Kidney adaptation in nitric oxide-deficient Wistar and spontaneously hypertensive rats

Effect of the antihypertensive drug enalapril on oxidative stress markers and antioxidant enzymes in kidney of spontaneously hypertensive rat

Oxidative stress has been suggested to play a role in hypertension and hypertension induced organ damage. This study examined the effect of enalapril, an antihypertensive drug, on oxidative stress markers and antioxidant enzymes in kidney of spontaneously hypertensive rat (SHR) and Nω -nitro-L-arginine methyl ester (L-NAME) administered SHR. Male rats were divided into four groups (SHR, SHR+enalapril, SHR+L-NAME, and SHR+enalapril+L-NAME). Enalapril (30 mg kg⁻¹ day⁻¹) was administered from week 4 to week 28 and L-NAME (25 mg kg⁻¹ day⁻¹) was administered from week 16 to week 28 in drinking water. Systolic blood pressure (SBP) was measured during the experimental period. At the end of experimental periods, rats were sacrificed; urine, blood, and kidneys were collected for the assessment of creatinine clearance, total protein, total antioxidant status (TAS), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and catalase (CAT), as well as histopathological examination. Enalapril treatment significantly enhanced the renal TAS level (P < 0.001) and SOD activity (P < 0.001), reduced the TBARS levels (P < 0.001), and also prevented the renal dysfunction and histopathological changes. The results indicate that, besides its hypotensive and renoprotective effects, enalapril treatment also diminishes oxidative stress in the kidneys of both the SHR and SHR+L-NAME groups.

Chlorella pyrenoidosa ameliorated L-NAME-induced hypertension and cardiorenal remodeling in rats

PURPOSE

Hypertension is one of the main factors causing cardiovascular diseases. The aim of the study is to investigate the effects of Chlorella pyrenoidosa on blood pressure and cardiorenal remodeling in rats with N (ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced endothelial dysfunction.

METHODS

Rats were fed a diet containing L-NAME (40 mg/kg) with or without chlorella (4 or 8 %) for 5 weeks. We found that chlorella retarded the development of hypertension and cardiorenal remodeling during the 5-week experimental period.

RESULTS

Although there was no difference in NO( x ) levels or plasma arginine concentrations, plasma and tissues ACE activities were significantly lower in the chlorella groups than in the L-NAME group. Moreover, tissue tumor necrosis factor-α concentrations and renal CYP4A expression were also lower in the chlorella group.

CONCLUSION

These results suggest that chlorella might ameliorate the elevation of blood pressure and show cardiorenal-protective effects in nitric oxide-deficient rats, and one possible mechanism might be mediated by its ACE inhibitory activity.

Rosuvastatin prevents proteinuria and renal inflammation in nitric oxide-deficient rats

OBJECTIVE

The aim of the present study was to assess the effects of rosuvastatin on renal injury and inflammation in a model of nitric oxide deficiency.

METHODS

Male Wistar rats were randomly divided into four groups (n = 10/group) and treated for 28 days with saline (CTRL); 30 mg/kg/day L-NAME (L-name); L-NAME and 20 mg/kg/day rosuvastatin (L-name+ROS-20); or L-NAME and 2 mg/kg/day rosuvastatin (L-name+ROS-2). Systolic blood pressure was measured by plethysmography in the central artery of the tail. The serum total cholesterol, triglycerides, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine, nitric oxide, interleukin-6, and tumor necrosis factor alpha levels were analyzed. Urine samples were taken to measure the albumin: urinary creatinine ratio. Kidneys were sectioned and stained with hematoxylin/eosin and Masson's trichrome. Immunohistochemical analysis of the renal tissue was performed to detect macrophage infiltration of the glomeruli.

RESULTS

The systolic blood pressure was elevated in the L-name but not the L-name+rosuvastatin-20 and L-name+rosuvastatin-2 groups. The L-name group had a significantly reduced nitric oxide level and an increased interleukin-6 and tumor necrosis factor alpha level, albumin: urinary creatinine ratio and number of macrophages in the renal glomeruli. Rosuvastatin increased the nitric oxide level in the L-name+rosuvastatin-2 group and reduced the interleukin-6 and tumor necrosis factor alpha levels, glomerular macrophage number and albumin:urinary creatinine ratio in the L-name+rosuvastatin-20 and L-name+rosuvastatin-2 groups.

CONCLUSION

Rosuvastatin treatment reduced glomerular damage due to improvement in the inflammatory pattern independent of the systolic blood pressure and serum lipid level. These effects may lead to improvements in the treatment of kidney disease.

Arbutus unedo prevents cardiovascular and morphological alterations in L-NAME-induced hypertensive rats Part I: cardiovascular and renal hemodynamic effects of Arbutus unedo in L-NAME-induced hypertensive rats

Hypertension induced by nitric oxide synthase inhibition is associated with functional abnormalities of the heart and kidney. The aim of the present study was to investigate whether chronic treatment with Arbutus unedo leaf (AuL) or root (AuR) aqueous extracts can prevent these alterations. Six groups of rats were used: control group received tap water; N(G)-nitro-l-arginine methyl-ester (L-NAME) group treated with L-NAME at 40 mg/kg/day; AuL and AuR groups received simultaneously L-NAME (40 mg/kg/day) and Au leaves or roots extract at the same concentration 250 mg/kg/day; l-arginine and enalapril groups received simultaneously L-NAME (40 mg/kg/day) and l-arginine at 50mg/kg/day or enalapril at 15 mg/kg/day. Treatment of rats during 4 weeks with L-NAME caused an increase of the systolic blood pressure (SBP) accompanied by a ventricular hypertrophy, an impairment of endothelium-dependent vasorelaxation, an increase of the cardiac baroreflex sensitivity and a decrease of water, sodium and potassium excretion. The co-administration of AuL or AuR extracts with L-NAME reduces the development of increased SBP, ameliorates the vascular reactivity as well as the baroreflex sensitivity and normalizes the renal function. AuR reduces the ventricular hypertrophy but AuL do not. Enalapril associated with L-NAME reverses the majority of alterations induced by L-NAME while l-arginine only lightly ameliorates the vascular reactivity. These results show that chronic treatment with Arbutus extract regress the development of hypertension and ameliorate cardiovascular and renal functions in NO deficient hypertension.

Adult cardiorenal benefits from postnatal fish oil supplement in rat offspring of low-protein pregnancies

We investigated the effect of fish oil (FO) treatment on cardiorenal structure of adult offspring from low-protein pregnancies. Three month old offspring were assigned to eight groups (four male groups and four female groups, n=8 each) (NP=normal-protein diet, LP=low-protein diet): NP, LP, NP plus FO, and LP plus FO. Left ventricle and kidney were analyzed with light microscopy and stereology. The both sexes of LP offspring showed 30% lower birth weights than the respective NP offspring and high blood pressure (BP) levels in adulthood which was efficiently reduced by FO treatment. In the heart, FO treated the cardiomyocyte hypertrophy, the vascularization impairment, and decreased the cardiomyocyte loss usually observed in adult LP offspring. In the kidney, FO treated, in the male, the imbalance of the cortex-to-medulla ratio observed in both sexes of LP offspring, and reduced the glomeruli loss in the LP offspring. The positive correlation between the number of cardiomyocyte nuclei later in life and the body mass (BM) at birth was significant only in both sexes of LP offspring and this correlation disappeared in LP plus fish oil offspring. The positive correlation between the number of glomeruli later in life and the BM at birth was significant in NP male offspring and in both sexes of LP offspring. In conclusion, FO supplement, which is a rich source of n-3 fatty acids (DHA and EPA), has beneficial effects on BP control and cardiac and renal adverse remodeling usually seen in offspring of the LP pregnancies.

Different edible oil beneficial effects (canola oil, fish oil, palm oil, olive oil, and soybean oil) on spontaneously hypertensive rat glomerular enlargement and glomeruli number

We have tested the different edible oil effects on the blood pressure (BP) control and the following glomerular protection. Six groups of 12-week-old male spontaneously hypertensive rats (SHR) (n = 5), have received different edible oils (fish, canola, palm, olive, and soybean) or a placebo by gavage for 13 weeks. Renal cortex was analyzed through light microscopy and stereology. Usual BP increase, glomerulosclerosis, glomerular enlargement, and glomeruli loss in SHR has been prevented (fish, canola and palm oils) or attenuated (olive and soybean oils) by these oil long-term administration. The most favorable effect has been seen in the fish oil administration (source of n-3 polyunsaturated fatty acids, PUFA, eicosapentaenoic and docosahexaenoic acids), followed by both canola and palm oils (source of n-3 PUFA plus n-9 monounsaturated, MUFA, and saturated fatty acid, respectively), and finally both olive and soybean oils (source of n-9 MUFA and n-6 PUFA, respectively).

Renal endothelial effects of antihypertensive therapy

PURPOSE OF REVIEW

To review the influence of antihypertensive therapy on the contribution of nitric oxide (NO) to renal perfusion in essential hypertension.

RECENT FINDINGS

The contribution of endothelium-derived NO to renal perfusion can be examined in detail by studying isolated glomerular arterioles and by immunohistochemical techniques. Only few functional studies in human arterial hypertension exist analysing the role of NO for renal perfusion and the change in renal NO bioavailability due to arterial hypertension and its modification by antihypertensive therapy.

SUMMARY

NO critically contributes to renal perfusion. There is evidence of reduced but also of unchanged NO bioavailability in the renal vasculature of patients with arterial hypertension both from protein expression and functional studies. In particular, drugs interacting with the renin-angiotensin-aldosterone system (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and aldosterone antagonists) and third-generation beta blockers are promising candidates to improve renal endothelial function. It is not yet clear whether these specific effects translate into prevention of nephrosclerosis.