SHR Kidneys Research Articles

The renal excretory responses to acute renal interstitial angiotensin (1-7) infusion in anaesthetised spontaneously hypertensive rats.

This study investigated the impact of intrarenal angiotensin 1-7 (Ang [1-7]) infusion on renal excretory function in a rat model of hypertension. Eleven-week-old spontaneously hypertensive rats (SHRs, n=7) and Han Wistar controls (NCR, n=7) were anaesthetised with sodium pentobarbital (60mg/kg i.p.) and prepared for the measurement of mean arterial pressure (MAP) and left renal function during renal interstitial infusion of Ang (1-7) (50ng/min). The kidneys were harvested, the renal cortex and medulla separated, prepared for measurement of Ang II and Ang (1-7) and Western blot determination of AT1 and Mas receptor protein expression. MAP, glomerular filtration rate (GFR), urine flow (UF) and absolute sodium excretion (UNaV) were 109±16mmHg, 4.4±1.0mL/min/kg, 102±16µL/min/kg and 16±3µmol/min/kg, respectively in the NCR and 172±24mmHg, 3.4±0.7mL/min/kg, 58±30μL/min/kg and 8.6±4.8μmol/min/kg respectively in the SHR. Ang (1-7) increased UF (31%), UNa V (50%) and fractional sodium excretion (FENa+ ) (22%) in the NCR group (all p<0.05) but had no effect on GFR in either group. The magnitudes of the Ang (1-7)-induced increases in UF and UNa V were significantly blunted in the SHR group (model×drug p<0.05). The renal cortical AT1: Mas receptor expression ratio was significantly higher in the SHR group (p<0.05) but renal Ang II and Ang (1-7) levels were not statistically different between groups. The Ang (1-7)-induced increases in sodium and water excretion were impaired in the SHR group in the context of an unstimulated RAS. The decrease in responsiveness of the SHR kidney to Ang (1-7) appears to be associated with higher levels of AT1 receptor expression in the renal cortex.

The soybean bioactive peptide VHVV alleviates hypertension-induced renal damage in hypertensive rats via the SIRT1-PGC1α/Nrf2 pathway

• The peptide VHVV may suppress hypertensive renal damage. • Changes in the hypertensive kidney were restored by VHVV. • VHVV modulated oxidant defense mechanisms in the hypertensive kidney. • The cellular mitochondrial equilibrium in the SHR kidney was maintained by VHVV. • SIRT1-PGC1α/Nrf2 were activated by VHVV, enhancing ROS scavenging in SHR kidney. Hypertension triggers oxidative stress, causing dysfunction in organs, including the brain, heart, and kidney. In this study, we examined the potential renal benefit of the soybean bioactive peptide VHVV by in silico analysis and in spontaneously hypertensive rats. Sixteen-week-old spontaneously hypertensive rats were divided into 3 groups and treated with or without VHVV or captopril. Age-matched Wistar-Kyoto rats were used as normotensive control group. The rats were sacrificed after 8 weeks of treatment, and kidneys were analyzed to demonstrate the efficacy of VHVV. In silico analysis confirmed the antihypertensive activity of VHVV. In animal study, VHVV induced antioxidant defense and modulated mitochondrial homeostasis in the hypertensive kidney via SIRT1-PGC1α/Nrf2 pathway. Hence, improvements in renal cells were attributed to the suppression of inflammation and apoptosis, and the architecture of the hypertensive kidney was restored after peptide treatment. Overall, VHVV exhibited therapeutic effects by decreasing renal damage caused by hypertension-induced free radicals.

Antihypertensive Activity of Eucommia Ulmoides Oliv: Male Flower Extract in Spontaneously Hypertensive Rats

Eucommia ulmoides Oliv. is a traditional medical plant in Asia; however, it is still unknown whether Eucommia male flowers have an antihypertensive activity. In this study, we found that the aqueous extract of Eucommia ulmoides Oliv. male flowers can lower the blood pressure of SHR in a dose-dependent manner. Mechanistic studies suggested that the aqueous extract of male flowers can promote the mRNA and protein expressions of ACE2 in the kidney of SHR. ELISA assay showed that the plasma levels of ANG II was decreased, while ANG-(1–7) was increased in SHR treated with the aqueous extract of male flowers. ACE2 inhibitor DX600 can reverse the aqueous extract of Eucommia ulmoides Oliv. male flower-induced downregulation of Ang II and upregulation of Ang-(1–7), as well as the reduction of blood pressure in SHR. Moreover, Ang-(1–7)-Mas receptor antagonist A-779 abolished the antihypertensive effects of the aqueous extract of Eucommia ulmoides Oliv. male flower in SHR. The aqueous extract of Eucommia ulmoides Oliv. male flowers exhibited an antihypertensive action through the activation of ACE2-Ang-(1–7)-Mas signaling pathways in spontaneously hypertensive rats.

Abstract P123: Traditional Chinese Herbal Qian Yang Yu Yin Granules Treat Renal Damage in Spontaneously Hypertensive Rats by Inhibiting Renal Fibrosis

Background: Qian Yang Yu Yin Granules (QYYYG) is a Chinese herbal formula. It has been used in the clinical treatment of hypertensive renal impairment for more than 30 years. The pilot study curative effect is distinct. Methods: We elucidated the mechanisms underlying the therapeutic benefits of QYYYG, validate the drug-target predicted by the systems pharmacology analysis. WKY as control group. SHR were randomly divided into 3 groups: SHR, SHR+ Valsartan(0.03g/kg/d) and SHR +QYYY(5g/kg/d). WKY and SHR were gavage by distilled water. ELISA detected renal damage, tubular injury and fibrosis markers. HE and Masson staining to observe the general view and fibrosis degree. Results: After 4 weeks treatment, QYYYG reduced the levels of blood pressure and the expression of mALB, α1-MG, β2-MG, NGAL, KIM-1 and IL-18. HE staining of SHR kidneys showed classical pathological lesions including accumulation of extracellular matrix, infiltration of inflammatory cells and apparent interstitial fibrosis where renal fibrosis. These pathologic changes were reversed by QYYYG. The serum levels of LN, HA, pro-Col III and Col IV was also decreased. Similar results were found with Masson staining. RT-qPCR selected confirmed the reduced expression of TGF-β and the downstream fibrotic genes, closely associated with EMT in renal fibrosis. Overall, the therapeutic effects of QYYYG on renal fibrosis were consistent with those predicted by pathway analysis. Conclusions: Network-based analyses such as those described here may contribute to the holistic understanding and pharmacological evaluation of herbal remedies. QYYYG was validated as an effective treatment for hypertensive renal fibrosis.

MARcKS and nAP-22 proteins mRnA expression in renal cortex and renal medulla of rats with spontaneous hypertension

Objective. To study the changes in mRNA expression level of two main protein kinase C substrates — MARCKS and NAP-22 — in rats with spontaneous hypertension (SHR rats) and in normotensive control rats (WKY rats) in renal cortex, renal medulla and total kidney. We also aimed at the identification of possible interstrain differences between the mRNA expression levels.Design and methods.We assessed the level of MARCKS and NAP-22 mRNA by real-time polymerase chain reaction in male SHR and WKY (as a normotensive control) rats.Results. In SHR rats, MARCKS mRNA expression level in renal cortex was 1,5 times higher than in renal medulla (p = 0,0001) and also higher than in total kidney (p = 0,001), in renal medulla it was lower than in total kidney (p = 0,002). In WKY rats, MARCKS mRNA expression level in renal cortex was higher than in renal medulla (p = 0,0005). There was no differences neither between renal cortex and total kidney (p = 0,011), nor between renal medulla and total kidney (p = 0,716). In SHR rats, NAP-22 mRNA expression level in renal cortex was twofold higher than in renal medulla (p = 0,001), in renal medulla it was lower than in total kidney (p = 0,005), the differences between renal cortex and total kidney were less significant (p = 0,011). In WKY rats, NAP-22 mRNA expression level in renal cortex was 1,5 times higher than in renal medulla (p = 0,001), while in renal medulla it was lower than in total kidney (p = 0,002). There was no significant difference in NAP-22 mRNA expression level between renal medulla and total kidney (p = 0,011). There were no significant interstrain differences in the animal groups either in the levels of MARCKS mRNA expression in renal cortex (p = 0,872), in renal medulla (p = 0,024) or in total kidney (p = 0,520). Neither there were differences in the levels of NAP-22 mRNA expression in cortex (p = 0,028), in medulla (p = 0,028) and in total kidney (p = 0,978).Conclusions. In both SHR and WKY rat strains, the level of MARCKS and NAP-22 mRNA expression in cortical and medullary kidney layers is different, in WKY rats these differences are less pronounced. At the same time, interstrain differences in NAP-22 and MARCKS mRNA expression levels in cortical, medullary layers and in total kidney of SHR and WKY rats were not found.

2267 Radiofrequency renal denervation attenuates kidney fibrosis in spontaneously hypertensive rats

OBJECTIVES/SPECIFIC AIMS: The goal of this study was to investigate whether RF-RDN attenuates renal fibrosis and inflammation in SHR with established hypertension. METHODS/STUDY POPULATION: Twenty-two-week-old SHR received bilateral RF-RDN or Sham-RDN (Biosense Webster Stockert 70 generator and RF-probe). Four weeks later, SHR were sacrificed and paraffin sections of kidneys were stained for fibrosis by Masson’s trichrome staining. Kidney tissue were homogenized for measurement of cytokines levels by ELISA. RESULTS/ANTICIPATED RESULTS: The results showed that Sham-RDN treated SHR had extensive fibrosis as demonstrated by moderate thickening of Bowman’s capsule, collagen deposition in glomerulus, extensive tubulointerstitial fibrosis, and segmental glomerulosclerosis. In contrast, RF-RDN significantly reduced each of these pathological components of fibrosis in kidney cortex and medulla as compared with Sham-RDN treated kidneys. In other studies, RF-RDN decreased B cells, CD4+ T cells, and CD8+ T cells in the kidney of SHR as measured by flow cytometry. Meanwhile, kidney tissue levels of IL-17, INF-γ, MIP-3a, TNF-α, and TGF-β were decreased as compared with respective levels in Sham-RDN. DISCUSSION/SIGNIFICANCE OF IMPACT: Together, these findings demonstrate that removal of the influence of heightened renal sympathetic activity by RF-RDN decreases kidney inflammatory markers and attenuates renal fibrosis in hypertensive SHR.

Augmented myogenic constriction in the SHR pre‐glomerular renal arteries protects the kidneys from elevated blood pressure

BackgroundSpontaneously Hypertensive Rats (SHR) have chronically elevated blood pressures (BPs) at 30 weeks of age (systolic: 191.0 ± 1.0, diastolic: 128.8 ±0.9). However, despite this chronic malignant hypertension, SHR kidneys remain relatively free of pathology and do not display significant proteinuria, due to having an augmented myogenic constriction (MC) in their kidneys [1–2]. In contrast to the SHR, high‐salt fed Dahl Salt Sensitive (DSS) rats have lower BPs (systolic: 163.2 ± 1.4, diastolic: 119.4 ± 1.1), yet show extensive renal pathology, proteinuria, and blunted myogenic response (MR) in the pre‐glomerular vessels. We hypothesize that augmented MC in the SHR pre‐glomerular vessels is due to prostanoid synthesis, providing renal protection.Methods/ResultsTo investigate this hypothesis, we used the inhibitor of prostaglandin H2 synthesis, indomethacin, in the SHR and WKY pre‐glomerular arteries. We also utilized N omega‐nitro‐L‐arginine (LNNA) to examine the effect of nitric oxide blockade on MC, and nifedipine to determine the dependence of MR on L‐type calcium channels. Further, we used a second vascular bed, the mesenteric arcades, to assess the effects of these modulators on myogenic tone. The results showed an enhanced MR in the SHR pre‐glomerular vessels compared to the WKY. Indomethacin attenuated MC in both WKY and SHR renal arteries and nifedipine completely blocked this response in both WKY and SHR pre‐glomerular vessels. In mesenteric arteries, indomethacin decreased MR at high intraluminal pressures in the WKY, and lower pressures in the SHR. LNNA did not change MR in either WKY or SHR, while nifedipine inhibited MC in both WKY and SHR vessels.ConclusionsSHR pre‐glomerular arteries show an augmented MC compared to WKY vessels. Prostaglandin increases MC in both WKY and SHR renal arteries. In mesenteric arteries, prostaglandin increases MC at high intraluminal pressures in WKY, but lower pressures in the SHR. Nitric oxide does not affect MR in mesenteric arteries, but L‐type calcium channels play a key role in this response in both renal and mesenteric vessels.Support or Funding InformationThis work was supported by Canadian Institutes of Health Research grants to Dr. Jeffrey G. Dickhout (PJT148499).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Nicotine Mediates CD161a+ Renal Macrophage Infiltration and Premature Hypertension in the Spontaneously Hypertensive Rat.

Renal inflammation contributes to the pathophysiology of hypertension. CD161a+ immune cells are dominant in the (SHR) spontaneously hypertensive rat and expand in response to nicotinic cholinergic activation. We aimed to phenotype CD161a+ immune cells in prehypertensive SHR after cholinergic activation with nicotine and determine if these cells are involved in renal inflammation and the development of hypertension. Studies used young SHR and WKY (Wistar-Kyoto) rats. Splenocytes and bone marrow cells were exposed to nicotine ex vivo, and nicotine was infused in vivo. Blood pressures, kidney, serum, and urine were obtained. Flow cytometry, Luminex/ELISA, immunohistochemistry, confocal microscopy, and Western blot were used. Nicotinic cholinergic activation induced proliferation of CD161a+/CD68+ macrophages in SHR-derived splenocytes, their renal infiltration, and premature hypertension in SHR. These changes were associated with increased renal expression of MCP-1 (monocyte chemoattractant protein-1) and VLA-4 (very-late antigen-4). LLT1 (lectin-like transcript 1), the ligand for CD161a, was overexpressed in SHR kidney, whereas vascular cellular and intracellular adhesion molecules were similar to those in WKY. Inflammatory cytokines were elevated in SHR kidney and urine after nicotine infusion. Nicotine-mediated renal macrophage infiltration/inflammation was enhanced in denervated kidneys, not explained by angiotensin II levels or expression of angiotensin type-1/2 receptors. Moreover, expression of the anti-inflammatory α7-nAChR (α7-nicotinic acetylcholine receptor) was similar in young SHR and WKY rats. A novel, inherited nicotinic cholinergic inflammatory effect exists in young SHR, measured by expansion of CD161a+/CD68+ macrophages. This leads to renal inflammation and premature hypertension, which may be partially explained by increased renal expression of LLT-1, MCP-1, and VLA-4.

Abstract P063: Pitavastatin Has Antihypertensive and Renoprotective Effects With Upregulation of No System and Down-regulation of Oxidative Stress in the Kidney of Spontaneously Hypertensive Rats

Clinical trials have demonstrated renoprotective effects of atorvastatin (ATV) and pitavastatin (PTV), which belong to the strong statins, are more potent than other statins. We reported previously that ATV attenuated the development of hypertension in SHR with increasing the endothelial and neuronal NO synthases (eNOS, nNOS) expressions in the kidney, whereas ATV inhibited the eNOS phosphorylation at serin1177 (J Hypertes 28: 2278-2288, 2010). To clarify the mechanisms of renoprotective effects of PTV, the present study examined the effects of PTV on blood pressure, renal functions, NOS and oxidative stress in the kidney of SHR. Five-week-old, male SHR were given orally PTV (2mg/kg/day) or vehicle for 8 weeks. The systolic blood pressure (SBP) was measured. The NOS expression and eNOS phosphorylation were analyzed by Western blot. The NADPH oxidase activity was measured by the lucigenin-enhanced chemiluminescence method. PTV attenuated the progression of hypertension (220 ± 8 vs. 177± 4 mmHg, P&lt;0.01) and albuminuria (684 ± 66 vs. 398 ± 42 mg/day, P&lt;0.01) without changing plasma total cholesterol or creatinine. PTV increased the eNOS and nNOS expressions in the outer and inner medulla of the kidney (eNOS; by 182% and 186%, nNOS; by 315% and 194%, P&lt;0.01). PTV significantly stimulated the eNOS phosphorylation at serin1177 in the inner medulla and inhibited the eNOS phosphorylation at threonine495 in the outer and inner medulla. PTV decreased hydrogen peroxide (13.4 ± 2.1 vs. 6.1 ± 1.2 nmol/day, P&lt;0.05) and thiobarbituric acid reactive substances (TBARS) (236.6 ± 12.4 vs. 198.3 ± 10.6 nmol/day, P&lt;0.05) in the urine and the NADPH oxidase activity (42681± 2515 vs. 32381 ± 1995 c.p.m/mg protein, P&lt;0.01) in the renal cortex. These results indicate that PTV attenuates the development of hypertension and albuminuria in SHR with increasing the eNOS and nNOS expressions, changing the eNOS phosphorylation to an active form and mitigating oxidative stress in the kidney. The antihypertensive and renoprotective effects of PTV may be mediated in part by an upregulation of NO system and down-regulation of oxidative stress in the kidney.

733 Differential transcriptomicS of indapamide and hydrochlorothiazide in SHR kidney

Background: Indapamide (INDA) and hydrochlorothiazide (HCT) are antihypertensive diuretics but only indapamide was shown to prevent morbi/mortality. We and others have shown that they have distinct effects on vascular proliferation. Objective and methods: Our goal was to compare whole transcriptome in kidneys of SHR treated with IND, HCT and untreated controls (CTL) in order to unveil gene pathways resulting from these treatments. Eighteen male SHR rats received either vehicle, IND (0,24 mg/kg/d) or HCT (1,5 mg/kg/d) for 3 weeks and kidney transcriptomics analysis was performed using Affymetrix Rat Exon 1.0 ST. Results: 645 and 593 genes were differentially expressed by HCT and INDA compared to CTL. 218 genes were modulated by both drugs in the same direction. Among common genes, 3 Kallikreins displayed a significantly higher expression (KLK1 1,66 fold) while calpain 6 (CAPN6, 1,30 fold) exhibited a significantly lower expression by INDA compared to HCT compatible with the higher hypotensive and vasculoprotective effects of indapamide. We observed a differential effect on T2D susceptibility gene expression, including TCF7L2, compatible with a higher diabetogenic effect of HCT compared to INDA. Several genes modulated by HCT were found to be associated with pathways related to cancer, cell growth and proliferation while, on the contrary, the genes modulated by INDA treatment were associated to cell quiescence (lower ploidy). Conclusion: The data indicate that a possible difference between the 2 drugs could reside in their differential capacity to induce hypotensive and proliferative genes. Further studies are required to translate these observations to humans.

Hypertension affects the regulatory effect of nitric oxide on the respiratory chain

Nitric oxide (NO) synthesized from mitochondrial nitric oxide synthase (NOSmt) contributes to the regulation of oxidative phosphorylation by inhibiting ATP synthesis through the binding of NO to cytochrome c oxidase complex (complex IV) of the electron transport chain (ETC). We hypothesize that during hypertension the regulation of the ETC exerted by NO could be affected and could lead to a disruption in the mitochondrial energetic metabolism. Basal oxygen consumption during state 3 was increased in liver and kidney mitochondria from SHR of 1 and 7‐m.o. as compared with WKY animals of the same age. The sensitivity of complex IV to SNAP inhibition was lower in liver and kidney mitochondria from 7‐m.o. SHR as compared with mitochondria from WKY animals of the same age. Differential susceptibility to inhibition by SNAP was observed in complex IV activity from SHR rats of 7 months old for both organs. Activity of complex IV was inhibited with SNAP in a concentration‐dependent fashion in both WKY and SHR kidney and liver mitochondria from 1‐m.o. rats. The results suggest that hypertension lead to changes in ETC activity at the level of complex IV, which may be related with assembly defects of this complex during hypertension reported by others and contributes to mitochondrial dysfunction in kidney and liver during hypertension progression.

Increased decorin mRNA expression leads to larger collagen fibril diameter in SHR kidney cortex

It has been shown that the renal hypertensive damage in SHR is accompanied by changes in the synthesis, deposition and breakdown of collagen, in particular in the juxtamedullary cortex (JMC). In the present study, we investigated gene expression using Illumina beadarray microarrays comparing renal cortex from 60 week old SHR with WKY rats.The results showed increased expression of decorin (2.3 fold increase P&lt;0.01). Decorin is a small leucin rich protein (SLRP) which binds collagen and is important in collagen fibril formation. In addition, fibronectin, another SLRP was also increased (1.8 fold increase P&lt;0.01). Finally several forms of fibrillar collagen were upregulated, collagen Ia1 (1.4 fold increase P&lt;0.01), collagen IIIa1 (2.7 fold increase P&lt;0.01) and collagen Ia2 (2.9 fold increase P&lt;0.01). This indicates a changed collagen fibril composition and assembly process.Further, collagen fibril diameter measurements were performed using TEM. The fibril diameters were increased in the JMC of SHR compared to the outer cortex (P&lt;0.05), while diameters in superficial and juxtamedullary cortex were not different in WKY.In conclusion, renal interstitial fibrosis in JMC of SHR is composed of thicker collagen fibrils. This increased fibril diameter may be a result of increased SLRP expression in damaged cortex as well as a changed composition of the collagen fibrils.

Role of G Protein-Coupled Receptor Kinase-2 in Peroxisome Proliferator-Activated Receptor Gamma-Mediated Modulation of Blood Pressure and Renal Vascular Reactivity in SHR

Background: Peroxisome proliferator-activated receptor γ (PPARγ), a nuclear transcription factor, modulates the expression/activity of G protein-coupled receptors (GPCRs), but its role in GPCR signaling is not clear. Increased GPCR kinase-2 (GRK-2) activity and receptor desensitization have been reported in hypertension. Method: In this study we investigated the role of GRK-2 in PPARγ-mediated blood pressure regulation in hypertension. SHR or WKY rats were treated with GW1929, a selective PPARγ ligand (0.5 mg/kg/day), or vehicle for 2 months. Systolic blood pressure (tail cuff plethysmography), whole kidney perfusion (laser scanner) and renal vascular reactivity (isolated perfused kidney) was determined. Results: GW1929 significantly reduced blood pressure (20 ± 1%) and increased renal perfusion (61 ± 3%) in SHR compared to WKY rats. Vasoconstriction to phenylephrine (100 μg) in the isolated perfused kidney was greater in SHRs (29 ± 1%) compared to WKY rats and this was abolished by GW1929. GW1929 enhanced acetylcholine-induced (30–300 μg) and sodium nitroprusside-induced vasodilatation in SHR by 46 ± 2% (p < 0.05) and 33 ± 2% (p < 0.05), respectively. Isoprenalin-induced (5–30 μg) vasodilatation was 43 ± 2% lower in SHR compared to WKY and GW1929 enhanced this vasodilatation by 55 ± 2%. In SHR kidney, GW1929 enhanced expression of PPARγ mRNA (34 ± 1%) but reduced that of GRK-2 (31 ± 3%). Conclusion: We suggest that downregulation of PPARγ but upregulation of GRK-2 increases blood pressure and impaired renal vascular reactivity in SHR and that PPARγ-mediated improvement in hypertension may involve transcriptional regulation of GRK-2 function.

Effects of high salt diet on NF‐KB and CREB DNA binding activity in heart, kidney and hypothalamus of SHR

In Dahl S or SHR on high salt diet, activation of NF‐κB contributes to cardiac hypertrophy and renal damage, which may be offset by activation of CREB. The brain RAAS mediates the salt‐induced hypertension, possibly by NF‐κB in the PVN. We assessed effects of high salt diet on DNA‐binding activity of NF‐κB and CREB in the heart, kidney and PVN of WKY rats and SHR on high (8%) or reg (0.6%) salt diet for 2 or 4 weeks (n=6). NF‐κB and CREB DNA binding activity were studied by electrophoretic mobility shift assay.In WKY, high salt only increased CREB DNA binding activity in the LV and NFκB in the PVN. In SHR, high salt increased NF‐κB DNA‐binding activity in the heart and kidney, but decreased CREB binding activity in the heart, kidney, and the PVN.ConclusionHigh salt causes an inverse relationship between NF‐κB and CREB in the LV, kidney and PVN which may contribute to salt induced sympathetic hyperactivity, LV and renal hypertrophy in SHR.

Heme Oxygenase -1 Gene Therapy: Recent Advances and Therapeutic Applications

Heme oxygenase-1 (HO-1) is regarded as a sensitive and reliable indicator of cellular oxidative stress. Studies on carbon monoxide (CO) and bilirubin, two of the three (iron is the third) end products of heme degradation have improved the understanding of the protective role of HO against oxidative injury. CO is a vasoactive molecule and bilirubin is an antioxidant, and an increase in their production through an increase in HO activity assists other antioxidant systems in attenuating the overall production of reactive oxygen species (ROS), thus facilitating cellular resistance to oxidative injury. Gene transfer is used to insert specific genes into cells that are either otherwise deficient in or that underexpress the gene. Successful HO gene transfer requires two essential elements to produce functional HO activity. Firstly, the HO gene must be delivered in a safe vector, e.g., adenoviral, retroviral or leptosome based vectors, currently being used in clinical trials. Secondly, with the exception of HO gene delivery to either ocular or cardiovascular tissue via catheter-based delivery systems, HO delivery must be site and organ specific. This has been achieved in rabbit ocular tissues, rat liver, kidney and vasculature, SHR kidney, and endothelial cells [Abraham et al., 1995a; Abraham et al., 1995b; Abraham et al., 2002c; Quan et al., 2004; Sabaawy et al., 2000; Sabaawy et al., 2001; Yang et al., 2004]. In this review, we discuss the functional significance of the HO system in various pathophysiological conditions and the beneficial therapeutic applications of human HO gene transfer and gene therapy in a variety of clinical circumstances.

Na + ‐dependent neutral amino acid transporter ASCT2 is under‐expressed in SHR kidney

Na ⁺ ‐dependent neutral amino acid transporter ASCT2 is under‐expressed in SHR kidney

Effect of High Salt Intake on the Expression of B0AT1 and LAT2 Amino Acid Transporters in Spontaneous Hypertensive Rat

This study was performed to examine the response of two amino acid transport systems, potentially involved in L-DOPA uptake (Na+-independent LAT2 and Na+-dependent B0AT1) to salt load stimuli, in the renal cortex of the SHR and the normotensive Wistar-Kyoto rats (WKY). Animals were fed normal (NS) or high (HS - 1% saline as drinking water) salt diet for 24 hours. Kidney samples were collected, frozen in liquid N2, and stored at −80 degrees C before analysis for mRNA abundance. The renal dopaminergic system was evaluated: WKY failed to respond to HS with increases in the urinary dopamine excretion, at 12 weeks of age, while HS intake in SHR produced a 2-fold increase in the urinary excretion of dopamine. L-DOPA plasma levels in SHR during NS and HS intake were similar to those in WKY. RT-PCR quantification analysis revealed a decreased expression of LAT2 mRNA in WKY and SHR on HS intake. At 12 weeks of age, LAT2/4F2hc ratios in SHR on HS intake were significantly lower than in SHR fed a NS diet, which was not the case in WKY. Evaluation of the expression of Na+ dependent B0AT1, showed a significant decrease in both 4 and 12 week old WKY and in 4 week old SHR, fed HS diet. By contrast, HS intake produced a significant increase (~ 45% augment) in B0AT1 mRNA of SHR of 12 weeks of age. In conclusion, the increased renal dopamine production and excretion in SHR might be related to enhanced ability to take up L-DOPA at the kidney level. During HS, Na+ dependent B0AT1 is overexpressed in SHR kidney, probably contributing to the enhanced L-DOPA uptake, observed in the hypertensive phase. Differences in regulation of renal B0AT1 and LAT2 in SHR versus WKY may have to do with differences concerning sodium handling. Supported by grant POCTI/SAU-OBS/57916/2004.

Effects of benazepril on expression of aquaprotein-2 in SHR and WKY kidney

Effects of benazepril on expression of aquaprotein-2 in SHR and WKY kidney

A-type natriuretic peptide receptor in the spontaneously hypertensive rat kidney

Renal NPR-A binding characteristics was examined in SHR. Renal ANP binding sites of NPR-A showed a lower maximal binding capacity and higher affinity in SHR than in WKY at all intrarenal sites. Despite the lower B max in SHR, both ANP 1–28 and ANP 5–25 stimulate similar or greater cGMP production in isolated glomeruli. Studies on guanylate cyclase from glomerular and papillary membranes have reported an increased basal and stimulated guanylate cyclase activity in SHR. The present study provides further evidences for altered NPR-A receptors in SHR kidney, which might act as a negative feedback in response to hypertension.

5,6-Epoxyeicosatrienoic Acid Mediates the Enhanced Renal Vasodilator Response to Arachidonic Acid (AA) in the SHR.

P109 The cytochrome P450-dependent renal vasodilator effect of arachidonic acid (AA) that is expressed when cyclooxygenase is inhibited and perfusion pressure (PP) is elevated, is enhanced in SHR. In kidneys perfused with Krebs’ solution and preconstricted with phenylephrine to increase PP to ca 200 mmHg, 5 μg of AA reduced PP by 92 ± 10 mmHg in SHR compared to 44.5 ± 5 mmHg for WKY rats. In contrast, the dilator effects of acetylcholine (Ach; 0.1 μg) or sodium nitroprusside (SNP; 1 μg) were not different. As the response to AA was inhibited by ETYA (4 μM), an inhibitor of all AA oxygenase pathways, and also inhibited by the selective epoxygenase inhibitors, miconazole (0.3 μM) and MSPPOH (12 μM), we concluded that the vasodilator mediator(s) of the AA response was most likely an epoxyeicosatrienoic acid (EET). We therefore, assessed the renal vascular responses to EETs in the SHR and WKY. We found that 5,6-EET, 8,9-EET, and 11,12-EET were dilators in both SHR and WKY, whereas 14,15-EET produced constriction. 5,6-EET was the most potent dilator of the EET regioisomers in the SHR resulting in a decrease in PP of 56 ± 5 mmHg compared to 12 ± 4 mmHg for 8,9-EET and 15 ± 4 mmHg for 11,12-EET. The decrease in PP elicited by 5 μg of 5,6-EET was greater in SHR, 56 ± 5 mmHg compared to 29 ± 4 mmHg for WKY rats whereas the responses to the other EET regioisomers did not differ. We measured the release of EETs from SHR and WKY kidneys in response to 5 μg of AA, by GC-MS in negative ionization mode using selective ion monitoring. The release of 5,6-EET was increased in SHR (from a basal level of 0.5 ± 0.04 to 0.9 ± 0.1 ng/min; P&lt;0.05) compared to WKY (from a basal level of 0.6 ± 0.2 to 0.7 ± 0.2 ng/min), whereas the release of the other EETs were not different. We suggest that 5,6-EET is the most likely mediator of the AA response and that the augmented vasodilator response to AA in the SHR kidney might be linked to increased production of and responsiveness to 5,6-EET.