2K1C Renovascular Hypertension Research Articles

Caloric restriction improves inflammation in different tissues of the Wistar rats with obesity and 2K1C renovascular hypertension.

Renovascular hypertension (RHV) is the cause of high blood pressure due to left renal ischemia, and obesity and hypertension cause an inflammatory response. This work analyzed the inflammatory and tissue repair profile in renal, hepatic, and cardiac tissues in an animal model of RVH associated with a high-fat diet and caloric restriction. The expressions of RORγ-t, IL-17, T-bet, and TNF-α decreased and IFN-γ increased in the right kidney. In relation to the left kidney, caloric restriction decreased the expression of IFN-γ. In the liver, caloric restriction decreased RORγ-t, IL-17, and T-bet. Hypertension associated with obesity decreased the expression of IFN-γ, while caloric restriction increased. In the right kidney, hypertension and obesity, associated or not with caloric restriction, increased the area of collagen fibers. In the heart and liver, caloric restriction reduced the area of collagen fibers. Caloric restriction increased vascular endothelial growth factor, reduced levels of growth transformation factor-β1 (TGF-β), and increased collagen I in the left kidney. Hypertension/obesity, submitted or not having caloric restriction, increased TGF-β in liver. The results suggest that caloric restriction has beneficial effects in lowering blood pressure and regulating tissue proinflammatory cytokines. However, there was no change in the structure and composition of tissue repair markers.

Deletion of the Transient Receptor Potential Vanilloid 1 Channel Attenuates Sympathoexcitation and Hypertension and Improves Glomerular Filtration Rate in 2-Kidney-1-Clip Rats.

Renal denervation lowers arterial blood pressure in both clinical populations and multiple experimental models of hypertension. This therapeutic effect is partly attributed to the removal of overactive renal sensory nerves. The TRPV1 (transient receptor potential vanilloid 1) channel is highly expressed in renal sensory nerves and detects changes in noxious and mechanosensitive stimuli, pH, and chemokines. However, the extent to which TRPV1 channels contribute to 2-kidney-1-clip (2K1C) renovascular hypertension has not been tested. We generated a novel Trpv1-/- (TRPV1 knockout) rat using CRISPR/Cas9 and 26-bp deletion in exon 3 and induced 2K1C hypertension. The majority (85%) of rat renal sensory neurons retrogradely labeled from the kidney were TRPV1-positive. Trpv1-/- rats lacked TRPV1 immunofluorescence in the dorsal root ganglia, had a delayed tail-flick response to hot but not cold water, and lacked an afferent renal nerve activity response to intrarenal infusion of the TRPV1 agonist capsaicin. Interestingly, 2K1C hypertension was significantly attenuated in male Trpv1-/- versus wild-type rats. 2K1C hypertension significantly increased the depressor response to ganglionic blockade, total renal nerve activity (efferent and afferent), and afferent renal nerve activity in wild-type rats, but these responses were attenuated in male Trpv1-/- rats. 2K1C hypertension was attenuated in female rats with no differences between female strains. Finally, glomerular filtration rate was reduced by 2K1C in wild-type rats but improved in Trpv1-/- rats. These findings suggest that renovascular hypertension requires activation of the TRPV1 channel to elevate renal afferent and sympathetic nerve activity, reduce glomerular filtration rate, and increase arterial blood pressure.

Influence of Intestinal Barrier on Alleviating an Increase in Blood Pressure by Sodium Alginate Intake in 2-Kidney, 1-Clip Renovascular Hypertensive Rats.

Sodium alginate (SALG) is a substance derived from brown seaweed that has been shown to reduce blood pressure (BP). However, its effects on renovascular hypertension caused by 2-kidney, 1-clip (2K1C) are not yet clear. Previous research suggests that hypertensive rats have increased intestinal permeability, and that SALG improves the gut barrier in inflammatory bowel disease mouse models. Therefore, the goal of this study was to determine whether the antihypertensive effects of SALG involve the intestinal barrier in 2K1C rats. Rats were fed either a 1.0% SALG diet or a control diet for six weeks after being subjected to 2K1C surgery or a sham operation. The systolic BP was measured weekly, and the mean arterial BP was measured at the end of the study. Intestinal samples were taken for analysis, and plasma lipopolysaccharide (LPS) levels were measured. The results showed that BP in 2K1C rats was significantly higher than in SHAM rats when fed CTL, but not when fed SALG. The gut barrier in 2K1C rats was improved by SALG intake. Plasma LPS levels also differed depending on the animal model and diet. In conclusion, dietary SALG may alleviate 2K1C renovascular hypertension by altering the gut barrier.

S-51-6: RENOVASCULAR HYPERTENSION AND BRAIN: ROLE OF THE RENIN-ANGIOTENSIN SYSTEM AND SODIUM

Renovascular hypertension is a type of secondary hypertension. Renovascular hypertensive 2-kidney, 1-clip (2K1C) rats have an increased activity of the renin-angiotensin system, and it is an experimental model to study renovascular hypertension. Renovascular hypertensive 2K1C rats have an imbalance of RAS components in the brain, an impairment of the baroreflex and they present an increase in daily intake of hypertonic NaCl solution. Therefore, we focused on studying: 1) the effects of overexpression of RAS components in the in the nucleus of the solitary tract (NTS), a brainstem area involved with cardiovascular control, 2) the brain mechanisms involved with the sodium appetite (operationally defined as an ingestion of hypertonic NaCl solution) in 2K1C rats. In adult Holtzman rats, the left renal artery was partially occluded by a silver clip with an opening of 0.2 mm to induce 2K1C. The experiments started after 6 weeks (hypertension plateau). We observed that increasing angiotensin type 2 receptor (AT2R) expression in the NTS attenuated the development of renovascular hypertension and also reversed the impairment of the baroreflex observed in 2K1C rats. Furthermore, an observed decrease in mRNA levels of angiotensin-converting enzyme 2 in the NTS of 2K1C rats was restored to control levels after viral-mediated increases in AT2R at this site. Virally mediated blockade of an intracellular pathway activated by angiotensin II (ANG II) acting in type 1 receptor (AT1R) in the NTS attenuated the development of renovascular hypertension and also reversed the impairment of the baroreflex. Daily 0.3 M NaCl intake transiently increased from the 2nd to the 5th week after 2K1C surgery. On the 6th week, in spite of comparable daily 0.3 M NaCl intake between 2K1C and sham rats, water deprivation (used to induce sodium appetite) produced a greater increase 0.3 M NaCl intake in 2K1C rats. Moreover, this intake is totally blocked by central AT1R and mineralocorticoid receptor antagonism. These data demonstrated that ANG II acting in the AT1R in the NTS is involved with the development of hypertension and baroreflex impairment in 2K1C and that AT2 overexpression at the same site can counteract these effects. In addition, the results demonstrated the participation of ANG II and aldosterone acting centrally in the enhanced sodium intake in water deprived 2K1C rats.

Evaluation of involvement of adrenergic receptor modulator in hypertension induced experimental Vascular Dementia in Rats

Objective: Cerebrovascular and cardiovascular disease are considered as a major risk factor for the development of VaD. This study investigates the efficacy of nicergoline in 2K1C induced vascular endothelium dysfunction and related dementia. Methods: 2K1C renovascular hypertension has induced hypertension in Albino Wistar rats (male, 200-250g). Morris water maze (MWM), and attentional set shifting tests (ASST) were used to assess the spatial learning, memory, reversal learning, and executive functioning in animals. Mean artery blood pressure, serum nitrite/nitrate, vascular endothelial function, aortic superoxide anion, brains’ oxidative markers (thiobarbituric acid reactive species-TBARS, reduced glutathione-GSH, superoxide dismutase-SOD, and catalase-CAT), inflammatory markers (myeloperoxidase-MPO), calcium levels, acetylcholinesterase activity-and AChE ativity were also assessed. Nicergoline (5 mg/kg or 10 mg/kg p.o.) was used as the treatment drugs. Donepezil (0.5mgkg-1) was used as a positive control. Results: 2K1C rats showed reduction in learning, memory, reversal learning, executive functioning, impairment in endothelial function, increase in mean artery blood pressure, brains’ oxidative stress, inflammation, calcium levels, and AchE-activity. Administration of nicergoline significantly attenuated the 2K1C induced impairments in the behavioral, endothelial, and biochemical parameters. Conclusion: 2K1C renovascular hypertension induced impairment in behavioral, endothelial, and biochemical parameters which were attenuated by the administration of nicergoline. Therefore, nicergoline may be studied further for the assessment of their full potential in hypertension induced VaD.

Angiotensin II augments renal vascular smooth muscle soluble GC expression via an AT1 receptor-forkhead box subclass O transcription factor signalling axis.

Reduced renal blood flow triggers activation of the renin-angiotensin-aldosterone system (RAAS) leading to renovascular hypertension. Renal vascular smooth muscle expression of the NO receptor, soluble GC (sGC), modulates the vasodilator response needed to control renal vascular tone and blood flow. Here, we tested if angiotensin II (Ang II) affects sGC expression via an AT1 receptor-forkhead box subclass O (FoxO) transcription factor dependent mechanism. Using a murine two-kidney-one-clip (2K1C) renovascular hypertension model, we measured renal artery vasodilatory function and sGC expression. Additionally, we conducted cell culture studies using rat renal pre-glomerular smooth muscle cells (RPGSMCs) to test the in vitro mechanistic effects of Ang II treatment on sGC expression and downstream function. Contralateral, unclipped renal arteries in 2K1C mice showed increased NO-dependent vasorelaxation compared to sham control mice. Immunofluorescence studies revealed increased sGC protein expression in 2K1C contralateral renal arteries over sham controls. RPGSMCs treated with Ang II caused a significant up-regulation of sGC mRNA and protein expression as well as downstream sGC-dependent signalling. Ang II signalling effects on sGC expression occurred through an AT1 receptor and FoxO transcription factor-dependent mechanism at both the mRNA and protein expression levels. Renal artery smooth muscle, in vivo and in vitro, up-regulates expression of sGC following RAAS activity. In both cases, up-regulation of sGC leads to increased downstream cGMP signalling, suggesting a previously unrecognized protective mechanism to improve renal blood flow in the uninjured contralateral renal artery. This article is part of a themed issue on cGMP Signalling in Cell Growth and Survival. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.11/issuetoc.

Antiproteinuric and Hyperkalemic Mechanisms Activated by Dual Versus Single Blockade of the RAS in Renovascular Hypertensive Rats.

This study aimed to investigate the antiproteinuric and hyperkalemic mechanisms activated by dual renin-angiotensin system (RAS) blockade in renovascular hypertensive rats (2-kidney 1-clip model [2K-1C]). Six weeks after clipping the left renal artery or sham operation (2K), rats were treated with losartan, enalapril, or both drugs for two weeks. We found that 2K-1C rats displayed higher tail-cuff blood pressure (BP), increased non-clipped kidney Ang II concentration, and more pronounced urinary albumin excretion than 2K. BP was decreased by the treatment with either enalapril or losartan, and the combination of both drugs promoted an additional antihypertensive effect in 2K-1C rats. Renal Ang II content and albuminuria were reduced by either enalapril or losartan in monotherapy and restored to control levels by dual RAS blockade. Albuminuria in 2K-1C rats was accompanied by downregulation of the glomerular slit protein podocin, reduction of the endocytic receptors megalin and cubilin, and a marked decrease in the expression of the ClC-5 chloride channel, compared to 2K animals. Treatment with losartan and enalapril in monotherapy or combination increased the expression of podocin, cubilin, and ClC-5. However, only the combined therapy normalized podocin, cubilin, and ClC-5 protein abundance in the non-clipped kidney of 2K-1C rats. Renovascular hypertensive 2K-1C rats had a lower concentration of plasma potassium compared to 2K rats. Single RAS blockade normalized potassium plasma concentration, whereas 2K-1C rats treated with dual RAS blockade exhibited hyperkalemia. Hypokalemia in 2K-1C rats was accompanied by an increase in the cleaved activated forms of α-ENaC and γ-ENaC and the expression of β-ENaC. Combined RAS blockade but not monotherapy significantly reduced the expression of these ENaC subunits in 2K-1C rats. Indeed, double RAS blockade reduced the abundance of cleaved-α-ENaC to levels lower than those of 2K rats. Collectively, these results demonstrate that the antiproteinuric effect of dual RAS blockade in 2K-1C rats is associated with the restored abundance of podocin and cubilin, and ClC-5. Moreover, double RAS blockade-induced hyperkalemia may be due, at least partially, to an exaggerated downregulation of cleaved α-ENaC in the non-clipped kidney of renovascular hypertensive rats.

Regulation of connexins genes expression contributes to reestablishes tissue homeostasis in a renovascular hypertension model

Connexins (Cx) are essential for cardiovascular regulation and maintenance of cardio-renal response involving the natriuretic peptide family. Changes in the expression of connexins promote intercellular communication dysfunction and may induce hypertension, atherosclerosis, and several other vascular diseases. This study analyzed the expression of the genes involved in the renin-angiotensin system (RAS) and the relation of the connexins gene expression with the renovascular hypertension 2K1C in different tissues. The insertion of a silver clip induced renovascular hypertension 2K1C into the left renal artery. Biochemical measurements were made using commercial kits. Gene expression was evaluated in the liver, heart, and kidneys by RT-PCR. The genes investigated were LDLr, Hmgcr, Agt, Ren, Ace, Agtr1a, Anp, Bnp, Npr1, Cx26, Cx32, Cx37, Cx40 and Cx43. All genes involved in the RAS presented increased transcriptional levels in the 2K1C group, except hepatic Agt. The natriuretic peptides (Anp; Bnp) and the receptor genes (Npr1) appeared to increase in the heart, however, Npr1 decreased in the kidneys. In hepatic tissue, hypertension promoted increased expression of Cx32, Cx37, and Cx40 genes however, Cx26 and Cx43 genes were not influenced. Expression was upregulated for Cx37 and Cx43 in cardiac tissue in the 2K1C group, but Cx40 did not demonstrate any difference between groups. The stenotic kidney showed an upregulated expression for Cx37 vs Sham and contralateral kidney, although Cx40 and Cx43 were downregulated. Hypertension did not modify the transcriptional expression of Cx26 and Cx32. Therefore, this study indicated that RAS and cardiac response were regulated transcriptionally by renovascular hypertension 2K1C. Moreover, the results of connexin gene expression demonstrated differential transcriptional regulation in different tissues studied and suggest a relationship between cardiac and renal physiological changes as an adaptive mechanism to the hypertensive state.

Abstract P029: Aspartate And Potassium Aspartate May Contribute To A Mechanism By Which Saccharina Japonica Extract Attenuates Hypertension In 2-kidney, 1-clip Renovascular Hypertensive Rats.

Introduction: Saccharina japonica (SJ) is one of brown algae. The extract of SJ (SJE) is often used for soup stock in Japanese cuisine. We recently observed the decreases in blood pressure (BP) by intake of SJ or SJE diet in 2-kidney, 1-clip renovascular hypertensive (2K1C) rats. SJ is rich in aspartate (Asp), which is the umami taste of amino acid. The intake of Asp was reported to reduce BP in Dahl salt sensitive rats. As well, the potassium Asp (AspK) intake was reported to improve BP in hypertensive patients. 70% (70 of 100) of amino acids such as Asp are eluted into the SJE from SJ. Therefore, we hypothesized that Asp in SJE contributes to the mechanism of BP reduced by dietary SJE in 2K1C rats. In this study, we observed BP in 2K1C rats fed a diet containing Asp or AspK and investigated whether those diets alleviate hypertension to the same extent of the diet containing SJE. Methods: Male Sprague-Dawley rats (6 wks) were treated with sham operation (SHAM) or clipping the left renal artery (2K1C). After surgery, the rats fed a control diet (C), a diet containing Asp, AspK or SJE for 6 weeks. The content of SJE was set to be the same as that in our previous study. The amount of Asp in diet was set to be the same as that in our previous study which showed the antihypertensive effect of SJ. The amount of AspK in diet was set to be equimolar to Asp. The systolic BP (SBP) was measured by a tail-cuff method every week. At the end of the procedure, mean arterial BP (MAP) was measured in each rat under anesthesia. Results: Six weeks after the surgery, 2K1C-C significantly increased in SBP compared with SHAM-C (126±2 vs 159±4 mmHg, p<0.05). However, 2K1C-Asp (138±3), -AspK (142±4), and -SJE (135±4) decreased compared with 2K1C-C (p<0.05) respectively. MAP was significantly higher in 2K1C-C than in SHAM-C (162±3 vs 131±5, p<0.05). It showed a significant decrease in 2K1C-Asp (142±3), -AspK (148±3) and -SJE (144±4), compared with 2K1C-C (p<0.05), respectively. There were no significant differences among 2K1C-Asp, -AspK and -SJE, in either SBP or MAP. Conclusions: Asp and AspK may attenuate hypertension in 2K1C renovascular hypertension as much as SJE which contains similar quantities of Asp. It is possible that Asp and/or AspK eluted into SJE contributes to the mechanism of alleviating hypertension by SJE in 2K1C.

Immune profiles in experimental two-Kidney-one-cuff (2K-1C) model of renovascular hypertension that predicts reversible versus irreversible renal injury

Abstract Renal artery stenosis is common in the elderly population; biomarkers that predict response to restoration of blood flow have not been previously established. Methods We have previously shown in murine model that cuff removal 7 days (7D Cuff-off) after initial placement on the renal artery results in reversible injury whereas cuff removal 14 days (14D Cuff-off) after placement results in irreversible renal injury, when assessed at 28 days after initial surgery. Positive and negative controls consisted of cuff placement for 28 days (28D) and sham surgeries respectively. We performed RNASeq on whole renal cortex to identify innate immune pathways that correlate with reversible versus irreversible injury. Data were normalized to appropriate sham controls in all the groups. Induction of greater than log2 ratio > 2 and p < 0.00001 were considered significant (following adjustment for multiple comparisons). Results As assessed by RNASeq, progression of renal disease (14D Cuff-off & 28D mice) was associated with persistent upregulation of genes associated with T cell signaling and macrophage polarization compared to reversible injury (7D Cuff off). Upregulated genes included but not limited to: CCL5, CCR5, CCL2, CXCL1, CXCL9, CXCL10, CXCR3, TLR2, KLF6, CD74, CD4, CD14, CD44, CD83, CD84, IL1R1, IL1B, SPP1, AIF1, SLC7A2, TRAF1, S100A4, SLC9A9, CRIP1, CLEC7A, CLEC10A, EGR2, MGL2, SOCS2, CTLA2B, and FCGR1. Conclusion We have identified genes associated with T cell and macrophage activation that were down regulated in the 7D Cuff-off versus 14D Cuff-off and 28D mice; future studies in isolated T cells and macrophages will determine whether these genes represents biomarker(s) of renal disease progression in 2K-1C renovascular hypertension.

Fitness is improved by adjustments in muscle intracellular signaling in rats with renovascular hypertension 2K1C undergoing voluntary physical exercise

AimTo evaluate physical fitness and cardiovascular effects in rats with renovascular hypertension, two kidneys, one clip (2K1C) submitted to voluntary exercise (ExV). Main methods24 h after surgery (SHAM and 2K1C) rats were submitted to ExV for one week (adaptation). ExV adherent rats were separated into exercise (2K1C-EX and SHAM-EX) or sedentary (2K1C-SED and SHAM-SED) groups. After 4 weeks, exhaustion test, plasma lactate, cardiovascular parameters were evaluated and gastrocnemius muscle was removed for evaluation of gene expression of muscle metabolism markers (PGC1α; AMPK, SIRT-1, UCP-3; MCP-1; LDH) and of the redox process. Key findingsExV decreased blood lactate concentration and increased SOD and CAT activity and a SIRT-1 and UCP-3 gene expression in the gastrocnemius muscle of 2K1C-ExV rats compared to 2K1C-SED rats. Gene expressions of PGC1α, UCP-3, MCT-1, AMPK were higher in 2K1C-ExV rats compared to SHAM-SED rats. Blood pressure in 2K1C-ExV was lower compared to 2K1C-SED and higher in SHAM-SED rats. Reflex bradycardia in 2K1C-EX rats increased compared to 2K1C-SED and was similar to SHAM-SED. The variation in mean blood pressure induced by ganglion blocker hexamethonium and Ang II AT1 receptor antagonist, losartan in the 2K1C-ExV rats was smaller compared to the 2K1C-SED rats and it was similar to the SHAM-SED rats. SignificanceO ExV induced adaptive responses in 2K1C-ExV rats by decreasing sympathetic and Ang II activities and stimulating intracellular signaling that favors redox balance and reduced blood lactate concentration. These adaptive responses, then, contribute to reduced arterial pressure, improved baroreflex sensitivity and physical fitness of 2K1C rats.

Renovascular hypertension elevates pulmonary ventilation in rats by carotid body-dependent mechanisms.

The two kidney-one clip (2K1C) renovascular hypertension depends on the renin-angiotensin system and sympathetic overactivity. The maintenance of 2K1C hypertension also depends on inputs from the carotid bodies (CB), which when activated stimulate the respiratory activity. In the present study, we investigated the importance of CB afferent activity for the ventilatory responses in 2K1C hypertensive rats and for phrenic and hypoglossal activities in in situ preparations of normotensive rats treated with angiotensin II. Silver clips were implanted around the left renal artery of male Holtzman rats (150 g) to induce renovascular hypertension. Six weeks after clipping, hypertensive 2K1C rats showed, in conscious state, elevated resting tidal volume and minute ventilation compared with the normotensive group. 2K1C rats also presented arterial alkalosis, urinary acidification, and amplified hypoxic ventilatory response. Carotid body removal (CBR), 2 wk before the experiments (4th week after clipping), significantly reduced arterial pressure and pulmonary ventilation in 2K1C rats but not in normotensive rats. Intra-arterial administration of angiotensin II in the in situ preparation of normotensive rats increased phrenic and hypoglossal activities, responses that were also reduced after CBR. Results show that renovascular hypertensive rats exhibit increased resting ventilation that depends on CB inputs. Similarly, angiotensin II increases phrenic and hypoglossal activities in in situ preparations of normotensive rats, responses that also depend on CB inputs. Results suggest that mechanisms that depend on CB inputs in renovascular hypertensive rats or during angiotensin II administration in normotensive animals increase respiratory drive.

Exercise Training Attenuates Hypertension Through TLR4/MyD88/NF-κB Signaling in the Hypothalamic Paraventricular Nucleus.

Exercise training (ExT) is beneficial for cardiovascular health, yet the central mechanism by which aerobic ExT attenuates the hypertensive responses remains unclear. Activation of pro-inflammatory cytokines (PICs) in the hypothalamic paraventricular nucleus (PVN) is important for the sympathoexcitation and hypertensive response. We thus hypothesized that aerobic ExT can decrease the blood pressure of hypertensive rats by reducing the levels of PICs through TLR4/MyD88/NF-κB signaling within the PVN. To examine this hypothesis, two-kidney-one-clip (2K1C) renovascular hypertensive rats were assigned to two groups: sedentary or exercise training and examined for 8 weeks. At the same time, bilateral PVN infusion of vehicle or TAK242, a TLR4 inhibitor, was performed on both groups. As a result, the systolic blood pressure (SBP), renal sympathetic nerve activity (RSNA) and plasma levels of norepinephrine (NE), epinephrine (EPI) were found significantly increased in 2K1C hypertensive rats. These rats also had higher levels of Fra-like activity, NF-κB p65 activity, TLR4, MyD88, IL-1β and TNF-α in the PVN than SHAM rats. Eight weeks of ExT attenuated the RSNA and SBP, repressed the NF-κB p65 activity, and reduced the increase of plasma levels of NE, EPI, and the expression of Fra-like, TLR4, MyD88, IL-1β and TNF-α in the PVN of 2K1C rats. These findings are highly similar to the results in 2K1C rats with bilateral PVN infusions of TLR4 inhibitor (TAK242). This suggests that 8 weeks of aerobic ExT may decrease blood pressure in hypertensive rats by reducing the PICs activation through TLR4/MyD88/NF-κB signaling within the PVN, and thus delays the progression of 2K1C renovascular hypertension.

Tissue-specific transcriptional regulation of epithelial/endothelial and mesenchymal markers during renovascular hypertension.

Epithelial-to-mesenchymal transition (EMT) and endothelial-to-mesenchymal transition are processes that can occur under different biological conditions, including tissue healing due to hypertension and oxidative stress. The purpose of the present study was to evaluate the differences in gene expression of epithelial/endothelial and mesenchymal markers in different tissues. A two-kidney, one-clip (2K1C) renovascular hypertension rat model was used. Hypertension was induced by the clipping of the left renal artery; the rats were randomized into sham and 2K1C groups and monitored for up to 4 weeks. The gene expressions of E-cadherin (E-cad), N-cadherin (N-cad), α-smooth muscle actin (α-SMA), collagen I (COL1A1), collagen III (COL3A1) and hepatocyte growth factor (HGF) were determined by reverse transcription-PCR. The levels of the cytokines transforming growth factor-β1, tumor necrosis factor-α, interleukin (IL)-4, IL-6 and IL-10 were evaluated using ELISAs. The levels of thiobarbituric acid reactive substances and thiol groups were measured to evaluate oxidative stress. All analyses were performed on the liver, heart and kidneys tissues of sham and model rats. The 2K1C animals exhibited a higher systolic blood pressure, as well as cardiac hypertrophy and atrophy of the left kidney. Fibrotic alterations in the heart and kidneys were observed, as was an increase in the collagen fiber areas, and higher levels of inflammatory cytokines, which are associated with the increased expression of fibroproliferative and anti-fibrotic genes. Renovascular hypertension regulated epithelial/endothelial and mesenchymal markers, including E-cad, N-cad, α-SMA and COL1A1 in the kidneys and heart. EMT in the kidneys was mediated by an increased level of inflammatory and profibrotic cytokines, as well as by oxidative stress. The data in the present study suggested that the expression of epithelial/endothelial and mesenchymal markers are differentially regulated by hypertension in the liver, heart and kidneys.

Central Inhibition of Tumor Necrosis Factor Alpha Reduces Hypertension by Attenuating Oxidative Stress in the Rostral Ventrolateral Medulla in Renovascular Hypertensive Rats

Inflammation in the central nervous system is being considered a key player linked to neurogenic hypertension. Using combined in vivo and in vitro approaches, we investigated the effects of central inhibition of TNF-α on blood pressure, sympathetic tone, baroreflex sensitivity, and oxidative stress in the rostral ventrolateral medulla (RVLM) of rats with 2-kidney-1-clip (2K1C) renovascular hypertension. Continuous infusion of pentoxifylline, a TNF-α inhibitor, into the lateral ventricle of the brain for 14 consecutive days reduced blood pressure and improved baroreflex sensitivity in renovascular hypertensive rats. Furthermore, central TNF-α inhibition reduced sympathetic modulation and blunted the increased superoxide accumulation in the RVLM of 2K1C rats. Our findings suggest that TNF-α play an important role in the maintenance of sympathetic vasomotor tone and increased oxidative stress in the RVLM during renovascular hypertension.

A new approach to identifying hypertension-associated genes in the mesenteric artery of spontaneously hypertensive rats and stroke-prone spontaneously hypertensive rats.

Hypertension is one of the most prevalent diseases in humans who live a modern lifestyle. Alongside more effective care, clarification of the genetic background of hypertension is urgently required. Gene expression in mesenteric resistance arteries of spontaneously hypertensive rats (SHR), stroke-prone SHR (SHRSP) and two types of renal hypertensive Wistar Kyoto rats (WKY), two kidneys and one clip renal hypertensive rat (2K1C) and one kidney and one clip renal hypertensive rat (1K1C), was compared using DNA microarrays. We used a simultaneous equation and comparative selection method to identify genes associated with hypertension using the Reactome analysis tool and GenBank database. The expression of 298 genes was altered between SHR and WKY (44 upregulated and 254 downregulated), while the expression of 290 genes was altered between SHRSP and WKY (83 upregulated and 207 downregulated). For SHRSP versus SHR, the expression of 60 genes was altered (36 upregulated and 24 downregulated). Several genes expressed in SHR and SHRSP were also expressed in the renovascular hypertensive 2K1C and 1K1C rats, indicative of the existence of hyper-renin and/or hypervolemic pathophysiological changes in SHR and SHRSP. The overexpression of Kcnq1, Crlf1, Alb and Xirp1 and the inhibition of Galr2, Kcnh1, Ache, Chrm2 and Slc5a7 expression may indicate that a relationship exists between these genes and the cause and/or worsening of hypertension in SHR and SHRSP.

Enhanced angiotensin II induced sodium appetite in renovascular hypertensive rats

Renovascular hypertensive 2-kidney, 1-clip (2K1C) rats have an increased activity of the renin-angiotensin system and an initial transitory increase in daily water and NaCl intake. However, the dipsogenic and natriorexigenic responses to angiotensin II (ANG II) have not been tested yet in 2K1C rats. Therefore, in the present study, we evaluated water and 0.3 M NaCl intake induced by water deprivation (WD)-partial rehydration (PR) or intracerebroventricular (icv) ANG II in 2K1C rats. In addition, the cardiovascular changes to these treatments were also evaluated. Male Holtzman rats received a silver clip around the left renal artery to induce 2K1C renovascular hypertension. In the 5th week, a group of animals received a guide cannula in the lateral ventricle for icv injections. Daily water intake increased from the 3rd week after surgery and remained elevated until the 6th week (last recording week), whereas daily 0.3 M NaCl intake transiently increased from the 2nd to the 5th week after surgery. On the 6th week, in spite of comparable daily 0.3 M NaCl intake between 2K1C and sham rats, WD-PR and icv ANG II induced an increased 0.3 M NaCl intake in 2K1C rats. Water intake induced by WD-PR, not by icv ANG II, also increased in 2K1C rats. The increase in arterial pressure to WD-PR or icv ANG II was similar in sham and 2K1C rats. Therefore, these results suggest that 2K1C rats are more responsive to the natriorexigenic effects of ANG II, whereas other responses to ANG II are not modified.

Renovascular hypertension increases serum TNF and CX3CL1 in experimental Trypanosoma cruzi infection.

Trypanosoma cruzi triggers a progressive inflammatory response affecting cardiovascular functions in humans and experimental models. Angiotensin II, a key effector of the renin-angiotensin system, plays roles in mediating hypertension, heart failure, and inflammatory responses. T. cruzi and AngII can induce inflammatory responses by releasing inflammatory mediators. The aim of this study was to evaluate systemic AngII, tumor necrosis factor (TNF), and CX3CL1 mediators in a two-kidney one-clip (2K1C) renovascular hypertension model using Wistar rats infected with T. cruzi. Our data showed an increase in serum AngII in uninfected and T. cruzi-infected rats 1 week after 2K1C surgery compared to non-2K1C (Sham) animals. The baseline systolic blood pressure was higher in both uninfected and infected 2K1C rats. Despite no difference in circulating parasites in the acute phase of infection, elevated serum TNF and CX3CL1 were observed at 8 weeks post-infection in 2K1C rats in association with higher cardiac inflammatory infiltration. In summary, AngII-induced hypertension associated with T. cruzi infection may act synergistically to increase TNF and CX3CL1 in the 2K1C rat model, thereby intensifying cardiac inflammatory infiltration and worsening the underlying inflammation triggered by this protozoan.

Vaccarin alleviates hypertension and nephropathy in renovascular hypertensive rats

The kidney is an important organ in the regulation of blood pressure, and it is also one of the primary target organs of hypertension. Kidney damage in response to hypertension eventually leads to renal insufficiency. The authors previously demonstrated that vaccarin exhibits a protective role in endothelial injury. However, the effects of vaccarin on the two-kidney, one clip (2K1C) renovascular hypertension model and subsequent kidney injury have yet to be fully elucidated. The present study was designed to investigate the roles and mechanisms of vaccarin in attenuating hypertension and whether vaccarin had beneficial effects on kidney injury. The 2K1C rats had greater fibrosis, apoptosis, reactive oxygen species production, inflammation, angiotensin II (Ang II) and angiotensin type 1 (AT1) receptors in the right kidney compared with normotensive rats, which were alleviated by a high dose of vaccarin and captopril. Vaccarin treatment attenuated hypertension, reduced fibrosis markers, NADPH oxidase (NOX)-2, NOX-4, 3-nitrotyrosine, tumor necrosis factor-α, interleukin 1β (IL-1β), and IL-6 protein levels and altered pro-apoptotic protein levels including caspase-3, anti-apoptosis protein B cell lymphoma (Bcl)-2 and Bcl-2 associated X, apoptosis regulator in the right kidney of 2K1C rats. These findings suggest that the protective effects of vaccarin on the right kidney in renovascular hypertension are possibly due to downregulation of fibrosis, inflammatory molecules, oxidative stress, Ang II, and AT1 receptor levels.

Effect of Euterpe oleracea Mart. Seeds Extract on Chronic Ischemic Renal Injury in Renovascular Hypertensive Rats.

Previously, we have demonstrated that the seeds of Euterpe oleracia Mart. (açaí) are rich in polyphenols with antihypertensive and antioxidant properties. This study evaluated the renal protective effects of the hydroalcoholic extract obtained from the seeds of açaí (ASE) fruits in two-kidney, one-clip (2K1C) renovascular hypertension. Young male Wistar rats were used to obtain 2K1C and sham groups. Animals received ASE (200 mg/(kg·day) in drinking water) or vehicle for 40 days. We evaluated serum and urinary parameters, renal structural changes, and oxidative status. The increase in systolic blood pressure of the 2K1C group was accompanied by a decrease in left kidney volume and number of glomeruli, as well as an increase in glomerular volume and collagen deposition. ASE prevented the alterations of these parameters, except the reduced kidney volume. Serum levels of urea and creatinine and urinary protein excretion were increased in the 2K1C group and treatment with ASE improved all these functional parameters. The increased oxidative damage in the 2K1C group, assessed by lipid and protein oxidation, was prevented by ASE. The nitrite content and both expression and activity of antioxidant enzymes (superoxide dismutase-1, catalase, and glutathione peroxidase) were lower in the 2K1C group and restored by ASE. ASE substantially reduced renal injury and prevented renal dysfunction in 2K1C rats probably through its antihypertensive and antioxidant effects, providing a natural resource for treatment and prevention of renovascular hypertension-related abnormalities.