Hepatoprotective and cardioprotective effects of empagliflozin in spontaneously hypertensive rats fed a high-fat diet

A combination of liver and heart dysfunction worsens the prognosis of human survival. The aim of this study was to investigate whether empagliflozin (a sodium-glucose transporter-2 inhibitor) has beneficial effects not only on cardiac and renal function but also on hepatic function. Adult (6-month-old) male spontaneously hypertensive rats (SHR) were fed a high-fat diet (60% fat) for four months to induce hepatic steatosis and mild heart failure. For the last two months, the rats were treated with empagliflozin (empa, 10 mg.kg-1.day-1 in the drinking water). Renal function and oral glucose tolerance test were analyzed in control (n=8), high-fat diet (SHR+HF, n=10), and empagliflozin-treated (SHR+HF+empa, n=9) SHR throughout the study. Metabolic parameters and echocardiography were evaluated at the end of the experiment. High-fat diet feeding increased body weight and visceral adiposity, liver triglyceride and cholesterol concentrations, and worsened glucose tolerance. Although the high-fat diet did not affect renal function, it significantly worsened cardiac function in a subset of SHR rats. Empagliflozin reduced body weight gain but not visceral fat deposition. It also improved glucose sensitivity and several metabolic parameters (plasma insulin, uric acid, and HDL cholesterol). In the liver, empagliflozin reduced ectopic lipid accumulation, lipoperoxidation, inflammation and pro-inflammatory HETEs, while increasing anti-inflammatory EETs. In addition, empagliflozin improved cardiac function (systolic, diastolic and pumping) independent of blood pressure. The results of our study suggest that hepatoprotection plays a decisive role in the beneficial effects of empagliflozin in preventing the progression of cardiac dysfunction induced by high-fat diet feeding.

Renal denervation improves cardiac function independently of afterload and restores myocardial norepinephrine levels in a rodent heart failure model

Renal nerves play a critical role in cardiorenal interactions. Renal denervation (RDN) improved survival in some experimental heart failure (HF) models. It is not known whether these favorable effects are indirect, explainable by a decrease in vascular afterload, or diminished neurohumoral response in the kidneys, or whether RDN procedure per se has direct myocardial effects in the failing heart. To elucidate mechanisms how RDN affects failing heart, we studied load-independent indexes of ventricular function, gene markers of myocardial remodeling, and cardiac sympathetic signaling in HF, induced by chronic volume overload (aorto-caval fistula, ACF) of Ren2 transgenic rats. Volume overload by ACF led to left ventricular (LV) hypertrophy and dysfunction, myocardial remodeling (upregulated Nppa, MYH 7/6 genes), increased renal and circulating norepinephrine (NE), reduced myocardial NE content, increased monoaminoxidase A (MAO-A), ROS production and decreased tyrosine hydroxylase (+) nerve staining. RDN in HF animals decreased congestion in the lungs and the liver, improved load-independent cardiac function (Ees, PRSW, Ees/Ea ratio), without affecting arterial elastance or LV pressure, reduced adverse myocardial remodeling (Myh 7/6, collagen I/III ratio), decreased myocardial MAO-A and inhibited renal neprilysin activity. RDN increased myocardial expression of acetylcholinesterase (Ache) and muscarinic receptors (Chrm2), decreased circulating and renal NE, but increased myocardial NE content, restoring so autonomic control of the heart. These changes likely explain improvements in survival after RDN in this model. The results suggest that RDN has remote, load-independent and favorable intrinsic myocardial effects in the failing heart. RDN therefore could be a useful therapeutic strategy in HF.

The treatment with sGC stimulator improves survival of hypertensive rats in response to volume-overload induced by aorto-caval fistula

Heart failure (HF) has been declared as global pandemic and current therapies are still ineffective, especially in patients that develop concurrent cardio-renal syndrome. Considerable attention has been focused on the nitric oxide (NO)/soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP) pathway. In the current study, we aimed to investigate the effectiveness of sGC stimulator (BAY41-8543) with the same mode of action as vericiguat, for the treatment of heart failure (HF) with cardio-renal syndrome. As a model, we chose heterozygous Ren-2 transgenic rats (TGR), with high-output heart failure, induced by aorto-caval fistula (ACF). The rats were subjected into three experimental protocols to evaluate short-term effects of the treatment, impact on blood pressure, and finally the long-term survival lasting 210 days. As control groups, we used hypertensive sham TGR and normotensive sham HanSD rats. We have shown that the sGC stimulator effectively increased the survival of rats with HF in comparison to untreated animals. After 60 days of sGC stimulator treatment, the survival was still 50% compared to 8% in the untreated rats. One-week treatment with sGC stimulator increased the excretion of cGMP in ACF TGR (109 ± 28 nnmol/12 h), but the ACE inhibitor decreased it (-63 ± 21 nnmol/12 h). Moreover, sGC stimulator caused a decrease in SBP, but this effect was only temporary (day 0: 117 ± 3; day 2: 108 ± 1; day 14: 124 ± 2 mmHg). These results support the concept that sGC stimulators might represent a valuable class of drugs to battle heart failure especially with cardio-renal syndrome, but further studies are necessary.

Antihypertensive and metabolic effects of empagliflozin in Ren-2 transgenic rats, an experimental non-diabetic model of hypertension

The new antidiabetic drugs, gliflozins, inhibit sodium-glucose transporter-2 in renal proximal tubules promoting glucose and sodium excretion. This leads not only to a significant improvement of glucose control but also to the reduction of blood pressure and body weight in both diabetic patients and experimental models. We examined whether these beneficial effects can also be achieved in a non-diabetic hypertensive model, namely in Ren-2 transgenic rats (TGR). Adult 6-month-old hypertensive TGR and their normotensive controls (Hannover Sprague-Dawley rats), were either untreated or treated with empagliflozin (10 mg/kg/day) for two months. Telemetric blood pressure monitoring, renal parameters as well as cardiac function via echocardiography were analyzed during the experiment. At the end of the study, the contribution of major vasoactive systems to blood pressure maintenance was studied. Metabolic parameters and markers of oxidative stress and inflammation were also analyzed. Empagliflozin had no effect on plasma glucose level but partially reduced blood pressure in TGR. Although food consumption was substantially higher in empagliflozin-treated TGR compared to the untreated animals, their body weight and the amount of epididymal and perirenal fat was decreased. Empagliflozin had no effect on proteinuria, but it decreased plasma urea, attenuated renal oxidative stress and temporarily increased urinary urea excretion. Several metabolic (hepatic triglycerides, non-esterified fatty acids, insulin) and inflammatory (TNF-α, leptin) parameters were also improved by empagliflozin treatment. By contrast, echocardiography did not reveal any effect of empagliflozin on cardiac function. In conclusion, empagliflozin exerted beneficial antihypertensive, anti-inflammatory and metabolic effects also in a non-diabetic hypertensive model.

Renal Sympathetic Denervation Attenuates Congestive Heart Failure in Angiotensin II-Dependent Hypertension: Studies with Ren-2 Transgenic Hypertensive Rats with Aortocaval Fistula

OBJECTIVE

We examined if renal denervation (RDN) attenuates the progression of aortocaval fistula (ACF)-induced heart failure or improves renal hemodynamics in Ren-2 transgenic rats (TGR), a model of angiotensin II (ANG II)-dependent hypertension.

METHODS

Bilateral RDN was performed 1 week after creation of ACF. The animals studied were ACF TGR and sham-operated controls, and both groups were subjected to RDN or sham denervation. In separate groups, renal artery blood flow (RBF) responses were determined to intrarenal ANG II (2 and 8 ng), norepinephrine (NE) (20 and 40 ng) and acetylcholine (Ach) (10 and 40 ng) 3 weeks after ACF creation.

RESULTS

In nondenervated ACF TGR, the final survival rate was 10 versus 50% in RDN rats. RBF was significantly lower in ACF TGR than in sham-operated TGR (6.2 ± 0.3 vs. 9.7 ± 0.5 mL min-1 g-1, p < 0.05), the levels unaffected by RDN. Both doses of ANG II decreased RBF more in ACF TGR than in sham-operated TGR (-19 ± 3 vs. -9 ± 2% and -47 ± 3 vs. -22 ± 2%, p < 0.05 in both cases). RDN did not alter RBF responses to the lower dose, but increased it to the higher dose of ANG II in sham-operated as well as in ACF TGR. NE comparably decreased RBF in ACF TGR and sham-operated TGR, and RDN increased RBF responsiveness. Intrarenal Ach increased RBF significantly more in ACF TGR than in sham-operated TGR (29 ± 3 vs. 17 ± 3%, p < 0.05), the changes unaffected by RDN. ACF creation induced marked bilateral cardiac hypertrophy and lung congestion, both attenuated by RDN. In sham-operated but not in ACF TGR, RDN significantly decreased mean arterial pressure.

CONCLUSION

The results show that RDN significantly improved survival rate in ACF TGR; however, this beneficial effect was not associated with improvement of reduced RBF or with attenuation of exaggerated renal vascular responsiveness to ANG II.

Sex-linked differences in the course of thioacetamide-induced acute liver failure in Lewis rats

Acute liver failure (ALF) is a clinical syndrome with high mortality rate, resulting from widespread hepatocyte damage. Its pathophysiological background is still poorly understood and preclinical studies evaluating pathophysiology and new potential therapeutic measures are needed. The model of ALF induced by administration of thioacetamide (TAA) in Lewis rats is recommended as optimal; however, the limitation of previous studies was that they were performed predominantly in male rats. In view of the growing recognition that sex as a biological variable should be taken into consideration in preclinical research, we examined its role in the development of TAA-induced ALF in Lewis rats. We found that, first, intact male Lewis rats showed lower survival rate than their female counterparts, due to augmented liver injury documented by higher plasma ammonia, and bilirubin levels and alanine aminotransferase activity. Second, in female rats castration did not alter the course of TAA-induced ALF whereas in the male gonadectomy improved the survival rate and attenuated liver injury, reducing it to levels observed in their female counterparts. In conclusion, we found that Lewis rats show a remarkable sexual dimorphism with respect to TAA-induced ALF, and male rats display dramatically poorer prognosis as compared with the females. We showed that testosterone is responsible for the deterioration of the course of TAA-induced ALF in male rats. In most general terms, our findings indicate that in the preclinical studies of the pathophysiology and treatment of ALF (at least of the TAA-induced form) the sex-linked differences should be seriously considered.

Pharmacological stimulation of Wnt/beta-catenin signaling pathway attenuates the course of thioacetamide-induced acute liver failure

Acute liver failure (ALF) is known for extremely high mortality rate, the result of widespread damage of hepatocytes. Orthotopic liver transplantation is the only effective therapy but its application is limited by the scarcity of donor organs. Given the importance in the liver biology of Wnt/beta-catenin signaling pathway, we hypothesized that its stimulation could enhance hepatocyte regeneration and attenuate the course of thioacetamide (TAA)-induced ALF in Lewis rats. Chronic treatment with Wnt agonist was started either immediately after hepatotoxic insult ("early treatment") or when signs of ALF had developed ("late treatment"). Only 23 % of untreated Lewis rats survived till the end of experiment. They showed marked increases in plasma alanine aminotransferase (ALT) activity and bilirubin and ammonia (NH3) levels; plasma albumin decreased significantly. "Early" and "late" Wnt agonist treatment raised the final survival rate to 69 % and 63 %, respectively, and normalized ALT, NH3, bilirubin and albumin levels. In conclusion, the results show that treatment with Wnt agonist attenuates the course of TAA-induced ALF in Lewis rats, both with treatment initiated immediately after hepatotoxic insult and in the phase when ALF has already developed. Thus, the pharmacological stimulation of Wnt/beta-catenin signaling pathway can present a new approach to ALF treatment.

Addition of Endothelin A-Receptor Blockade Spoils the Beneficial Effect of Combined Renin-Angiotensin and Soluble Epoxide Hydrolase Inhibition: Studies on the Course of Chronic Kidney Disease in 5/6 Nephrectomized Ren-2 Transgenic Hypertensive Rats

Introduction: Previous studies in Ren-2 transgenic hypertensive rats (TGR) after 5/6 renal ablation (5/6 NX) have shown that besides pharmacological blockade of the renin-angiotensin system (RAS) also increasing kidney tissue epoxyeicosatrienoic acids (EET) levels by blocking soluble epoxide hydrolase (sEH), an enzyme responsible for degradation of EETs, and endothelin type A (ETA) receptor blockade retards chronic kidney disease (CKD) progression. This prompted us to evaluate if this progression will be alleviated by the addition of sEH inhibitor and ETA receptor antagonist to the standard complex blockade of RAS (angiotensin-converting enzyme inhibitor plus angiotensin II type 1 receptor blocker) in rats with established CKD. Methods: The treatment regimens were initiated 6 weeks after 5/6 NX in TGR, and the follow-up period was 60 weeks. Results: The addition of sEH inhibition to RAS blockade improved survival rate, further reduced albuminuria and renal glomerular and kidney tubulointerstitial injury, and attenuated the decline in creatinine clearance – all this as compared with 5/6 NX TGR treated with RAS blockade alone. Addition of ETA receptor antagonist to the combined RAS and sEH blockade not only offered no additional renoprotection but, surprisingly, also abolished the beneficial effects of adding sEH inhibitor to the RAS blockade. Conclusion: These data indicate that pharmacological strategies that combine the blockade of RAS and sEH could be a novel tool to combat the progression of CKD. Any attempts to further extend this therapeutic regimen should be made with extreme caution.

Is renal ß-adrenergic-WNK4-NCC pathway important in salt hypertension of Dahl rats?

In 2011 Fujita and coworkers proposed that ß-adrenergic stimulation causes decreased serine/threonine-protein kinase WNK4 transcription leading to the activation of Na-Cl cotransporter (NCC) which participates in salt sensitivity and salt hypertension development in rodents. The aim of our study was to investigate whether the above hypothesis is also valid for salt hypertension of Dahl rats, which are characterized by high sympathetic tone and abnormal renal sodium handling. Male 8-week-old salt-sensitive (SS/Jr) and salt-resistant (SR/Jr) Dahl rats were fed either low-salt diet (LS, 0.4 % NaCl) or high-salt diet (HS, 4 % NaCl) for 6 weeks. Half of the animals on either diet were chronically treated with non-selective ß-blocker propranolol (100 mg/kg/day). At the end of the experiment diuresis and sodium excretion were measured prior and after hydrochlorothiazide injection (HCTZ, 10 mg/kg i.p.). Furthermore, blood pressure (BP), heart rate (HR), sympathetic (pentolinium 5 mg/kg i.v.) and NO-dependent (L-NAME 30 mg/kg i.v.) BP components were determined. Chronic HS diet feeding increased BP through sympathoexcitation in SS/Jr but not in SR/Jr rats. Concomitant propranolol treatment did not lower BP in either experimental group. Under the conditions of low salt intake HCTZ increased diuresis, natriuresis and fractional sodium excretion in SR/Jr but not in SS/Jr rats. HS diet feeding attenuated renal response to HCT in SR/Jr rats, whereas no HCTZ effect was observed in SS/Jr rats fed HS diet. Propranolol treatment did not modify diuresis or natriuresis in any experimental group. In conclusions, our present data do not support the idea on the essential importance of renal ß-adrenergic-WNK4-NCC pathway in pathogenesis and/or maintenance of salt hypertension in Dahl rats.

Renoprotection Provided by Additional Diuretic Treatment in Partially Nephrectomized Ren-2 Transgenic Rats Subjected to the Combined RAS and ETA Blockade

Objective

Our previous study in heterozygous Ren-2 transgenic rats (TGR) demonstrated that long-term treatment with endothelin receptor A (ET_A) blocker atrasentan added to the renin-angiotensin system (RAS) blockade had renoprotective effects in a model of chronic kidney disease (CKD) induced by partial nephrectomy. Since ET_A blockade is known to cause edema, we were interested whether diuretic treatment added to this therapy would be beneficial.

Design and Methods

Partial nephrectomy (NX) was performed at the age of 3 months in TGR rats which were subjected to: (i) RAS blockade alone (angiotensin receptor blocker losartan and angiotensin converting enzyme inhibitor trandolapril), (ii) combined RAS (losartan and trandolapril) and ET_A receptor blockade (atrasentan), or (iii) diuretic (hydrochlorothiazide) added to the combined RAS + ET_A blockade for 50 weeks following NX.

Results

At the end of the study systolic blood pressure and cardiac hypertrophy were similarly decreased in all treated groups. Survival was significantly improved by ET_A receptor blockade added to RAS blockade with no further effects of diuretic treatment. However, additional diuretic treatment combined with RAS + ET_A blockade decreased body weight and had beneficial renoprotective effects - reductions of both kidney weight and kidney damage markers. Proteinuria gradually increased in rats treated with RAS blockade alone, while it was substantially lowered by additional ET_A blockade. In rats treated with additional diuretic, proteinuria was progressively reduced throughout the experiment.

Conclusion

A diuretic added to the combined RAS and ET_A blockade has late renoprotective effects in CKD induced by partial nephrectomy in Ren-2 transgenic rats. The diuretic improved: renal function (evaluated as proteinuria and creatinine clearance), renal morphology (kidney mass, glomerular volume), and histological markers of kidney damage (glomerulosclerosis index, tubulointerstitial injury).

Effects of increased myocardial tissue concentration of myristic, palmitic and palmitoleic acids on the course of cardiac atrophy of the failing heart unloaded by heterotopic transplantation

The present experiments were performed to evaluate if increased heart tissue concentration of fatty acids, specifically myristic, palmitic and palmitoleic acids that are believed to promote physiological heart growth, can attenuate the progression of unloading-induced cardiac atrophy in rats with healthy and failing hearts. Heterotopic abdominal heart transplantation (HT(x)) was used as a model for heart unloading. Cardiac atrophy was assessed from the ratio of the native- to-transplanted heart weight (HW). The degree of cardiac atrophy after HT(x) was determined on days 7, 14, 21 and 28 after HT(x) in recipients of either healthy or failing hearts. HT(x) of healthy hearts resulted in 23+/-3, 46+/-3, 48+/-4 and 46+/-4 % HW loss at the four time-points. HT(x) of the failing heart resulted in even greater HW losses, of 46+/-4, 58+/-3, 66+/-2 and 68+/-4 %, respectively (P<0.05). Activation of "fetal gene cardiac program" (e.g. beta myosin heavy chain gene expression) and "genes reflecting cardiac remodeling" (e.g. atrial natriuretic peptide gene expression) after HT(x) was greater in failing than in healthy hearts (P<0.05 each time). Exposure to isocaloric high sugar diet caused significant increases in fatty acid concentrations in healthy and in failing hearts. However, these increases were not associated with any change in the course of cardiac atrophy, similarly in healthy and post-HT(x) failing hearts. We conclude that increasing heart tissue concentrations of the fatty acids allegedly involved in heart growth does not attenuate the unloading-induced cardiac atrophy.

Combined suppression of the intrarenal and circulating vasoconstrictor renin-ACE-ANG II axis and augmentation of the vasodilator ACE2-ANG 1-7-Mas axis attenuates the systemic hypertension in Ren-2 transgenic rats exposed to chronic hypoxia

The aim of the present study was to test the hypothesis that chronic hypoxia would aggravate hypertension in Ren-2 transgenic rats (TGR), a well-defined monogenetic model of hypertension with increased activity of endogenous renin-angiotensin system (RAS). Systolic blood pressure (SBP) in conscious rats and mean arterial pressure (MAP) in anesthetized TGR and normotensive Hannover Sprague-Dawley (HanSD) rats were determined under normoxia that was either continuous or interrupted by two weeks´ hypoxia. Expression, activities and concentrations of individual components of RAS were studied in plasma and kidney of TGR and HanSD rats under normoxic conditions and after exposure to chronic hypoxia. In HanSD rats two weeks´ exposure to chronic hypoxia did not alter SBP and MAP. Surprisingly, in TGR it decreased markedly SBP and MAP; this was associated with substantial reduction in plasma and kidney renin activities and also of angiotensin II (ANG II) levels, without altering angiotensin-converting enzyme (ACE) activities. Simultaneously, in TGR the exposure to hypoxia increased kidney ACE type 2 (ACE2) activity and angiotensin 1-7 (ANG 1-7) concentrations as compared with TGR under continuous normoxia. Based on these results, we propose that suppression of the hypertensiogenic ACE-ANG II axis in the circulation and kidney tissue, combined with augmentation of the intrarenal vasodilator ACE2-ANG 1-7 axis, is the main mechanism responsible for the blood pressure-lowering effects of chronic hypoxia in TGR.

Renal mechanisms contributing to the antihypertensive action of soluble epoxide hydrolase inhibition in Ren-2 transgenic rats with inducible hypertension

In the present study, we examined the effects of soluble epoxide hydrolase (sEH) inhibition on the development of angiotensin II-dependent hypertension and on renal function in transgenic rats with inducible expression of the mouse renin gene (strain name Cyp1a1-Ren-2). Hypertension was induced in these rats by indole-3-carbinol (I3C; 0.3% in the diet) for 12 days. The sEH inhibitor cis-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (c-AUCB) was given in two doses (13 or 26 mg l-1) in drinking water. Blood pressure (BP), body weight (BW) and renal excretory parameters were monitored in conscious animals during the experiment. Renal haemodynamics was assessed at the end of treatment in anaesthetized rats. I3C administration resulted in severe hypertension with a rise in systolic BP from 118 ± 2 to 202 ± 3 mmHg, a loss of BW from 266 ± 5 to 228 ± 4 g and a rise in proteinuria from 14 ± 2 to 34 ± 3 mg day-1. Both doses of c-AUCB significantly attenuated the development of hypertension (systolic BP of 181 ± 4 and 176 ± 4 mmHg, respectively), the loss in BW (256 ± 4 and 259 ± 3 g, respectively) and the degree of proteinuria (27 ± 2 and 25 ± 3 mg day-1, respectively) to a similar extent. Moreover, c-AUCB prevented the reduction in renal plasma flow (5.4 ± 0.4 vs. 4.6 ± 0.3 ml min-1 g-1) and significantly increased sodium excretion (0.84 ± 0.16 vs. 0.38 ± 0.08 μmol min-1 g-1) during I3C administration. These data suggest that the oral administration of c-AUCB displays antihypertensive effects in Ren-2 transgenic rats with inducible malignant hypertension via an improvement of renal function.

Castration has antihypertensive and organoprotective effects in male but not in female heterozygous Ren-2 rats

Gender differences in the regulation of blood pressure (BP) and the contributions of the renin-angiotensin system remain controversial. We assessed the effect of castration on BP and organ damage, as well as angiotensin II (ANG II), estradiol and testosterone levels in heterozygous Ren-2 transgenic (TGR) rats and transgene-negative Hannover Sprague-Dawley control rats. Male TGR had severe hypertension throughout the experiment, while the BP of female TGR declined after 5 months to normotensive levels. Ovariectomy had no effect on BP, cardiac hypertrophy or proteinuria in female Ren-2 TGR. On the contrary, BP and cardiac hypertrophy were significantly reduced in castrated male TGR as compared to sham-operated TGR. Moreover, proteinuria in these animals was normalized to the levels of control rats. ANG II levels did not differ between male and female TGR, and no effect of castration on plasma and tissue ANG II levels was found either in male or female TGR at the end of the experiment. In conclusion, the contribution of the renin-angiotensin system to the gender difference in BP homeostasis seems to be negligible in aging heterozygous Ren-2 transgenic rats.

Despite similar reduction of blood pressure and renal ANG II and ET-1 levels aliskiren but not losartan normalizes albuminuria in hypertensive Ren-2 rats

The relationship between angiotensin II (ANG II) and endothelin-1 (ET-1) is known to be complex; both peptides can initiate and potentiate the gene expression of each other. This pilot study investigated the effects of the AT(1) receptor blocker losartan or the direct renin inhibitor aliskiren on mean arterial pressure (MAP) and albuminuria and the renal ANG II and ET-1 levels. 3-month-old male Ren-2 transgenic rats (TGR) were treated either with losartan (5 mg kg(-1) day(-1)) or aliskiren (10 mg kg(-1) day(-1)) for 10 weeks. At the end of the experiment, rats were decapitated and cortical and papillary parts of kidneys were separated. Plasma and tissue ANG II levels were measured by RIA and tissue ET-1 concentrations by ELISA. In all four groups of animals ET-1 levels were lowest in renal cortex and more than 100-fold higher in the papilla. Cortical and papillary ET-1 concentrations in untreated TGR significantly exceeded those of control HanSD rats and were significantly depressed by both drugs. In both strains, papillary ANG II concentrations were moderately but significantly higher than cortical ANG II, TGR exhibited higher ANG II levels both in cortex and papilla as compared to control HanSD rats. Aliskiren and losartan at the doses used depressed similarly the levels of ANG II in cortex and papilla and reduced ET-1 significantly in the renal cortex and papilla below control levels in HanSD rats. Albuminuria, which was more than twice as high in TGR as in HanSD rats, was normalized with aliskiren and reduced by 28% with losartan, although MAP was reduced to a similar degree by both drugs. Despite similar reductions of MAP and renal ET-1 and ANG II levels aliskiren appears to be more effective than losartan, at the doses used, in reducing albuminuria in heterozygous hypertensive Ren-2 rats.