrease in colonic temperature (−0.5 and −0.8°C respectively) by day 20 of gestation. However, rats treated with candesartan had increased colonic temperature compared with baseline (+0.9°C), and their temperature was significantly higher on days 7 ( P < 0.05), 17 ( P < 0.05), and 20 ( P < 0.001) compared with the other groups (aCSF and untreated). Daily food and water intakes and body weight were not different between the three groups. Similarly, litter sizes and pup weights were equal in all groups. Finally, the expected decreases in plasma Na+ and osmolality during pregnancy were equivalent in all groups. This study suggests that brain angiotensin mediates the progressive decrease in body temperature that occurs during pregnancy. However, the changes in fluid balance associated with pregnancy are not dependent on brain angiotensin.

Processing of acidic proline-rich proprotein by human salivary gland convertase

Previously it was found that proproteins for basic and glycosylated salivary proline-rich proteins (PRP) were cleaved prior to secretion from cells by furin, a well-known convertase. In contrast proproteins for acidic PRPs are not cleaved by furin or other convertases. To investigate the convertase responsible for in vivo processing of acidic PRP proproteins, homogenates of human sublingual glands were fractionated by centrifugation at 10,000 x g and 100,000 x g and activity demonstrated in all fractions. The 100,000 x g pellet was fractionated into Golgi, smooth endoplasmic reticulum and microsomal fractions with the latter containing the enzyme. Subfractionation of the microsomes revealed that the activity was located in the membrane proteins. Since the microsomes contain components of the secretory pathway the enzyme in this fraction may be responsible for intracellular cleavage of the acidic PRP proprotein. The enzyme was active at alkaline pH. It was strongly inhibited by metal chelators indicating that it is a metalloprotease. It was not inhibited by an acid protease inhibitor, but partly inhibited by some serine protease inhibitors indicating that serine proteases may play a role in degradation. Co2+ and to some extent Zn2+ activated the enzyme, but it was strongly inhibited by Hg2+ and Cu2+ as well as the organomercurial p-chloromercuribenzenesulfonic acid. Thus it appears that the enzyme contains an important -SH group. These characteristics indicate that the convertase is related to a group of metal- and thiol-dependent proteases known as thimet oligopeptidases, but in contrast to the latter enzymes the sublingual convertase was not inhibited by angiotensin antagonists.

Randomized double-blind placebo-controlled study of an angiotensin immunotherapeutic vaccine (PMD3117) in hypertensive subjects

Immunization against components of the renin–angiotensin system offers a potential alternative to daily medication in some patients with hypertension or heart failure. Our primary objective was to determine whether a sustained antibody titre to Ang I (angiotensin I) can be achieved in hypertensive patients. The secondary objective was to determine whether the antibodies block the renin system. Patients (n=27) with essential hypertension responsive to an ACEi (angiotensin-converting enzyme inhibitor) or ARB (angiotensin blocker) were randomly assigned to receive three or four injections of the Ang I vaccine PMD3117 or aluminium hydroxide (Alhydrogel™) over a 6 week period. Antibody titre was measured prior to each injection and every 30 days until disappearance. Indices of renin blockade were changes in renin and aldosterone (blood and urine) and a within-patient comparison of the pre- and post-vaccination rise in 24 h ambulatory blood pressure after 2 weeks of withdrawal of ACEi or ARB. The anti-(Ang I) antibody titre rose from the second injection in both regimes and peaked on day 64. Median half-life was 85 (95% CI, 44 and 153) days (where CI is confidence interval). Vaccination did not influence blood pressure, but significantly blunted the fall in plasma renin following withdrawal of ACEi or ARB. At 42 days after the first injection, aldosterone excretion was decreased by PMD3117 to 6 (95% CI, 1 and 31)% of values in patients receiving Alhydrogel™ (P=0.012). In patients with essential hypertension, PMD3117 generated a prolonged antibody response to Ang I. Biochemical measurements show evidence of blockade of the renin system, but higher titres will be required to achieve a decrease in blood pressure.

Evidence for the role of angiotensin II biosynthesis in the rat internal anal sphincter tone

BACKGROUND & AIMS

The internal anal sphincter tone is important for anorectal continence. This study examined the role of angiotensin II as a neurohumoral signal for the myogenic tone in the internal anal sphincter.

METHODS

We determined the effect of angiotensin I, II, III, and IV and angiotensin-(1-7) on the basal tone of the rat internal anal sphincter smooth muscle before and after selective receptor antagonists and biosynthesis inhibitors. Selective pharmacological tools used were losartan (for the AT(1) receptor), PD123,319 (for AT(2)), A-779 [for angiotensin-(1-7)], captopril (for angiotensin-converting enzyme), and amastatin (for aminopeptidases A and N). Angiotensins were measured by using high-performance liquid chromatography/UV. Western blot studies were used to determine AT(1) and AT(2) receptors, ACE, and aminopeptidases A and N.

RESULTS

Angiotensin I, II, and III produced concentration-dependent contraction in the internal anal sphincter mediated by AT(1) receptors. However, in the higher concentrations (from 100 nM to 10 microM), angiotensin II showed an inhibitory effect via AT(2) receptors. Captopril (1 microM) inhibited the biosynthesis of angiotensin II in the internal anal sphincter, antagonized the contractile effects of angiotensin I, and, importantly, caused a decrease in the basal tone. Amastatin inhibited the effects of angiotensin II while augmenting those of angiotensin III. In contrast, angiotensin-(1-7) and angiotensin IV had only minor effects in the internal anal sphincter. Angiotensin I, II, and III; angiotensin-converting enzyme; aminopeptidase A and aminopeptidase n; at(1); and at(2) receptors were shown to be present in the internal anal sphincter.

CONCLUSIONS

Locally produced angiotensin II may partially regulate basal tone in the internal anal sphincter.

Angiotensin antagonism in patients with heart failure: ACE inhibitors, angiotensin receptor antagonists or both?

Chronic heart failure (CHF) is a major cause of morbidity and mortality in western society. It is now widely accepted that the renin-angiotensin-aldosterone system (RAAS) and, in particular, angiotensin II (A-II) play a key role in the pathophysiology of CHF. Large-scale clinical trials have demonstrated that inhibitors of angiotensin-converting enzyme (ACE), the principal enzyme responsible for A-II production, improve symptoms and survival in patients with CHF. This enzyme is also responsible for the breakdown of the vasodilator hormone bradykinin. Administration of ACE inhibitors is associated with increased plasma bradykinin levels and this is thought to contribute to the vascular changes associated with ACE inhibitor therapy. However, RAAS inhibition with ACE inhibitors remains incomplete because ACE inhibitors do not block the non-ACE-mediated conversion of angiotensin I to A-II. Angiotensin receptor antagonists (angiotensin receptor blockers; ARBs) antagonize the action of A-II at the A-II type 1 (AT(1)) receptor, whilst allowing the potentially beneficial actions of A-II mediated via the A-II type 2 (AT(2)) receptor. Evidence that the clinical benefit demonstrated with ACE inhibitors in patients with CHF may extend to ARBs has only emerged recently. Combination therapy with both an ACE inhibitor and an ARB has a number of potential advantages and has been investigated in several large-scale clinical trials recently. In patients with CHF, first-line therapy should include an ACE inhibitor and a beta-adrenoceptor antagonist. The addition of an ARB provides symptomatic relief but has not been shown to improve survival. Where an ACE inhibitor is not tolerated, treatment with an ARB would seem an appropriate alternative. There is insufficient data to support the routine use of ARBs as first-line therapy in the management of CHF.

Angiotensin inhibition reduces glomerular damage and renal chemokine expression in MRL/lpr mice

Beneficial effects of angiotensin II inhibition during inflammatory renal disease may involve both hemodynamic and nonhemodynamic mechanisms. To analyze whether angiotensin II inhibition has protective effects on lupus-like, autoimmune-mediated renal damage in MRL/lpr mice, four groups of mice were treated orally for 6 weeks with: 1) vehicle, 2) enalapril (3.0 mg/kg per day), 3) candesartan cilexetil (5.0 mg/kg), or 4) amlodipine (10 mg/kg) as a blood pressure control (n = 9-12/group). All antihypertensive treatments lowered blood pressure to a similar level compared with vehicle group (enalapril: 99.8 +/- 8.3 mm Hg; candesartan: 101 +/- 9 mm Hg; amlodipine: 103.8 +/- 6.7 mm Hg; vehicle: 113.5 +/- 4.6 mm Hg). Vehicle-treated mice developed a moderate glomerular injury with albuminuria (35.1 +/- 39.0 microg/mg of creatinine). Glomerular lesions consisted of immune complex deposition and mesangial expansion with increased mesangial cell proliferation. Amlodipine treatment had no significant protective effects. In contrast to vehicle- and amlodipine-treated mice, those subjected to angiotensin II blockade with enalapril or candesartan had reduced albuminuria, glomerular expansion, and mesangial proliferation. This was associated with significantly reduced renal chemokine mRNA expression compared with vehicle treatment. Our results show that inhibition of angiotensin II has protective effects on the glomerular damage of MRL/lpr mice that extend beyond hemodynamics and involve down-modulation of glomerular inflammation, reduction of mesangial cell proliferation, and decrease in chemokine expression.

The pulmonary renin-angiotensin system

The circulating renin-angiotensin system (RAS) has a well-described role in circulatory homeostasis. Recently, local tissue-based RAS have also been described which appear to play a key role in the injury/repair response. The expression of RAS components and the elevation of angiotensin converting enzyme in a number of interstitial lung diseases suggests the existence of a pulmonary RAS and that angiotensin II could mediate, at least in part, the response to lung injury. Activation of a local RAS within the pulmonary circulation and lung parenchyma could influence the pathogenesis of lung injury via a number of mechanisms including an increase in vascular permeability, vascular tone and fibroblast activity, and by reducing alveolar epithelial cell survival. The ability of both ACE inhibitors and angiotensin II receptor antagonists to attenuate experimental lung injury further supports a role for RAS activation and suggests these agents may be useful in the treatment of diffuse parenchymal lung disease. However, further studies are required to delineate the cell types responsible for RAS component expression in the lung and also to identify the key effector molecules of this system. The presence of common polymorphisms in RAS genes and their study in relation to specific physiological phenotypes will aid both our understanding of the role of RAS in the lung and also aid the targeting of future therapies.

[Progression of chronic renal insufficiency and its prevention using angiotensin converting enzyme inhibitors and angiotensin antagonists]

Progression of chronic nephropathies can be significantly retarded by optimal control of blood pressure. To achieve target blood pressure combined treatment is usually necessary in patients with chronic nephropathies. Drugs interfere with the renin-angiotensin-aldosterone system (angiotensin converting enzyme inhibitors and angiotensin antagonists) have as compared with other antihypertensive agents with a comparable blood pressure control a more marked renoprotective effect and are renoprotective also in normotensive microalbuminuric patients with diabetic nephropathy and in proteinuric patients with non-diabetic nephropathies. Treatment with angiotensin converting enzyme inhibitors and angiotensin antagonists should be started as soon as possible and should be lifelong.

Mechanical stretch-induced mitogen-activated protein kinase activation is mediated via angiotensin and endothelin systems in vascular smooth muscle cells

We previously reported that pressure loading of the vascular wall can activate mitogen-activated protein kinases (MAPKs), enzymes believed to be involved in the pathway for cell proliferation, partly via the vascular angiotensin system in isolated perfused rat aorta. In this study, we examined whether cyclic stretching of vascular smooth muscle cells (VSMC) also produces activation of p42 and p44 MAPKs in cultured rat VSMC and whether stretch-induced MAPK activation is mediated via angiotensin and endothelin systems in VSMC. Cyclic stretching of VSMC produced an elongation-dependent and frequency-dependent increase in p42 and p44 MAPK activity. The stretch-induced p42 and p44 MAPK activation was inhibited by the angiotensin receptor antagonist losartan and by the angiotensin-converting enzyme inhibitor, captopril. The MAPK activation was also inhibited by the endothelin receptor antagonist cyclo(D-alpha-aspartyl-L-prolyl-D-valyl-L-leucyl-D-tryptophyl) (BQ123) and by the endothelin-converting enzyme inhibitor phosphoramidon. Replacement of medium with culture medium of stretched cells caused MAPK activation, which was inhibited by losartan and BQ123. The results of the present study suggest that cyclic stretching of VSMC can activate p42 and p44 MAPKs and that the MAPK activation is mediated via angiotensin and endothelin systems in VSMC.

125I[Sar(1)Ile(8)] angiotensin II has a different affinity for AT(1) and AT(2) receptor subtypes in ovine tissues

Iodinated angiotensin II (Ang II) and its analogues are often assumed to have equal affinities for AT(1) and AT(2) receptor subtypes. However, using saturation and competition binding assays in several tissues from pregnant, nonpregnant, and fetal sheep, we found the affinity of 125I[Sar(1)Ile(8)] Ang II for Ang II receptors was different (P<0.05) between tissue types. The dissociation constants (Kd) and half maximal displacements of [Sar(1)Ile(8)] Ang II (Sar IC(50)) were directly related (P<0.05) to proportions of AT(1) receptors, and inversely related (P<0.05) to proportions of AT(2) receptors in tissues from all groups combined, in tissues from individual groups (pregnant, nonpregnant or fetal), and in some individual tissues (uterine arteries and aortae). This suggests that 125I[Sar(1)Ile(8)] Ang II has a different affinity for AT(1) and AT(2) receptors in ovine tissues. The Kds of 125I[Sar(1)Ile(8)] Ang II for "pure" populations of AT(1) and AT(2) receptors were 1.2 and 0.3 nM, respectively, i.e. affinity was four-fold higher for AT(2) receptors. We corrected the measured proportions of the receptor subtypes using their fractional occupancies. In tissues which contained at least 10% of each receptor subtype, the corrected proportions were significantly altered (P<0.05), even in some tissues, to the extent of being reversed.

Effects of cariporide and losartan on hypertrophy, calcium transients, contractility, and gene expression in congestive heart failure

BACKGROUND

The purpose of this study was to compare long-term effects of cariporide with those of losartan in postinfarction heart failure.

METHODS AND RESULTS

Female Sprague-Dawley rats with large myocardial infarctions and sham controls were randomized to losartan, cariporide, or placebo after 7 days and treated for 49 days. Cardiac function was assessed by echocardiography and measurement of left ventricular pressures, and gene expression was assessed by competitive reverse transcription-polymerase chain reaction. Cell dimensions, shortening, and relaxation were determined by videomicroscopy and calcium transients by fura 2. Losartan reduced postinfarction systolic and diastolic left ventricular dilation (by 24% and 31%, respectively), left and right ventricular weight (by 22% and 26%, respectively), and cardiomyocyte hypertrophy length and width (by 62% and 54%, respectively). Induction of myocardial atrial natriuretic peptide decreased 66%. Cariporide did not affect postinfarction hypertrophy or atrial natriuretic peptide. Losartan and cariporide respectively improved reduced cellular contractility (55% and 30%) and reduced elevated systolic (86% and 27%) and diastolic (49% and 43%) calcium. Losartan and cariporide respectively reduced prolonged time to 50% relaxation (66% and 25%) and time to 50% calcium reduction (55% and 53%).

CONCLUSIONS

Losartan and cariporide improve cardiomyocyte contractility and calcium regulation in chronic heart failure. Losartan has salutary effects on postinfarction remodeling and gene expression, whereas cariporide is neutral.