Cardiovascular protective role of a low-dose antihypertensive combination in obese Zucker rats

Exercise Training Restores Cardiac MicroRNA-1 and MicroRNA-29c to Nonpathological Levels in Obese Rats

We previously reported that aerobic exercise training (AET) consisted of 10 weeks of 60-min swimming sessions, and 5 days/week AET counteracts CH in obesity. Here, we evaluated the role of microRNAs and their target genes that are involved in heart collagen deposition and calcium signaling, as well as the cardiac remodeling induced by AET in obese Zucker rats. Among the four experimental Zucker groups: control lean rats (LZR), control obese rats (OZR), trained lean rats (LZR + TR), and trained obese rats (OZR + TR), heart weight was greater in the OZR than in the LZR group due to increased cardiac intramuscular fat and collagen. AET seems to exert a protective role in normalizing the heart weight in the OZR + TR group. Cardiac microRNA-29c expression was decreased in OZR compared with the LZR group, paralleled by an increase in the collagen volumetric fraction (CVF). MicroRNA-1 expression was upregulated while the expression of its target gene NCX1 was decreased in OZR compared with the LZR group. Interestingly, AET restored cardiac microRNA-1 to nonpathological levels in the OZR-TR group. Our findings suggest that AET could be used as a nonpharmacological therapy for the reversal of pathological cardiac remodeling and cardiac dysfunction in obesity.

FXR activation improves myocardial fatty acid metabolism in a rodent model of obesity-driven cardiotoxicity

BACKGROUND AND AIMS

Obesity-driven lipotoxicity is a risk factors for cardiovascular disease. The Farnesoid X Receptor (FXR) is a bile acids sensor and member of the nuclear receptor superfamily. Activation of FXR lowers plasma triacylglycerols and glucose levels through a mechanism that involves both the repression of key regulatory genes in the liver and the modulation of insulin sensitivity in peripheral tissues. In the present study we have investigated whether administering obese (fa/fa) Zucker rats, a genetic model of obesity associated with dyslipidemia and insulin resistance, with an FXR ligand protects against lipid-induced cardiomyopathy.

METHODS AND RESULTS

FXR is expressed in neonatal cardiomyocytes and the treatment with FXR agonists, chenodeoxycholic acid (CDCA), and GW4064, increased the mRNA expression of FXR and its canonical target gene, the small heterodimer partner (SHP), as well as proliferator-activated receptor alpha PPARα, acyl-CoA oxidase (AOX) and pyruvate dehydrogenase kinase (PDK-4). Feeding obese fa/fa rats with CDCA, 12 weeks, reduced hyperinsulinemia and hyperlipidaemia. The histological-pathological analysis of hearts demonstrated that treatment with the FXR ligand reduced lipid heart content decreased the rate of apoptosis, fibrosis scores and restored heart insulin signalling. Chronic CDCA administration, in the heart, induced PPARα and PPARα-regulated genes involved in β-oxidation.

CONCLUSION

FXR agonism exerts beneficial effects in a genetic model of lipid-induced cardiomyopathy. The striking benefit of this therapy on cardiac function in this model warrants an effort to determine whether a counterpart of this activity translates in human settings.

Murine models for pharmacological studies of the metabolic syndrome

Metabolic syndrome has been described as the association of insulin resistance, hypertension, hyperlipidemia and obesity. Its prevalence increased dramatically, mainly in developed countries. Animal models are essential to understand the pathophysiology of this syndrome. This review presents the murine models of metabolic syndrome the most often used in pharmacological studies. The most common metabolic syndrome models exhibit a non-functional leptin pathway, or metabolic disorders induced by high fat diets. In a first part, and after a short introduction on leptin, its receptor and mechanism of action, we provide a detailed description of each model: SHROB, SHHF, JCR:LA-cp, Zucker, ZDF, Wistar Ottawa Karlsburg W, and Otsuka Long-Evans Tokushima Fatty rats, ob/ob, db/db, agouti yellow and Mc4R KO mice. The second part of this review is dedicated to metabolic syndrome models obtained by high fat feeding.

Effects of perindopril-indapamide on left ventricular diastolic function and mass in patients with type 2 diabetes: the ADVANCE Echocardiography Substudy

BACKGROUND

The Action in Diabetes and Vascular Disease (ADVANCE) Study demonstrated that a fixed combination of perindopril and indapamide reduced the risk of major vascular events and mortality in patients with type 2 diabetes. This Echocardiographic Substudy was designed to determine the effects of this treatment on left ventricular diastolic function and left ventricular mass.

METHODS

Five hundred and fifty-five patients entering ADVANCE underwent quantitative echocardiography prior to randomization and after 6 months and 4 years of treatment with perindopril-indapamide or placebo. Main end points were left ventricular diastolic function (ratio of mitral E velocity/early medial mitral annular tissue Doppler velocity, E/Em, and left atrial volume index) and left ventricular mass index.

RESULTS

Overall, blood pressure was reduced in the perindopril-indapamide group compared with placebo. E/Em and left atrial volume index both increased over the 4 years. There was no effect of perindopril-indapamide on E/Em, although there was a small attenuation of the increase in left atrial volume index with active treatment. Left ventricular mass index was reduced by 2.7 g/m with active treatment (95% confidence interval -5.0 to -0.1, P = 0.04).

CONCLUSION

Compared with placebo, the perindopril-indapamide combination reduced blood pressure and left ventricular mass in patients with diabetes, but did not improve left ventricular diastolic function. Left ventricular diastolic function worsened in both groups over 4 years, despite blood pressure reduction and reduction in left ventricular mass. Improving left ventricular diastolic function remains a challenge in patients with diabetes.

Improvement of left ventricular diastolic function induced by β-blockade: a comparison between nebivolol and metoprolol

OBJECTIVES

Enhanced adrenergic drive is involved in the development of left ventricular (LV) diastolic dysfunction observed in metabolic syndrome (MS). Thus, β-blockers might improve LV dysfunction observed in MS, but whether this occurs is unknown.

METHODS

We assessed in Zucker fa/fa rats the effects of short- (5 days) and long-term (90 days) metoprolol ('pure' β-blockade; 80 mg/kg/day) or nebivolol (β-blocker with vasodilating properties; 5mg/kg/day) treatment on LV hemodynamics and remodeling, as well as the long-term effects on coronary and peripheral endothelial dysfunction.

RESULTS

At identical degree of β(1)-receptor blockade, metoprolol and nebivolol decreased heart rate to the same extent and preserved cardiac output via increased stroke volume. None of the β-blockers, either after long- or short-term administration, modified LV end-systolic pressure-volume relation. Both β-blockers reduced, after long-term administration, LV end-diastolic pressure, Tau and end-diastolic pressure-volume relation, and this was associated with reduced LV collagen density, but not heart weight. Similar hemodynamic effects were also observed after short-term nebivolol, but not short-term metoprolol. These short-term effects of nebivolol were abolished by NO synthase inhibition. At the vascular level, nebivolol, and to a lesser extend metoprolol, improved NO dependent coronary vasorelaxation, which was abolished by NO synthase inhibition.

CONCLUSIONS

In a model of MS, the β-blockers metoprolol and nebivolol improve to the same extent LV hemodynamics, remodeling and diastolic function, but nebivolol prevent more markedly endothelium dependent vasorelaxation involving a more marked enhancement of NO bio-availability.

No altered blood pressure and serum markers of oxidative stress after a long time dietary fish oil in the genetically 9 month-old type-2 diabetes Zucker rat

In this study, we investigated the effect of a high n-3 fatty acid diet (eicosapentaenoic and docosahexaenoic acids) in Zucker obese and lean rats on blood pressure in association with physiological parameters, serum biochemistry and oxidative stress analysis. After 150 days of treatment, dietary fish oil supplementation in Zucker obese rats (9 months of age) reduces bodyweight gain and serum triglyceridemia and nitrite levels, increases serum glucose and angiotensin converting enzyme activity, but does not alter blood pressure, cholesterol levels and serum markers of oxidative stress (malondialdehyde, glutathione), compared to the Zucker rats fed control diet. According to these results, we can consider that after 150 days of treatment, fish oil is not enough to regulate parameters involved in the metabolic syndrome, such as cholesterolemia and blood pressure, in a 9 month-old genetically type-2 diabetes rat.

Cardiovascular protective effects of nebivolol in Zucker diabetic fatty rats

BACKGROUND

Although effective in reducing blood pressure, therapy with a first-generation [beta]-blocker is currently controversial in metabolic syndrome due to its negative impact on carbohydrate and lipid metabolism.

OBJECTIVE AND DESIGN

We evaluated the effects of nebivolol, a third-generation highly selective [beta]-blocker with additional vasodilating activity, versus the traditional [beta]-blocker atenolol in controlling functional and morphological cardiovascular damage in a rat model of metabolic syndrome.

METHODS

During 6 months, Zucker diabetic fatty (ZDF) rats and control lean Zucker rats (LZR) were studied. The experimental groups were: untreated ZDF, ZDF along with nebivolol, ZDF along with atenolol and LZR. Blood pressure, plasma insulin, triglycerides, cholesterol, glucose and platelet aggregation were evaluated. Malondialdehyde, reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, CuZn superoxide dismutase, catalase and glutathione peroxidase were determined in heart homogenates and transforming growth factor [beta]1 and plasminogen activator inhibitor-1 (PAI-1) expression, by immunohistochemistry (IHC). Vascular reactivity, vascular cell adhesion molecule-1, platelet endothelial cell adhesion molecule-1, PAI-1, enhanced nitric oxide synthase and collagen expression were evaluated in aorta.

RESULTS

Nebivolol and atenolol presented a similar reduction in blood pressure. However, nebivolol showed a better lipid profile, preserved left ventricular function, a significant control in left ventricular geometry and moderated left ventricular hypertrophy versus atenolol. Significant reduction in platelet aggregation and a substantial endothelium-dependent and endothelium-independent relaxation in vessels were also shown in the nebivolol group versus atenolol group. Antioxidant defenses were preserved by nebivolol with a reduction in oxidative stress parameters. Vascular cell adhesion molecule-1, platelet endothelial cell adhesion molecule-1, PAI-1 and eNOS were favorably modulated with nebivolol in vessel wall. TGF[beta]1, PAI-1 and accumulation of collagen-III and collagen-I were also diminished in heart with nebivolol.

CONCLUSION

The present study provides substantial information supporting an actual protective role of nebivolol in comparison with atenolol in experimental metabolic syndrome.

Heart and iron deficiency anaemia in rats with renal insufficiency: the role of hepcidin

AIM

Anaemia is prevalent in chronic kidney disease (CKD) and induces significant changes in heart and kidney. In this study, we evaluated the relationship between iron metabolism, hepcidin and inflammation focusing on left ventricular (LV) function, in a remnant kidney rat model.

METHODS

Rats with 5/6 subtotal nephrectomy (STNx) and sham operation. Haemoglobin (Hb), serum iron (SI), fractional shortening (FS%) by echocardiograms were evaluated. Six months after STNx, the heart and kidney were processed by immunohistochemistry with antibodies against hypoxia-inducible factors (HIF)-1alpha, erythropoietin (EPO), pro-hepcidin, caspase-3, tumour necrosis factor (TNF)-alpha and interleukin (IL)-6.

RESULTS

Hb (g/dL) STNx: 10.8 +/- 0.8, sham: 14.7 +/- 0.6 (P < 0.01); SI (microg/dL) STNx: 154.5 +/- 24.5, sham: 287.5 +/- 32.1 (P < 0.01); heart weight (g) STNx: 2.21 +/- 0.15, sham: 1.12 +/- 0.12 (P < 0.01); FS% STNx: 28.4 +/- 2.5, sham: 45.1 +/- 4.1 (P < 0.01). There was a correlation between Hb and FS% (r = 0.95; P < 0.01) and between SI and FS% (r = 0.86; P < 0.01) in the STNx group. Tissue ferritin was reduced in heart and in kidney in the STNx group (P < 0.01). HIF-1alpha was expressed in cardiomyocytes (positive cells/area) STNx: 32 +/- 5, sham: 4 +/- 1; and tubular cells in STNx group: 70 +/- 16, sham: 10 +/- 3, P < 0.01. Hepcidin (% staining/area) in heart STNx: 6.6 +/- 0.8, sham: 0.8 +/- 0.1; in kidney STNx: 9.7 +/- 2.6, sham: 3.7 +/- 0.9, P < 0.01. EPO (% staining/area) in heart STNx: 2.6 +/- 0.4, sham: 0.8 +/- 0.2; in kidney STNx: 10.2 +/- 1.4, sham: 1.2 +/- 0.6; P < 0.01. In STNx group positive caspase-3, TNF-alpha and IL-6 were detected in heart and renal cells.

CONCLUSION

Low LV performance is associated with iron deficiency anaemia in rats with CKD. Furthermore, overproduction of HIF-1alpha and the activation of caspase-3 seem to be associated with iron deficiency and with inflammatory markers. Hepcidin seems to plays a key role in this mechanism.

ACE inhibition and AT1 receptor blockade prevent fatty liver and fibrosis in obese Zucker rats

OBJECTIVE

Non-alcoholic steatohepatitis (NASH), which is a common liver disease in industrialized countries, is associated with obesity, hypertension, and type-2 diabetes (metabolic syndrome). Since angiotensin II (ANG II) has been suggested to play an important role in liver inflammation and fibrosis, the purpose of this study was to investigate whether therapy against renin-angiotensin system (RAS) may provide some beneficial effect in liver of an animal model of metabolic syndrome.

METHODS AND PROCEDURES

For 6 months, obese Zucker rats (OZRs) were treated as follows: OZR-group, OZR + Perindopril (P) group, OZR + Irbesartan (IRB) group, OZR + Amlodipine (AML) group, and lean Zucker rats (LZRs) group as a control. Livers were evaluated by immunohistochemistry techniques using corresponding antibodies.

RESULTS

All treated groups showed a similar reduction in blood pressure compared to untreated OZR. Therapy either with IRB or P improves insulin sensitivity and reduces hepatic enzyme level with respect to untreated OZR. Conversely, AML failed to modify both parameters. Untreated OZR displayed higher hepatic ANG II levels and steatosis together with a marked increase in tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and transforming growth factor-beta1 (TGF-beta1) level compared to LZR. Following RAS inhibition either by P or IRB, a significant reduction (P < 0.01) in the immunostaining of TNF-alpha, IL-6 and TGF-beta1 compared to untreated OZR was observed.

DISCUSSION

These results indicate that ANG II expression is increased in the liver of these animals with steatohepatitis. Furthermore, RAS control by either angiotensin-converting enzyme inhibition or AT1 receptor blockade seems to provide a beneficial modulation concerning the inflammatory response to liver injury in this model. Consequently, blockade of RAS could be a new approach to prevent or to treat patients with NASH.

Antiobesity effects of Isaria sinclairii by repeated oral treatment in obese Zucker rats over a 4-month period

In the present study, the antiobesity effects of Isaria sinclairii (I. sinclairii, a fungus cultured on silkworms) powder were investigated in obese (fa/fa) Zucker rats over 4 mo. Rats were given 5 or 10% (w/w) I. sinclairii powder (I. S.), 10% mulberry leaf powder, or 10% silkworm powder mixed with standard diet; a fifth (control) group was given standard diet alone. Dose-dependent decreases in rate of body weight gain were observed in the IS-treated groups after 2 wk of treatment. Interestingly, weights of abdominal adipose tissues surrounding the epididymides were markedly reduced by I. S., in parallel with an attenuated body weight gain. However, no significant differences were observed versus the control group in terms of urinalysis or ocular or histopathological examinations. In the serum, total cholesterol, triglyceride, bilirubin, and low-density lipoprotein (LDL) were significantly lower in the 10% I. S. group than control after 17 wk of treatment. The mulberry leaf diet (10%) significantly reduced serum bilirubin levels. Obese (fa/fa) Zucker rats displayed markedly elevated serum leptin levels (>24.6%) in the I. S. 5 and 10% groups compared with nontreated controls. Data suggest that I. sinclairii exerts an antiobesity effect in Zucker obese rats.

Myocardial preconditioning against ischemia-reperfusion injury is abolished in Zucker obese rats with insulin resistance

Insulin resistance (IR) precedes the onset of Type 2 diabetes, but its impact on preconditioning against myocardial ischemia-reperfusion injury is unexplored. We examined the effects of diazoxide and ischemic preconditioning (IPC; 5-min ischemia and 5-min reperfusion) on ischemia (30 min)-reperfusion (240 min) injury in young IR Zucker obese (ZO) and lean (ZL) rats. ZO hearts developed larger infarcts than ZL hearts (infarct size: 57.3 +/- 3% in ZO vs. 39.2 +/- 3.2% in ZL; P < 0.05) and also failed to respond to cardioprotection by IPC or diazoxide (47.2 +/- 4.3% and 52.5 +/- 5.8%, respectively; P = not significant). In contrast, IPC and diazoxide treatment reduced the infarct size in ZL hearts (12.7 +/- 2% and 16.3 +/- 6.7%, respectively; P < 0.05). The mitochondrial ATP-activated potassium channel (K(ATP)) antagonist 5-hydroxydecanoic acid inhibited IPC and diazoxide-induced preconditioning in ZL hearts, whereas it had no effect on ZO hearts. Diazoxide elicited reduced depolarization of isolated mitochondria from ZO hearts compared with ZL (73 +/- 9% in ZL vs. 39 +/- 9% in ZO; P < 0.05). Diazoxide also failed to enhance superoxide generation in isolated mitochondria from ZO compared with ZL hearts. Electron micrographs of ZO hearts revealed a decreased number of mitochondria accompanied by swelling, disorganized cristae, and vacuolation. Immunoblots of mitochondrial protein showed a modest increase in manganese superoxide dismutase in ZO hearts. Thus obesity accompanied by IR is associated with the inability to precondition against ischemic cardiac injury, which is mediated by enhanced mitochondrial oxidative stress and impaired activation of mitochondrial K(ATP).

Angiotensin-converting enzyme inhibition reduces lipid deposits in myocardium and improves left ventricular function of obese zucker rats

OBJECTIVE

Alterations in the renin angiotensin system, cardiac lipotoxicity, and left ventricular (LV) dysfunction have been reported in obese rats. The present study examined whether angiotensin-converting enzyme inhibition could ameliorate lipid deposition and ventricular function in the myocardium of obese Zucker rats (OZRs).

RESEARCH METHODS AND PROCEDURES

For 6 months, rats were treated as follows: Group (G) 1, OZR, no treatment; G2, OZR + ramipril (R); G3, OZR + amlodipine (AML); and G4, lean Zucker rats. LV function was assessed by echocardiogram and lipid deposits in cardiomyocytes (LDCM) by light microscopy using Oil red O.

RESULTS

At the end of the experiment, both OZR + R and OZR + AML groups presented similar reduction in blood pressure in comparison with untreated OZR (p < 0.01). OZR with R presented lower insulin-to-glucose ratio and lower serum triglycerides and cholesterol when compared with both untreated OZR and OZR with AML (p < 0.01). Fractional shortening by echocardiogram was as follows: G1, 25.4 +/- 3.8 (vs. G2 and G4, p < 0.05); G2, 37.2 +/- 2.4; G3, 29.3 +/- 4.4 (vs. G2 and G4, p < 0.05); and G4, 40.8 +/- 2.3. Percentage LDCM was as follows: G1, 12.4 +/- 2.7 (vs. G2 and G4, p < 0.05); G2, 0.8 +/- 0.2; G3, 11.1 +/- 2.1 (vs. G2 and G4, p < 0.05); and G4, 0.1 +/- 0.1. There was a negative correlation between fractional shortening and LDCM percentage in OZR (r = -0.93) and in OZR + AML (r = -0.87).

DISCUSSION

AML reduced blood pressure significantly; however, it failed to modify both metabolic parameters and LDCM. In contrast, R showed a substantial reduction in LDCM, together with LV function preservation.

Losartan and acute myocardial infarction in insulin-resistant Zucker fatty rats: reduced ventricular arrhythmias and improved survival

Insulin resistance (IR) and diabetes increase the risk of acute myocardial infarction (MI). Angiotensin receptor blockers (ARBs) have been shown to reduce the risk of cardiovascular events in patients with hypertension and diabetes, and to be beneficial after a large MI. Whether pretreatment with ARBs is beneficial in acute MI is unknown. We evaluated whether pre-, peri-, and post-MI treatment with the ARB losartan improved the outcome in the IR Zucker fatty rat (ZFR). ZFR (n=264) received either losartan (3 mg/kg daily) or vehicle for 7 d prior to MI. Early (24 h) protocol (n=31): ventricular arrhythmias were evaluated post-MI using continuous ambulatory ECG monitoring. Late (38 d) protocol (n=233): losartan was increased to 10 mg/kg daily 10 d post-MI and to 30 mg/kg daily 20 d post-MI. Blood glucose, cardiac hemodynamics and remodeling, GLUT-4, fetal gene expression, and survival were evaluated. In large-MI rats, losartan improved early survival (43% vs. 27% in controls, p=0.01) and late survival (23% vs.15% in controls, p=0.02). Improved early survival was associated with a reduction in ventricular arrhythmias. Losartan reduced pulmonary congestion, cardiac hypertrophy, and fetal gene expression in the absence of statistically significant changes in ventricular dilatation and hemodynamics. Blood glucose and cardiac GLUT-4 expression did not change with losartan. In IR ZFR, losartan improves post-MI survival, likely as a result of an early reduction in ventricular arrhythmias. There was also an associated reduction in pulmonary congestion, hypertrophy, and fetal gene expression.

Regulation of vascular endothelial growth factor expression and vascularization in the myocardium by insulin receptor and PI3K/Akt pathways in insulin resistance and ischemia

OBJECTIVE

This study characterized the role of insulin receptors and resistance on vascular endothelial growth factor (VEGF) expression and myocardial vascularization in physiological conditions and after ischemia.

METHODS AND RESULTS

Cardiac microvascular density was reduced by 30% in insulin-resistant Zucker fatty rats versus lean controls. This was associated with a parallel 40% inhibition of insulin-stimulated activation of both Akt and VEGF expression in the myocardium and cardiomyocytes. In contrast, the activation of Erk1/2 by insulin remained unchanged. In cultured cardiomyocytes, insulin or insulin-like growth factor (IGF)-1 increased VEGF mRNA and protein expression by 2-fold. Inhibition of PI3K/Akt, especially Akt2-mediated cascades but not the Ras/MEK/Erk pathway, using chemical inhibitors, dominant negative adenoviral constructs, or siRNA approaches suppressed VEGF mRNA expression by insulin. Ventricular tissues from muscle insulin receptor knockout (MIRKO) mice, which lack insulin receptors in the myocardium, have significant reductions in insulin but not IGF-1 signaling, VEGF expression, and vascular density before and after ischemia versus controls.

CONCLUSIONS

Insulin regulates VEGF gene expression and vascularization in the myocardium specifically via insulin receptors and the activation of PI3K/Akt pathway. Selective inhibition of this pathway may lead to the decreases in VEGF expression and capillary density in the myocardium of patients with insulin resistance.

Histochemical characteristics of soleus muscle in angiotensin-converting enzyme gene knockout mice

We examined the histochemical characteristics of soleus muscle in the angiotensin-converting enzyme (ACE) gene (Ace in mice, ACE in humans) knockout mice. Serial sections of soleus muscle of wild-type (Ace+/+, n=20) and heterozygous mutant (Ace+/-, n=24) mice were stained for myosin adenosine triphosphatase activity to identify different muscle fiber types. Capillaries were visualized by amylase-periodic acid-Schiff staining. ACE activity in the serum and gastrocnemius muscle was higher in male mice than in female mice. Female and male Ace+/- mice had markedly lower ACE activity in the serum and the gastrocnemius muscle than did female and male Ace+/+ mice, respectively. In both male and female mice, the composition of fiber types (type I and IIa) did not differ significantly between Ace+/+ and Ace+/- mice. There was no significant gender difference in capillary density. Ace+/- mice had significantly more capillaries around type IIa fibers (5.44 +/- 0.18 vs. 5.01 +/- 0.13, p<0.05) than Ace+/+ mice. The differences in the number of capillaries around type I fibers and in the number of capillaries around per fiber (capillary:fiber ratio) between Ace+/- and Ace+/+ mice were not significant (p<0.1). There was no significant difference in the mean cross-sectional area occupied by one capillary and the number of capillaries per fiber area between Ace+/+ and Ace+/- mice. In conclusion, knockout of the Ace gene in mice increased capillary density, as expressed by the mean number of capillaries around type IIa fibers. This finding suggests a possible mechanism for the cardioprotective effects of ACE inhibitors.

Perindopril/indapamide combination more effective than enalapril in reducing blood pressure and left ventricular mass: the PICXEL study

OBJECTIVE

Few data are available comparing the effects of monotherapy and combination therapy on target organ damage. The PICXEL study compared the efficacy of a strategy based on first-line combination with perindopril/indapamide versus monotherapy with enalapril in reducing left ventricular hypertrophy (LVH) in hypertensive patients.

METHODS

In this 1-year multicentre randomized double-blind study, patients received an increasing dosage of perindopril/indapamide (n = 284) or enalapril (n = 272). Changes in blood pressure and echocardiographic measures of LVH were assessed from baseline to the end of treatment. Reading of the echocardiograms was central and blinded for therapy, patient and sequence.

RESULTS

Systolic and diastolic blood pressure decreased significantly more in the perindopril/indapamide than in the enalapril group (P < 0.0001 and P = 0.003). The left ventricular mass index decreased by 13.6 +/- 23.9 g/m(2) (mean +/- SD) with perindopril/indapamide (P < 0.0001) and 3.9 +/- 23.9 g/m(2) with enalapril (P < 0.005); these decreases were significantly different (P < 0.0001). The left ventricular internal diameter, posterior and interventricular septal wall thickness decreased significantly with perindopril/indapamide (P < or = 0.0001); the interventricular septal wall thickness decreased significantly with enalapril (P < 0.001). Both treatments were well tolerated.

CONCLUSION

A strategy based on first-line combination with perindopril/indapamide achieved better blood pressure decrease with a significantly greater degree of LVH reduction than a strategy based on monotherapy with enalapril in hypertensive patients with LVH.

The effect of non-insulin dependent diabetes mellitus on uncontrolled hemorrhage in a rodent model

OBJECTIVE

Diabetes mellitus (DM) is an independent risk factor for higher morbidity and mortality rates from trauma. We tested the null hypothesis that there would be no difference in the hemorrhage volumes and hemodynamic responses to uncontrolled hemorrhage between Zucker Diabetic Fat rats (ZDF) and euglycemic Sprague-Dawley rats (SD).

METHODS

Twenty-four adult male rats (12 ZDF and 12 SD) were anesthetized with althesin via the intraperitoneal route. The femoral artery was cannulated by cut-down to monitor the heart rate (HR), mean arterial pressure (MAP) and to obtain blood samples for blood gas analysis. Twelve rats (6 ZDF and 6 SD) underwent uncontrolled hemorrhage by 50% tail amputation. Twelve rats (6 ZDF and 6 SD) served as non-hemorrhage controls. The HR, MAP, lactate (LAC), glucose levels (GL) and cumulative hemorrhage volume (CHV) were measured pre-hemorrhage and then every 15 min post-hemorrhage for 120 min. Data were reported as mean+/-S.E.M. Group comparisons were analyzed by ANOVA with repeated values; post hoc testing by Bonferroni (all tests were two-tailed, alpha = 0.05).

RESULTS

Pre-hemorrhage the SD and ZDF were evenly matched for LAC, HR and MAP. CHV (cm3/100 g) was significantly (p = 0.008) greater in the ZDF (1.49+/-0.12) as compared to the SD (0.38+/-0.11). The ZDF had significantly (p < 0.001) higher LAC (7.96+/-0.61 mmol/L) than the SD (2.0+/-0.41 mmol/L).

CONCLUSION

DM as compared to non-DM rats suffered a greater blood loss with a more severe lactic acidosis after a comparable uncontrolled vascular injury.

Caloric intake and hypothalamic neurotransmitters in Zucker rats made acutely diabetic with streptozocin

Zucker rats, lean and obese, treated with low dose intraperitoneal injections of streptozocin become hyperglycemic within 24h. Insulin levels fall, although the obese animal remains hyperinsulinemic. Associated with these changes in glucose and insulin there are transient decreases in caloric intake. Macronutrient selection studies show that protein consumption decreases. There is a trend for fat intake to decrease. The levels of hypothalamic neurotransmitters in the lean animals are not altered by streptozocin. The levels of 5-hydroxyindoleacetic acid increases in the streptozocin-treated obese animal in the paraventricular region, ventromedial region and the raphe. Serotonin is also significantly increased in the paraventricular region of the obese rat. These results suggest that acutely, treatment with streptozocin injures pancreatic islets, causing, in turn, decreases in insulin levels so that hyperglycemia ensues in both phenotypes. Associated with these perturbations are decreases in caloric intake. The magnitude of change in insulin levels is much greater in the obese rat. It is hypothesized that in the obese Zucker rat decrements in food intake are mediated by increase in serotonin turnover in the hypothalamus and these changes are related to changes of insulin levels. These data support the concept that circulating insulin affects hypothalamic neurotransmitters.

Reduced cardiac expression of plasminogen activator inhibitor 1 and transforming growth factor beta1 in obese Zucker rats by perindopril

OBJECTIVE

To determine whether angiotensin converting enzyme inhibition by perindopril can reduce cardiac transforming growth factor beta1 (TGFbeta1) and plasminogen activator inhibitor 1 (PAI-1) and therefore control collagen accumulation in an animal model with the metabolic syndrome such as the obese Zucker rat (OZR).

ANIMALS

Male OZR (group 1, n = 10); OZR treated with perindopril (group 2, n = 10); and lean Zucker rats (group 3, n = 10).

METHODS

During six months, group 2 received 3 mg/kg/day of perindopril orally and group 1 and group 3 were given a vehicle. Hearts were processed for pathology studies including immunohistochemical analysis with antibodies to PAI-1, TGFbeta1, collagen type I, and collagen type III.

RESULTS

Group 2 had lower blood pressure (126.7 (2) v 148.6 (2.7) mm Hg, p < 0.01) than untreated OZR and had decreased cardiac PAI-1 (3.6 (0.4) v 13.5 (1.7)% of positive area/field, p < 0.01), TGFbeta1 in myocytes (0.13 (0.1) v 9.14 (4.7)%/area, p < 0.01) and in interstitium (19.8 (6.8) v 178.9 (27.4) positive cells/area, p < 0.01), collagen I (3 (0.8) v 13.3 (1)%/area, p < 0.01), collagen III (5 (0.6) v 9.5 (0.9)%/area, p < 0.01), and collagen I to collagen III ratio (0.59 (0.13) v 1.40 (0.15) p < 0.01) compared with untreated OZR.

CONCLUSION

These results suggest that perindopril reduces cardiac PAI-1 and TGFbeta1 and ameliorates cardiac fibrosis in a rat model with multiple cardiovascular risk factors.

Long-term protection of obese Zucker rat kidneys from fibrosis and renal failure with an angiotensin-converting enzyme inhibitor/diuretic combination

Some combinations of antihypertensive agents were shown to reduce proteinuria in patients with renal failure. However, preventive effects of such combinations on renal structure and function are presently unknown when treatment is administered before the onset of renal abnormalities. We thus investigated the long-term effects of an angiotensin-converting enzyme (ACE) inhibitor (perindopril)/diuretic (indapamide) combination (per/ind) in the Zucker rat, a classical model of chronic renal failure associated with obesity, hyperlipidemia, and insulin resistance. Two-month-old lean and obese Zucker rats, presenting normal renal structure and function at this young age, received per/ind (0.76 + 0.24 mg/kg of body weight/day) or the vehicle of this combination by daily gavage. After 8.5 consecutive months of treatment, those 10.5-month-old rats were used for determination of renal structural and functional parameters which were examined using standard renal clearance experiments and kidney tissue analysis. Per/ind prevented focal and segmental glomerular hyalinosis and tubulo-interstitial damage in obese rats. Treatment was also associated with a significant reduction in several staining markers of glomerular and interstitial fibrosis. The hypertrophy of superficial glomeruli and the mesangial expansion of deep glomeruli observed in control rats were reduced in per/ind-treated obese rats. The severe proteinuria observed in 10.5-month-old control obese rats was prevented by per/ind, while glomerular filtration and renal hemodynamic parameters reached similar values to those obtained in lean animals. These results show that long-term treatment with this ACE inhibitor/diuretic combination protects renal structure and function in the obese Zucker rat, emphasizing the potential efficiency of such therapy in renal failure prevention.