Different reactive species modulate the hypotensive effect triggered by angiotensins at CVLM of 2K1C hypertensive rats

Hypertension is associated with increased central activity of the renin-angiotensin system (RAS) and oxidative stress. Here, we evaluated whether reactive species and neurotransmitters could contribute to the hypotensive effect induced by angiotensin (Ang) II and Ang-(1-7) at the caudal ventrolateral medulla (CVLM) in renovascular hypertensive rats (2K1C). Therefore, we investigated the effect of Ang II, Ang-(1-7), and the Ang-(1-7) antagonist A-779 microinjected before and after CVLM microinjection of the nitric oxide (NO)-synthase inhibitor, (L-NAME), vitamin C (Vit C), bicuculline, or kynurenic acid in 2K1C and SHAM rats. Baseline values of the mean arterial pressure (MAP) in 2K1C rats were higher than in SHAM rats. CVLM microinjection of Ang II, Ang-(1-7), l-NAME, or bicuculline induced decreases in the MAP in SHAM and 2K1C rats. In addition, Vit C and A-779 produced decreases in the MAP only in 2K1C rats. Kynurenic acid increased the MAP in both SHAM and 2K1C rats. Only the Ang-(1-7) effect was increased by l-NAME and reduced by bicuculline in SHAM rats. L-NAME also reduced the A-779 effect in 2K1C rats. Only the Ang II effect was abolished by CVLM Vit C and enhanced by CVLM kynurenic acid in SHAM and 2K1C rats. Overall, the superoxide anion and glutamate participated in the hypotensive effect of Ang II, while NO and GABA participated in the hypotensive effect of Ang-(1-7) in CVLM. The higher hypotensive response of A-779 in the CVLM of 2K1C rats suggests that Ang-(1-7) contributes to renovascular hypertension.

Ligustrazine prevents basilar artery remodeling in two-kidney-two-clip renovascular hypertension rats via suppressing PI3K/Akt signaling

OBJECTIVE

In the present study, we used a two-kidney-two-clip (2k2c) stroke-prone renovascular hypertension rat model (RHRSP) to investigate the protective effects of ligustrazine (TMP) on cerebral arteries and to examine PI3K/Akt pathway behavior under this protection.

METHODS

The cerebral artery remodeling was induced by 2k2c-induced renovascular hypertension. Brain basilar artery tissues were isolated and their histological changes were detected through H&E and EVG staining, α-SMA IHC staining, and transmission electron microscopy at four, eight, and twelve weeks after 2k2c surgery, both with and without TMP treatment. Meanwhile, the ET-1, Ang II, and NO levels in basilar arteries and plasma were determined. Furthermore, the PTEN expression and the activation of PI3K/Akt in basilar artery tissues were detected through IHC and Western Blot. In addition, the primary basilar artery smooth muscle cells (BASMCs) were cultured and TMP protection of BASMCs stimulated with ET-1/Ang II in the presence or absence of insulin-like growth factor 1 (IGF-1) was determined.

RESULTS

TMP attenuated basilar artery remodeling, decreased ET-1 and Ang II levels and increased NO level in basilar arteries and plasma of RHRSP rats. Moreover, TMP reduced BASMCs proliferation upon ET-1/Ang II stimulation. We also found that TMP could effectively suppress the activation of PI3K/Akt in 2k2c-RHRSP rat basilar artery and ET-1/Ang II stimulated BASMCs. Most importantly, IGF-1, as an activator of PI3K/Akt, could damage the protective effect of TMP.

CONCLUSIONS

TMP exerts its protective effects and prevents basilar artery remodeling in RHRSP rats at least partly through the inhibition of PI3K/Akt pathway.

Antioxidant and antihypertensive responses to oral nitrite involves activation of the Nrf2 pathway

Impaired redox balance contributes to the cardiovascular alterations of hypertension and activation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway may counteract these alterations. While nitrite recycles back to NO and exerts antioxidant and antihypertensive effects, the mechanisms involved in these responses are not fully understood. We hypothesized that nitrite treatment of two-kidney, one-clip (2K1C) hypertensive rats activates the Nrf2 pathway, promotes the transcription of antioxidant genes, and improves the vascular redox imbalance and dysfunction in this model. Two doses of oral nitrite were studied: 15 mg/kg and the sub-antihypertensive dose of 1 mg/kg. Nitrite 15 mg/kg (but not 1 mg/kg) decreased blood pressure and increased circulating plasma nitrite and nitrate. Both doses blunted hypertension-induced increases in mesenteric artery reactive oxygen species concentrations assessed by DHE technique and restored the impaired mesenteric artery responses to acetylcholine. While 2K1C hypertension decreased nuclear Nrf2 accumulation, both doses of nitrite increased nuclear Nrf2 accumulation and mRNA expression of Nrf2-regulated genes including superoxide dismutase-1 (SOD1), catalase (CAT), glutathione peroxidase (GPX), thioredoxin-1(TRDX-1) and -2 (TRDX-2). To further confirm nitrite-mediated antioxidant effects, we measured vascular SOD and GPX activity and we found that nitrite at 1 or 15 mg/kg increased the activity of both enzymes (P < 0.05). These results suggest that activation of the Nrf2 pathway promotes antioxidant effects of nitrite, which may improve the vascular dysfunction in hypertension, even when nitrite is given at a sub-antihypertensive dose. These findings may have many clinical implications, particularly in the therapy of hypertension and other cardiovascular diseases.

A novel method for comparison of arterial remodeling in hypertension: Quantification of arterial trees and recognition of remodeling patterns on histological sections

Remodeling of spatially heterogeneous arterial trees is routinely quantified on tissue sections by averaging linear dimensions, with lack of comparison between different organs and models. The impact of experimental models or hypertension treatment modalities on organ-specific vascular remodeling remains undefined. A wide variety of arterial remodeling types has been demonstrated for hypertensive models, which include differences across organs. The purpose of this study was to reassess methods for measurement of arterial remodeling and to establish a morphometric algorithm for standard and comparable quantification of vascular remodeling in hypertension in different vascular beds. We performed a novel and comprehensive morphometric analysis of terminal arteries in the brain, heart, lung, liver, kidney, spleen, stomach, intestine, skin, skeletal muscle, and adrenal glands of control and Goldblatt hypertensive rats on routinely processed tissue sections. Mean dimensions were highly variable but grouping them into sequential 5 μm intervals permitted creation of reliable linear regression equations and complex profiles. Averaged arterial dimensions demonstrated seven remodeling patterns that were distinct from conventional inward-outward and hypertrophic-eutrophic definitions. Numerical modeling predicted at least nineteen variants of arterial spatial conformations. Recognition of remodeling variants was not possible using averaged dimensions, their ratios, or the remodeling and growth indices. To distinguish remodeling patterns, a three-dimensional modeling was established and tested. The proposed algorithm permits quantitative analysis of arterial remodeling in different organs and may be applicable for comparative studies between animal hypertensive models and human hypertension. Arterial wall tapering is the most important factor to consider in arterial morphometry, while perfusion fixation with vessel relaxation is not necessary. Terminal arteries in organs undergo the same remodeling pattern in Goldblatt rats, except for organs with hemodynamics affected by the arterial clip. The existing remodeling nomenclature should be replaced by a numerical classification applicable to any type of arterial remodeling.

Matrix metalloproteinase (MMP)-2 activation by oxidative stress decreases aortic calponin-1 levels during hypertrophic remodeling in early hypertension

Hypertension is characterized by maladaptive vascular remodeling and enhanced oxidative stress in the vascular wall. Peroxynitrite may directly activate latent matrix metalloproteinase (MMP)-2 in vascular smooth muscle cells (VSMC) by its S-glutathiolation. MMP-2 may then proteolyze calponin-1 in aortas from hypertensive animals, which stimulates VSMC proliferation and medial hypertrophy. Calponin-1 is an intracellular protein which helps to maintain VSMC in their differentiated (contractile) phenotype. The present study therefore investigated whether aortic MMP-2 activity is increased by oxidative stress in early hypertension and then contributes to hypertrophic arterial remodeling by reducing the levels of calponin-1. Male Wistar rats were submitted to the two kidney, one clip (2 K-1C) model of hypertension or sham surgery and were treated daily with tempol (18 mg/kg/day) or its vehicle (water) by gavage from the third to seventh day post-surgery. Systolic blood pressure (SBP) was daily assessed by tail-cuff plethysmography. After one week, aortas were removed to perform morphological analysis with hematoxylin and eosin staining and to analyze reactive oxygen‑nitrogen species levels by dihydroethidium and immunohistochemistry for nitrotyrosine. MMP-2 activity was analyzed by in situ and gelatin zymography and its S-glutathiolation was analyzed by Western blot for MMP-2 of anti-glutathione immunoprecipitates. Calponin-1 levels were identified in aortas by immunofluorescence. SBP increased by approximately 50 mmHg at the first week in 2 K-1C rats which was unaffected by tempol. However, tempol ameliorated the hypertension-induced increase in arterial media-to-lumen ratio and hypertrophic remodeling. Tempol also decreased hypertension-induced aortic oxidative stress and the enhanced MMP-2 activity. S-glutathiolation may be a potential mechanism by which oxidative stress activates MMP-2 in aortas of 2 K-1C rats. Furthermore, calponin-1 was decreased in aortas from 2 K-1C rats and tempol prevented this. In conclusion, oxidative stress may contribute to the increase in aortic MMP-2 activity, possibly by S-glutathiolation, and this may result in calponin-1 loss and maladaptive vascular remodeling in early hypertension.

Nitrite treatment downregulates vascular MMP-2 activity and inhibits vascular remodeling in hypertension independently of its antihypertensive effects

Hypertension is associated with cardiovascular remodeling. Given that impaired redox state activates matrix metalloproteinase (MMP)- 2 and promotes vascular remodeling, we hypothesized that nitrite treatment at a non-antihypertensive dose exerts antioxidant effects and attenuates both MMP-2 activation and vascular remodeling of hypertension. We examined the effects of oral sodium nitrite at antihypertensive (15 mg/kg) or non-antihypertensive (1 mg/kg) daily dose in hypertensive rats (two kidney, one clip; 2K1C model). Sham-operated and 2K1C hypertensive rats received vehicle or nitrite by gavage for four weeks. Systolic blood pressure decreased only in hypertensive rats treated with nitrite 15 mg/Kg/day. Both low and high nitrite doses decreased 2K1C-induced vascular remodeling assessed by measuring aortic cross-sectional area, media/lumen ratio, and number of vascular smooth muscle cells/aortic length. Both low and high nitrite doses decreased 2K1C-induced vascular oxidative stress assessed in situ with the fluorescent dye DHE and with the lucigenin chemiluminescence assay. Vascular MMP-2 expression and activity were assessed by gel zymography, Western blot, and in situ zymography increased with hypertension. While MMP-2 levels did not change in response to both doses of nitrite, both doses completely prevented hypertension-induced increases in vascular MMP activity. Moreover, incubation of aortas from hypertensive rats with nitrite at 1-20 μmol/L reduced gelatinolytic activity by 20-30%. This effect was fully inhibited by the xanthine oxidase (XOR) inhibitor febuxostat, suggesting XOR-mediated generation of nitric oxide (NO) from nitrite as a mechanism explaining the responses to nitrite. In vitro incubation of aortic extracts with nitrite 20 μmol/L did not affect MMP-2 activity. These results show that nitrite reverses the vascular structural alterations of hypertension, independently of anti-hypertensive effects. This response is mediated, at least in part, by XOR and is attributable to antioxidant effects of nitrite blunting vascular MMP-2 activation. Our findings suggest nitrite therapy to reverse structural alterations of hypertension.

Diuretic herb Gomphrena celosioides Mart. (Amaranthaceae) promotes sustained arterial pressure reduction and protection from cardiac remodeling on rats with renovascular hypertension

ETHNOPHARMACOLOGICAL RELEVANCE

Gomphrena celosioides Mart., belonging to the Amaranthaceae family, is a weed known as "perpétua," and its ethnopharmacological use is to treat of urinary tract disorders and kidney stones. Urinary tract disorders and kidney stones could include several pathological conditions such hypertension, diuretic and lithiasic problems. In the present work a model of renovascular hypertension was developed in vivo to investigate its usefulness as an antihypertensive drug.

AIM OF THE STUDY

Evaluate the effect of acute and 28 day oral administration of G. celosioides extract on systemic arterial pressure and diuresis of renovascular-hypertensive rats, as well as its effect on cardiac remodeling and vascular reactivity.

MATERIALS AND METHODS

Ethanolic extract of G. celosioides (EEGC) was used. To induce renovascular hypertension, adult male Wistar rats were submitted to Goldblatt 1K1C or 2K1C surgery. The mean arterial pressure (MAP) of 1K1C animals was directly assessed by cannulation of the carotid artery before and after intraduodenal acute administration of 30, 100 or 300 mg/kg of EEGC. For the 4-week assay, 2K1C animals received daily treatments with water (control group), 100 mg/kg EEGC or 15 mg/kg enalapril for 28 days. Diuresis and caudal blood pressure were assessed weekly, and at the 28th day of treatment, the MAP was directly quantified shortly before euthanasia. Internal organs were removed, weighed and routinely processed for histology and the left ventricle wall was measured. Blood was collected for biochemical analysis and mechanism investigation by quantification of angiotensin converting enzyme (ACE) activity and aldosterone, nitrite and thiobarbituric acid reactive substances (TBARS) concentration. The rats' mesenteric beds were isolated and cannulated to have their pressure variation assessed after crescent doses of phenylephrine (Phe), acetylcholine (ACh) and sodium nitroprusside (SNP).

RESULTS

EEGC acutely reduced MAP the dose of 100 mg/kg. In the 4-week assay, EEGC acted as diuretic after acute administration after 1, 2, 3 and 4 weeks of treatment. EEGC also acted as an antihypertensive and it showed significant difference already after 1 week (and after 3 and 4 weeks) compared to control, with its MAP close to pre-surgery values at the end of the experiment. It promoted ACE inhibition, which led to lower aldosterone levels. The lower TBARS and higher nitrite concentration found in the EEGC group suggest antioxidant activity and NO maintenance. Moreover, EEGC counteracted the impairment of vascular reactivity induced by renovascular hypertension. The extract group presented thinner left ventricle wall compared to the control, meaning reduced hypertension-induced cardiac remodeling.

CONCLUSIONS

The G. celosioides diuretic effect is maintained on renovascular hypertensive rats and can reduce the blood pressure after the first week of treatment by inhibiting ACE and these effects are longstanding and strong enough to promote protection against cardiac remodeling. Therefore, it shows potential as an antihypertensive drug.

Imaging studies in pediatric fibromuscular dysplasia (FMD): a single-center experience

BACKGROUND

Fibromuscular dysplasia (FMD) is a non-inflammatory vascular disease that in children unlike in adults shows no sex predilection. FMD is often underdiagnosed, and its pathophysiology is unclear. Delayed diagnosis may lead to refractory hypertension and decreases the chance of successful treatment. Doppler ultrasound (US), magnetic resonance angiography (MRA), computed tomography angiography (CTA), and catheter-based angiography (angiography) are currently used to help make a clinicoradiological diagnosis of FMD. The main aim of the study was to compare the efficacy of imaging modalities which can allow for earlier and improved detection. Furthermore, an anatomical mapping of the location of lesions can help determine the best treatment modalities.

METHODS

All patients with non-syndromic non-inflammatory renovascular hypertension were recruited from the Nephrology Department at the Children's Hospital of Philadelphia (CHOP) and enrolled in the U.S. FMD Registry maintained at the University of Michigan. Clinical presentation and imaging findings on US, CT, and MRI of children diagnosed with FMD were evaluated.

RESULTS

Mean age at diagnosis was 7 ± 4.9 years (4 months-17 years). Family history of hypertension (HTN) (52%), FMD (8.7%), Caucasian (60%), headache (48%), and HTN (80%) were the most prevalent symptom and sign at presentation. Bruits were 100% specific for renal artery stenosis (RAS) diagnosis but were heard in the minority of patients (3 patients, 12%). FMD was mainly unifocal within a single site (68%) or multiple sites (28%) and involved the main or first order renal branch in about 68% of children. Isolated distal lesions beyond the second order branches were found in about 25% of children. US imaging was significantly less sensitive than angiography (28%, p = 0.003). MRA had a better sensitivity (62.5%, p = 0.3) than US. Overall, CTA had the best sensitivity (84.2%, p = 0.4) compared to angiography; however, only angiography showed distal vessel disease.

CONCLUSIONS

Limitations of the study include the sample size and biases-only patients diagnosed with FMD were included in this study and most patients were referred to a pediatric nephrologist for unexplained hypertension. Angiography should be performed as part of the initial work-up of any child suspected of having renovascular FMD, regardless of the findings seen on US, MRA, or CTA.

Matrix Metalloproteinase-2 Activity is Associated with Divergent Regulation of Calponin-1 in Conductance and Resistance Arteries in Hypertension-induced Early Vascular Dysfunction and Remodelling

Matrix metalloproteinase (MMP)-2 participates in hypertension-induced maladaptive vascular remodelling by degrading extra- and intracellular proteins. The consequent extracellular matrix rearrangement and phenotype switch of vascular smooth muscle cells (VSMCs) lead to increased cellular migration and proliferation. As calponin-1 degradation by MMP-2 may lead to VSMC proliferation during hypertension, the hypothesis of this study is that increased MMP-2 activity contributes to early hypertension-induced maladaptive remodelling in conductance and resistance arteries via regulation of calponin-1. The main objective was to analyse whether MMP-2 exerts similar effects on the structure and function of the resistance and conductance arteries during early hypertension. Two-kidney, one-clip (2K-1C) hypertensive male rats and corresponding controls were treated with doxycycline (30 mg/kg/day) or water until reaching one week of hypertension. Systolic blood pressure was increased in 2K-1C rats, and doxycycline did not reduce it. Aortas and mesenteric arteries were analysed. MMP-2 activity and expression were increased in both arteries, and doxycycline reduced it. Significant hypertrophic remodelling and VSMC proliferation were observed in aortas but not in mesenteric arteries of 2K-1C rats. The contractility of mesenteric arteries to phenylephrine was increased in 2K-1C rats, and doxycycline prevented this alteration. The potency of phenylephrine to contract aortas of 2K-1C rats was increased, and doxycycline decreased it. Whereas calponin-1 expression was increased in 2K-1C mesenteric arteries, calponin-1 was reduced in aortas. Doxycycline treatment reverted changes in calponin-1 expression. MMP-2 contributes to hypertrophic remodelling in aortas by decreasing calponin-1 levels, which may result in VSMC proliferation. On the other hand, MMP-2-dependent increased calponin-1 in mesenteric arteries may contribute to vascular hypercontractility in 2K-1C rats. Divergent regulation of calponin-1 by MMP-2 may be an important mechanism that leads to maladaptive vascular effects in hypertension.

Elevated urinary podocyte-derived extracellular microvesicles in renovascular hypertensive patients

BACKGROUND

An increased number of podocyte-derived extracellular vesicles (pEVs) may reflect podocyte injury in renal disease. Elevated glomerular pressure and other insults may injure podocytes, yet it remains unclear whether the numbers of pEVs are altered in hypertensive patients. We tested the hypothesis that urinary pEV levels would be elevated in patients with renovascular hypertension (RVH) compared with essential hypertension (EH) or healthy volunteers (HVs).

METHODS

We prospectively enrolled patients with EH ( n = 30) or RVH ( n = 31) to study renal blood flow (RBF) and cortical perfusion using multidetector computed tomography under controlled condition (regulated sodium intake and renin-angiotensin blockade). After isolation from urine samples, pEVs (nephrin and podocalyxin positive) were characterized by flow cytometry. Fourteen RVH patients were studied again 3 months after stenting or continued medical therapy. HVs ( n = 15) served as controls.

RESULTS

The fraction of pEV among urinary EVs was elevated in RVH compared with HVs and EH (11.4 ± 6.4, 6.8 ± 3.4 and 6.3 ± 3.7%, respectively; P < 0.001) and remained unchanged after 3 additional months of therapy and after controlling for clinical parameters. However, eGFR- and age-adjusted pEV levels did not correlate with any clinical or renal parameters.

CONCLUSIONS

In hypertensive patients under controlled conditions, urinary pEV levels are elevated in patients with RVH and low eGFR compared with patients with EH and relatively preserved renal function. These pEVs may reflect podocyte injury secondary to kidney damage, and their levels might represent a novel therapeutic target.

Decreased immunoreactivity of visfatin in the pancreas and liver of rats with renovascular hypertension

Hypertension is one of the major endocrine and metabolic disorders, in which visfatin plays a significant role. The objective of this study was to evaluate the immunoreactivity of visfatin in pancreas and liver of “two kidney, one clip” (2K1C) renovascular hypertension model in rats. The studies were carried out on the pancreas and liver of rats. After a 6-week period of the renal artery clipping procedure, 2K1C rats developed a stable hypertension. Paraffin sections were stained with hematoxylin and eosin (for general histological examination) and processed for immunolocalization of visfatin. The intensity of immunohistochemical reaction was measured using Nikon NIS-Elements Advanced Research software. The hypertension significantly weakened the immunohistochemical reaction exhibiting visfatin in the pancreas and liver of hypertensive rats, compared to control animals. The changes induced by hypertension in the visfatin-containing cells in the pancreas and liver of the rats are discussed and needs further study.

Hypercholesterolemia Impairs Nonstenotic Kidney Outcomes After Reversal of Experimental Renovascular Hypertension

BACKGROUND

Revascularization of a stenotic renal artery improves kidney function only in select patients with renovascular hypertension (HT) secondary to atherosclerosis. However, the effects of reversal of renovascular HT (RRHT) on the nonstenotic kidney are unclear. We hypothesized that concurrent hypercholesterolemia (HC) attenuates nonstenotic kidney recovery.

METHODS

Female domestic pigs were randomized as Normal, renovascular HT, HT+RRHT, HTC (renovascular HT and HC), and HTC+RHT (n = 7 each). RRHT or sham was performed after 6 weeks of HT. Nonstenotic renal blood flow, glomerular filtration rate, and injurious pathways were studied 4 weeks later.

RESULTS

Mean arterial pressure increased similarly in HT and HTC and decreased after RRHT. Oxidative stress increased in HT and HTC kidneys, and decreased in HT+RRHT, but remained elevated in HTC+RRHT. Renal interstitial fibrosis, glomerulosclerosis, and tubular injury were all attenuated in HT+RRHT, but not HTC+RRHT. Endothelin-1 signaling and PGF2α isoprostane levels were elevated in both HTC and HTC+RRHT pigs.

CONCLUSIONS

RRHT reverses nonstenotic kidney injury in experimental renovascular HT, but concurrent HC blunts regression of kidney injury, possibly due to predominant vasoconstrictors and oxidative stress. These findings reinforce the contribution of the nonstenotic kidney and of prevailing cardiovascular risk factors to irreversibility of kidney dysfunction after revascularization.

Prior renovascular hypertension does not predispose to atherosclerosis in mice

BACKGROUND

Hypertension is a major risk factor for development of atherosclerotic cardiovascular disease (ASCVD). Although lowering blood pressure with antihypertensive drugs reduces the increased risk of ASCVD, residual increased risk still remains, suggesting that hypertension may cause chronic changes that promote atherosclerosis. Thus, we tested the hypothesis that hypertension increases the susceptibility to atherosclerosis in mice even after a period of re-established normotension.

METHODS

We used the 2-kidney, 1-clip (2K1C) technique to induce angiotensin-driven renovascular hypertension, and overexpression of the proprotein convertase subtilisin/kexin type 9 (PCSK9) gene to cause severe hypercholesterolemia and atherosclerosis.

RESULTS

First, we performed 2K1C (n = 8) or sham surgery (n = 9) in PCSK9 transgenic mice before they were fed a high fat diet for 14 weeks. As expected, 2K1C did not affect cholesterol levels, but induced cardiac hypertrophy and significantly increased the atherosclerotic lesion area compared to sham mice (1.8 fold, p < 0.01). Next, we performed 2K1C (n = 13) or sham surgery (n = 14) in wild-type mice but removed the clipped/sham-operated kidney after 10 weeks to eliminate hypertension, and subsequently induced hypercholesterolemia by way of adeno-associated virus-mediated hepatic gene transfer of PCSK9 combined with high-fat diet. After 14 weeks of hypercholesterolemia, atherosclerotic lesion areas were not significantly different in mice with or without prior 2K1C hypertension (0.95 fold, p = 0.35).

CONCLUSION

Renovascular hypertension in mice does not induce pro-atherogenic changes that persist beyond the hypertensive phase. These results indicate that hypertension only promotes atherogenesis when coinciding temporally with hypercholesterolemia.

Aortic Intimal Sarcoma Contributes to Atherosclerotic Renovascular Hypertension: An Autopsy Case Report and Review of the Literature

An autopsy of a 70-year-old man with multiple bone metastases from a malignancy of unknown origin (MUO) and renovascular hypertension revealed an aortic intimal sarcoma (AIS) in the right renal artery accompanied by atherosclerotic changes. AIS appeared as aggregated mutton fat-like translucent particles arising from the intima of the branching portion of the right renal artery and was composed of undifferentiated, fine spindle cells with thicket-like proliferation. AIS was confirmed by immunohistopathology, showing the loss of the lumen lined by CD31-positive endothelium and the expression of CD31, keratin, and vimentin in the viable part of the tumor. In patients with MUO presenting with both bone metastases and an acute or sub-acute onset of renovascular hypertension, AIS in the renal artery may be responsible.

Spontaneous white matter lesion in brain of stroke-prone renovascular hypertensive rats: a study from MRI, pathology and behavior

Hypertension is considered one of the most important controllable risk factors for white matter lesion (WML). Our previous work found that stroke-prone renovascular hypertensive rats (RHRSP) displayed a high rate of WML. This study aimed to investigate the WML in RHRSP from MRI, pathology and behavior. RHRSP model was established by two-kidney, two-clipmethod and kept for 20 weeks. WML was decteted by magnetic resonance imaging (MRI) and loyez staining. Cognition was tested by morris water maze (MWM). Vascular changes were observed by HE staining on brain and carotid sections. Ultrastucture of blood brain barrier (BBB) were observed by transmission electron microscope. Immunofluorescence was used to detect albumin leakage and cell proliferation. T(2)-weighted MRI scans of RHRSP displayed diffuse, confluent white-matter hyperintensities. Pathological examination of the same rat showed marked vacuoles, disappearence of myelin and nerve fibers in white matter, supporting the neuroimaging findings. Spatial learning and memory impairment were observed in RHRSP. The small arteries in brain exhibited fibrinoid necrosis, hyalinosis and vascular remodeling. BBB disruption and plasma albumin leakage into vascular wall was observed in RHRSP. Increased cell proliferation in subventricular zone was seen in RHRSP. RHRSP demonstrated spontaneous WML and cognitive impairment. Hypertensive small vessel lesions and BBB disruption might paly causative factors for the onset and development of WML. The characteristic features of WML in RHRSP suggested it a valid animal model for WML.

Atherosclerotic Plaque Destabilization in Mice: A Comparative Study

Atherosclerosis-associated diseases are the main cause of mortality and morbidity in western societies. The progression of atherosclerosis is a dynamic process evolving from early to advanced lesions that may become rupture-prone vulnerable plaques. Acute coronary syndromes are the clinical manifestation of life-threatening thrombotic events associated with high-risk vulnerable plaques. Hyperlipidemic mouse models have been extensively used in studying the mechanisms controlling initiation and progression of atherosclerosis. However, the understanding of mechanisms leading to atherosclerotic plaque destabilization has been hampered by the lack of proper animal models mimicking this process. Although various mouse models generate atherosclerotic plaques with histological features of human advanced lesions, a consensus model to study atherosclerotic plaque destabilization is still lacking. Hence, we studied the degree and features of plaque vulnerability in different mouse models of atherosclerotic plaque destabilization and find that the model based on the placement of a shear stress modifier in combination with hypercholesterolemia represent with high incidence the most human like lesions compared to the other models.

Gastric S-nitrosothiol formation drives the antihypertensive effects of oral sodium nitrite and nitrate in a rat model of renovascular hypertension

Many effects of nitrite and nitrate are attributed to increased circulating concentrations of nitrite, ultimately converted into nitric oxide (NO(•)) in the circulation or in tissues by mechanisms associated with nitrite reductase activity. However, nitrite generates NO(•) , nitrous anhydride, and other nitrosating species at low pH, and these reactions promote S-nitrosothiol formation when nitrites are in the stomach. We hypothesized that the antihypertensive effects of orally administered nitrite or nitrate involve the formation of S-nitrosothiols, and that those effects depend on gastric pH. The chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats treated with omeprazole (or vehicle). Oral nitrite lowered blood pressure and increased plasma S-nitrosothiol concentrations independently of circulating nitrite levels. Increasing gastric pH with omeprazole did not affect the increases in plasma nitrite and nitrate levels found after treatment with nitrite. However, treatment with omeprazole severely attenuated the increases in plasma S-nitrosothiol concentrations and completely blunted the antihypertensive effects of nitrite. Confirming these findings, very similar results were found with oral nitrate. To further confirm the role of gastric S-nitrosothiol formation, we studied the effects of oral nitrite in hypertensive rats treated with the glutathione synthase inhibitor buthionine sulfoximine (BSO) to induce partial thiol depletion. BSO treatment attenuated the increases in S-nitrosothiol concentrations and antihypertensive effects of oral nitrite. These data show that gastric S-nitrosothiol formation drives the antihypertensive effects of oral nitrite or nitrate and has major implications, particularly to patients taking proton pump inhibitors.

Venthamarai chooranam, a polyherbal Siddha medicine, alleviates hypertension via AT₁R and eNOS signaling pathway in 2K1C hypertensive rats

The present study was aimed to scientifically demonstrate the anti-hypertensive action of Venthamarai chooranam (VMC) in renal hypertensive rats. Two Kidney One Clip (2K1C) Goldblatt model was adopted to induce hypertension in rats. Male Sprague Dawley rats (270-320 g) were randomized into sham (n = 6), vehicle-treated 2K1C (n = 9) and VMC-treated 2K1C (400 mg/kg, p.o; n = 8) and monitored for nine weeks. Systolic blood pressure (SBP), plasma nitrate/nitrite, carotid endothelial nitric oxide synthetase (eNOS), renal angiotensin type 1 receptor (AT₁R), angiotensin type 2 receptor (AT₂R), TNFα, IL-6, thioredoxin 1 (TRX1), and thioredoxin reductase 1 (TRXR1) mRNA expressions were studied. VMC upregulated eNOS expression which in turn improved plasma nitric oxide and decreased SBP in hypertensive rats. It down-regulated AT₁R and simultaneously upregulated AT₂R expression in comparison to vehicle-treated 2K1C rats. Further, renal TNFα and IL-6 expressions were down-regulated while TRX1 and TRXR1 were upregulated by VMC. VMC potentially interacts with renin-angiotensin components and endothelial functions, and thereby exerts its antihypertensive action. This is the first study to demonstrate the mechanism of anti-hypertensive action of VMC in an animal model of renovascular hypertension.

Ultrastructural pathological features of unilateral renal artery stenosis in the rats

Renal artery stenosis (RAS) is one of the main reasons of renovascular hypertension and its pathogenesis remains unclear. In this study, we aimed to investigate histopathological characteristics in a rat model of RAS. Sprague-Dawley (SD) male rats were randomly divided into unilateral RAS group (Model group, n=30) and Sham group (n=30). The left renal artery was clamped with miniature silver clip for the rats in RAS group, while it was exposed but not clamped for the rats in Sham group. After the surgery, the rats were randomly divided into ten subgroups based on the time after surgery (n=3). Blood pressure, urinary albumin/creatinine ratio, and serum albumin and creatinine levels were measured. The kidneys were dissected for histological and electron microscopy analysis. The results showed that systolic blood pressure was significantly higher since 4 weeks after surgery compared to before surgery. There were no significant differences in urinary albumin/creatinine ratio as well as serum albumin and creatinine levels in Model and Sham groups. During the early acute renal ischemia the stenotic kidney exhibited acute tubular injury, podocyte injury and some crescent formation, and the main components of crescent are podocytes. Although renal tubules and vascular lesions gradually recover and crescent disappears, segmental lesions of podocyte appear in the late stage of RAS. These data reveal ultrastructural pathological changes during RAS, and suggest the role of podocyte lesions in chronic renal ischemia.

Effects of emodin and irbesartan on ventricular fibrosis in Goldblatt hypertensive rats

Left ventricular (LV) fibrosis is one of the most prominent pathophysiological results of hypertension. We initiated this study to investigate the effects and mechanisms of emodin and its combination with irbesartan on LV fibrosis in Goldblatt (2K1C) hypertensive rats. Goldblatt hypertension rats were prepared by two kidney one clip (2K1C) operations and then treated with either emodin, irbesartan or their combination. As a result, the systolic blood pressure (SBP) and the left ventricular mass index (LVMI) increased significantly (P < or = 0.05) in all 2K1C rats. After drugs treatment, irbesartan and the drug combination remarkably decreased SBP, LVMI, contents of angiotensinII (AngII), hydroxyproline and collagen, the mRNA and protein expression levels of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) (P < or = 0.05). As for the emodin, LVMI, contents of hydroxyproline and collagen, and MMP-2 and TIMP-2 expression were found to decrease significantly; however, the SBP and AngII contents stayed stable within certain extent. Therefore, emodin, irbesartan or two drugs together can potentially inhibit the ventricular fibrosis in Goldblatt hypertensive rats by reducing MMP-2 and TIMP-2 expression. Furthermore, the combination of these two drugs may provide a better anti-fibrosis effect than the single application.

Nebivolol attenuates prooxidant and profibrotic mechanisms involving TGF-β and MMPs, and decreases vascular remodeling in renovascular hypertension

Nebivolol and metoprolol are β1-adrenergic receptor blockers with different properties. We hypothesized that nebivolol, but not metoprolol, could attenuate prooxidant and profibrotic mechanisms of hypertension and therefore protect against the vascular remodeling associated with hypertension. Hypertension was induced in male Wistar rats by clipping the left renal artery. Six weeks after surgery, hypertensive and sham rats were treated with nebivolol (10 mg kg(-1) day(-1)) or metoprolol (20 mg kg(-1) day(-1)) for 4 weeks. Systolic blood pressure was monitored weekly. Morphologic changes in the aortic wall were studied in hematoxylin/eosin and picrosirius red sections. Aortic NAD(P)H activity and superoxide production were evaluated by luminescence and dihydroethidium, respectively, and TBARS levels were measured in plasma. Aortic nitrotyrosine staining was evaluated to assess peroxynitrite formation. TGF-β levels and p-ERK 1/2 expression were determined by immunofluorescence and Western blotting, respectively. Matrix metalloproteinase (MMP) activity and expression were determined by in situ zymography, gel zymography, Western blotting, and immunofluorescence, and TIMP-1 was assessed by immunohistochemistry. Both β1-receptor antagonists exerted very similar antihypertensive effects. However, while metoprolol had no significant effects, nebivolol significantly attenuated vascular remodeling and collagen deposition associated with hypertension. Moreover, nebivolol, but not metoprolol, attenuated hypertension-induced increases in aortic NAD(P)H oxidase activity, superoxide production, TBARS concentrations, nitrotyrosine levels, TGF-β upregulation, and MMP-2 and -9 expression/activity. No effects on p-ERK 1/2 and TIMP-1 expression were found. These results show for the first time that nebivolol, but not metoprolol, attenuates prooxidant and profibrotic mechanisms involving TGF-β and MMP-2 and MMP-9, which promote vascular remodeling in hypertension.

Mesenchymal stem cells (MSC) prevented the progression of renovascular hypertension, improved renal function and architecture

Renovascular hypertension induced by 2 Kidney-1 Clip (2K-1C) is a renin-angiotensin-system (RAS)-dependent model, leading to renal vascular rarefaction and renal failure. RAS inhibitors are not able to reduce arterial pressure (AP) and/or preserve the renal function, and thus, alternative therapies are needed. Three weeks after left renal artery occlusion, fluorescently tagged mesenchymal stem cells (MSC) (2×10⁵ cells/animal) were injected weekly into the tail vein in 2K-1C hypertensive rats. Flow cytometry showed labeled MSC in the cortex and medulla of the clipped kidney. MSC prevented a further increase in the AP, significantly reduced proteinuria and decreased sympathetic hyperactivity in 2K-1C rats. Renal function parameters were unchanged, except for an increase in urinary volume observed in 2K-1C rats, which was not corrected by MSC. The treatment improved the morphology and decreased the fibrotic areas in the clipped kidney and also significantly reduced renal vascular rarefaction typical of 2K-1C model. Expression levels of IL-1β, TNF-α angiotensinogen, ACE, and Ang II receptor AT₁ were elevated, whereas AT₂ levels were decreased in the medulla of the clipped kidney. MSC normalized these expression levels. In conclusion, MSC therapy in the 2K-1C model (i) prevented the progressive increase of AP, (ii) improved renal morphology and microvascular rarefaction, (iii) reduced fibrosis, proteinuria and inflammatory cytokines, (iv) suppressed the intrarenal RAS, iv) decreased sympathetic hyperactivity in anesthetized animals and v) MSC were detected at the CNS suggesting that the cells crossed the blood-brain barrier. This therapy may be a promising strategy to treat renovascular hypertension and its renal consequences in the near future.

Differential expression of Nad(P)H oxidase isoforms and the effects of atorvastatin on cardiac remodeling in two-kidney two-clip hypertensive rats

The NADPH oxidases (Noxes) are a family of ROS (reactive oxygen species)-generating enzymes which play a critical role in the development of cardiac remodeling associated with heart failure. The Noxes of their catalytic isoforms include multiple homologues in cardiovascular cells with wide range tissue distribution. It is still unclear which Noxes represent the major enzymatic source of ROS in the heart and play a predominant role in cardiac hypertrophy. In this study we investigated the differential expression changes of NAD(P)H oxidase P47phox isoform and Nox homologues in left ventricle and the effects of atorvastatin on cardiac remodeling in two-kidney two-clip(2K2C) hypertensive rats. The mRNA and protein expression of Nox2, Nox4 and P47phox showed a sustained increase at 4, 8, 12 weeks after surgery in 2K2C rats. Administration of atorvastatin attenuated cardiac dysfunction, hypertrophy and fibrosis of 2K2C rats. However, atorvastatin treatment had no effects on BP regulation. Further studies revealed that atorvastatin inhibited the increased expression of Nox2, Nox4, P47phox as well as 02"- production in 2K2C hypertensive rats. These findings indicate that Nox2, Nox4 and P47phox play a crucial role in the development of cardiac remodeling in the 2K2C hypertensive rats. Atorvastatin, independent of BP control, exerts anti-remodeling effects partially by inhibition of NAD(P)H oxidase-mediated cardiac oxidative stress.

[Effect of losartan on the protection of the kidney and PRCP-kallikrein axis of the two-kidney, one-clipped renovascular hypertensive rats]

To investigate the effect of losartan on the axis of prolylcarboxypeptidase (PRCP)--kallikrein of the two-kidney, one-clipped (2K1C) hypertensives rats, and explore the novel protection mechanism of losartan on the kidney. Sprague-Dawley (SD) rats were used to develop the 2K1C hypertensive rats. Then, the rats were treated with prazosin (5 mg x kg(-1) x d(-1)) or losartan (5, 15 and 45 mg x kg(-1) x d(-1)) or vehicle, separately. At the same time, the blood pressures were observed. After treated for four weeks, the ratio of right kidney weight and body weight, the change of glomerular morphology, and K+, Na+, creatinine and blood urea nitrogen (BUN) of the serum were used for evaluation of kidney. The expressions of PRCP mRNA in the kidneys were determined by RT-PCR. The protein levels of PRCP, tissue kallikrein, plasma kallikrein, TGF-beta1 in kidney or plasma were measured by Western blotting. Results showed that the changes of body weight and kidney weight ratio, glomerular fibrosis degree and the biochemistrical index of serum induced by hypertension were relieved when the hypertensive rats treated with losartan for four weeks. Meanwhile, treatment of losartan also significantly decreased expression of TGF-beta1 and increased expressions of PRCP, plasma kallikrein and tissue kallikrein. The protective effects of losartan on the kidney of 2K1C hypertensive rats are activation of the axis of PRCP-kallikrein and reducing the expression of TGF-beta1.

Angiotensin-(1-7) in paraventricular nucleus modulates sympathetic activity and cardiac sympathetic afferent reflex in renovascular hypertensive rats

Background

Excessive sympathetic activity contributes to the pathogenesis and progression of hypertension. Enhanced cardiac sympathetic afferent reflex (CSAR) is involved in sympathetic activation. This study was designed to determine the roles of angiotensin (Ang)-(1–7) in paraventricular nucleus (PVN) in modulating sympathetic activity and CSAR and its signal pathway in renovascular hypertension.

Methodology/Principal Findings

Renovascular hypertension was induced with two-kidney, one-clip method. Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded in sinoaortic-denervated and cervical-vagotomized rats with anesthesia. CSAR was evaluated with the RSNA and MAP responses to epicardial application of capsaicin. PVN microinjection of Ang-(1–7) and cAMP analogue db-cAMP caused greater increases in RSNA and MAP, and enhancement in CSAR in hypertensive rats than in sham-operated rats, while Mas receptor antagonist A-779 produced opposite effects. There was no significant difference in the angiotensin-converting enzyme 2 (ACE2) activity and Ang-(1–7) level in the PVN between sham-operated rats and hypertensive rats, but the Mas receptor protein expression in the PVN was increased in hypertensive rats. The effects of Ang-(1–7) were abolished by A-779, adenylyl cyclase inhibitor SQ22536 or protein kinase A (PKA) inhibitor Rp-cAMP. SQ22536 or Rp-cAMP reduced RSNA and MAP in hypertensive rats, and attenuated the CSAR in both sham-operated and hypertensive rats.

Conclusions

Ang-(1–7) in the PVN increases RSNA and MAP and enhances the CSAR, which is mediated by Mas receptors. Endogenous Ang-(1–7) and Mas receptors contribute to the enhanced sympathetic outflow and CSAR in renovascular hypertension. A cAMP-PKA pathway is involved in the effects of Ang-(1–7) in the PVN.

[Role of valsartan on myocardial Calpain I, calcineurin and Ca/calmodulin-dependent protein kinase IIδ expression of renovascular hypertensive rats]

OBJECTIVE

To determine the protein expression of Calpain I, mRNA and protein expressions and activity of calcineurin, and the alternative splicing of Ca/calmodulin-dependent protein kinase II (CaMKII) δ in the hypertrophic heart, and to investigate the effect of angiotensin II type 1 receptor blocker valsartan (Val) on cardiac hypertrophy and the level of Calpain I, calcineurin and CaMKIIδ in renovascular hypertensive rats model.

METHODS

Rats were randomly divided into sham-operated control (n=8), hypertension (n=8) and hypertension plus Val (n=8, 30 mg×kg(-1)×(-1)). The renovascular hypertension was induced by two kidney-one clip methods in rats. The ratio of left ventricular weight to body weight was measured, the mRNA expression of calcineurin and alternative splicing of CaMKIIδ were determined by RT-PCR, the protein expression of Calpain I and calcineurin were measured by Western blot and the activity of calcineurin activity was assayed by a specialized kit.

RESULTS

Eight weeks after procedure, hypertension rats developed significantly cardiac hypertrophy, and the protein expression of Calpain I, mRNA and protein expression and the activity of calcineurin were significantly increased compared sham-operated control rats (all P<0.01), the mRNA expression of CaMKIIδA and B increased, CaMKIIδC mRNA decreased (P<0.01). Treatment with valsartan effectively attenuated cardiac hypertrophy and reversed hypertension induced changes on myocardial Calpain I, calcineurin and CaMKIIδ.

CONCLUSION

Valsartan attenuates cardiac hypertrophy in renovascular hypertensive rats, possibly through inhibiting Calpain I, calcineurin and CaMKIIδ signaling pathways.

Time course involvement of matrix metalloproteinases in the vascular alterations of renovascular hypertension

Increased vascular matrix metalloproteinases (MMPs) levels play a role in late phases of hypertensive vascular remodeling. However, no previous study has examined the time course of MMPs in the various phases of two-kidney, one-clip hypertension (2K1C). We examined structural vascular changes, collagen and elastin content, vascular oxidative stress, and MMPs levels/activities during the development of 2K1C hypertension. Plasma angiotensin converting enzyme (ACE) activity was measured to assess renin-angiotensin system activation. Sham or 2K1C hypertensive rats were studied after 2, 4, 6, and 10weeks of hypertension. Systolic blood pressure (SBP) was monitored weekly. Morphometry of structural changes in the aortic wall was studied in hematoxylin/eosin, orcein and picrosirius red sections. Aortic NADPH activity and superoxide production was evaluated. Aortic gelatinolytic activity was determined by in situ zymography, and MMP-2, MMP-14, and tissue inhibitor of MMPs (TIMP)-2 levels were determined by gelatin zymography, immunofluorescence and immunohistochemistry. 2K1C hypertension was associated with increased ACE activity, which decreased to normal after 10 weeks. We found increased aortic collagen and elastin content in the early phase of hypertension, which were associated with vascular hypertrophy, increased vascular MMP-2 and MMP-14 (but not TIMP-2) levels, and increased gelatinolytic activity, possibly as a result of increased vascular NADPH oxidase activity and oxidative stress. These results indicate that vascular remodeling of renovascular hypertension is an early process associated with early increases in MMPs activities, enhanced matrix deposition and oxidative stress. Using antioxidants or MMPs inhibitors in the early phase of hypertension may prevent the vascular alterations of hypertension.

[Anti-lipotoxic action of sesamin on renovascular hypertensive rats fed with a high-fat, high-sucrose diet]

This study is to observe anti-lipotoxic effect of sesamin on renovascular hypertensive rats fed with a high-fat, high-sucrose diet. Thirty-four complex model rats were induced by two-kidney, one-clip method and on high-fat and refined-carbohydrate diet for thirteen weeks. From the fifth week, intragastric administration of sesamin (120, 60 and 30 mg x kg(-1) x d(-1)) lasted for eight weeks. Blood pressure (BP), blood fat (BF), blood glucose (BG), free fatty acids (FFA), insulin (Ins), tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 were determined. Pathological changes of pancreas, perirenal fat and liver were semiquantitatively analyzed. In sesamin (120 and 60 mg x kg(-1) x d(-1)) group, it was found that there were decrease of levels of BP, BF, BG, TNF-alpha, IL-6 and FFA, improvement of insulin resistance and glucose tolerance, alleviation of body weight, humid weight of fat, liver and pancreas and their organ index, and reduction of islet cell hyperplasia and amount of lipid droplet vacuoles in lipocyte and hepatocyte. It is implied that sesamin had anti-lipotoxic effect and its mechanism may be closely associated with the amelioration of insulin resistance via reducing lipidoses in hepatocyte and inflammatory adipokines such as TNF-alpha and IL-6.

[Renal arteries stenting using distal antiembolic devices]

Endovascular treatment of vasorenal hypertension (VRH) constitutes the operation of choice in selected groups of patients. In the Centre there was conducted a renal arteries (RA) stenting, using antiembolic devices in 6 patients (4 men and 2 women). There were applied distal filters Accunet (Abbot Vascular, USA) 12 mm in length with diameter of a cell 150 mcm. The devices application, having a net structure, is possible in optimal anatomy of artery (rectangular branching), significant stenosis of RA, primarily bad renal function, a presence of anatomically loose plaque in RA, atherosclerotic ulceration of the abdominal aorta wall. There are limitations of their application: an ischemia while performing of the procedure, complexity of the stenotic region visualization, as well as a control of a precise delivering and implantation of a stent-system and a possibility of the embolism occurrence after extraction of occluding balloon.

Tanshinone IIA prevents cardiac remodeling through attenuating NAD (P)H oxidase-derived reactive oxygen species production in hypertensive rats

Tanshinone IIA is one of major constituents of Salvia miltiorrhiza Bunge known as Danshen. Our and others' studies have shown that Tan IIA could protect cardimyocyte against apoptosis; however the effect of Tan IIA on cardiac remodeling disease is still unknown. In this study, we investigated the effects of Tan IIA on cardiac hypertrophy and fibrosis in two-kidney, two-clip (2K2C) hypertensive rats and by which, if any, mechanisms. Administration of 2K2C hypertensive rats with Tan IIA attenuated cardiac dysfunction and fibrosis. However Tan IIA treatment had no effects on BP control. Further studies revealed that Tan IIA inhibited the increased NAD(P)H oxidase activity and expression as well as O2*- production in 2K2C hypertensive rats. Our results indicated that Tan IIA significantly improved cardiac function and attenuated fibrosis in 2K2C hypertensive rats. The protective action of Tan IIA is likely mediated by its antioxidant effect, independent of BP control, partially via inhibiting NADPH oxidase.

Connections between renovascular hypertension and nephrectomy

Renovascular hypertension (RVH) is very often an under-diagnosed condition, being discovered incidentally, at a routine medical check-up or during a medical examination for another disease. A number of 217 biological samples (kidney and renal pelvis) resulting from the nephrectomies performed during the period 2008-2009 in the Urology Clinic of Oradea County Hospital have been taken into study. These samples were processed in the Pathology Laboratory of the same hospital. The distribution of nephrectomies according to the urological diagnosis has shown that 38.2% of the patients underwent surgical procedure for renal parenchymal malignant tumor (Grawitz tumor). Out of the 83 nephrectomies caused by renal tumor, in eight cases, benign and malignant angiosclerosis histological changes were seen, which demonstrates a long evolution of hypertension. Its clinical symptoms were masked by those triggered by the tumor. Histopathological changes of benign nephroangiosclerosis with arteriolar vasospasm associated with edema of the wall and/or hypertrophy of the intima with the formation of hyaline deposits were found in three nephrectomies due to hydronephrosis. The pathological study carried on samples obtained from nephrectomies showed that the symptoms of RVH are hidden or accompanied by clinical manifestations of a surgical disease. The percentage of 8.8% of the patients that had histopathologic changes or malignant of benign nephroangio-sclerosis and suffered nephrectomies for a surgical disease is quite small compared to the large number of nephrectomies. It is imperative to identify in due time the secondary mechanism of hypertension in order to perform the surgical intervention which saves the kidney or prevents the extension to other organs. Although no special investigations were performed showing a possible preoperative RVH, it can be stated that the renal origin of the arterial hypertension can be established retrospectively, after nephrectomy. The monitoring of blood pressure values during several years is extremely important for establishing the etiology of renal hypertension.

Tanshinone II-A attenuates cardiac fibrosis and modulates collagen metabolism in rats with renovascular hypertension

The adaptive changes that develop in the pressure-overloaded left ventricular myocardium include cardiac hypertrophy and interstitial fibrosis. The objectives of the present study were to evaluate the effects of Tanshinone II-A, a bioactive diterpene quinone isolated from Danshen, on cardiac fibrosis and collagen metabolism in rats with renovascular hypertension. Male Sprague-Dawley rats were subjected to two-kidney two-clip (2K2C) or sham operation (sham) and treated with Valsartan (Val, 26.7 mg/kg/d), Tanshinone II-A (Tsn, 70, 35 mg/kg/d) or vehicle. Six weeks later, systolic blood pressure (BP), LV weight, collagen abundance, cardiac function parameters, hydroxyproline content and mRNA levels of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were evaluated. Both high-dose (Tsn-H, 70 mg/kg/d) and low-dose (Tsn-L, 35 mg/kg/d) of Tsn failed to attenuate 2K2C-induced BP elevation but significantly attenuated the attendant interstitial fibrosis. Val suppressed elevations of BP and left ventricular systolic pressure (LVSP) in 2K2C rats. Val and Tsn-H exerted comparable suppressive effects on the gene expression of MMP-9 and TIMP-1, while Val decreased the MMP-2 mRNA level without affecting the transcript levels of TIMP-2. Both Val and Tsn-H attenuated cardiac dysfunction, while Tsn-L showed slight improvement. These data demonstrate for the first time, that Tsn prevented cardiac fibrosis and improved cardiac function in a rat model of renovascular hypertensive independent of hypotensive effect. Tsn conferred its beneficial effects on the collagen metabolism probably through its regulation of transcript levels of the MMPs/TIMPs balance.

Successful percutaneous revascularization in a patient with a chronic totally occluded renal artery in an atrophied kidney

A 57-year-old man presented with renovascular hypertension with chronic kidney disease. 16-Multi-detector row computed tomography (MDCT) showed that the left renal artery was totally occluded and the left kidney was atrophied. The left atrophied kidney was hormonally active despite the desolation of glomerular filtration function. Percutaneous renal revascularization was successful for stenting this lesion. The renin activity in the left renal vein was decreased immediately after the procedure. He remained healthy with adequate blood pressure for three years. In this case, MDCT and renal vein renin measurement provided useful information for the decision to perform percutaneous renal revascularization.

Quantitative distribution and localization of calcitonin gene-related peptide-like cells in the stomach of two kidney, one clip rats

The majority of research for the calcitonin gene-related peptide (CGRP) in the stomach in the hypertension has been devoted to the submucosal blood flow, and no attention has been paid to its quantitative distribution in the gastric neuroendocrine cells. The aim of the present study was to examine the number and distribution of CGRP-containing cells in the pylorus of "two kidney, one clip" (2K1C) renovascular hypertension model in rats. The studies were carried out on the stomach of rats. After 6 week period of the renal artery clipping procedure, eight 2K1C rats developed stable hypertension. The hypertension significantly increased the number of endocrine cells pylorus immunoreactive to calcitonin gene-related peptide (CGRP) antisera. The differences between the hypertensive rats and the control group concerned not only the number of endocrine cells but also their distribution. CGRP participates in the regulation of cardiovascular functions both in normal state and in the pathophysiology of hypertension through interactions with the prohypertensive systems. The changes induced by hypertension in the neuroendocrine cells containing CGRP of the rats are discussed.

Antioxidant treatment reduces matrix metalloproteinase-2-induced vascular changes in renovascular hypertension

Mounting evidence indicates that structural and functional vascular changes associated with two-kidney, one-clip (2K-1C) hypertension result, at least in part, from altered activity of matrix metalloproteinases (MMPs). Because MMPs are upregulated by increased formation of reactive oxygen species (ROS), we hypothesized that antioxidant approaches could attenuate the increases in MMP-2 expression/activity and the vascular dysfunction and remodeling associated with 2K-1C hypertension. Sham-operated or 2K-1C hypertensive rats were treated with tempol 18 mg/kg/day or apocyanin 25 mg/kg/day (or vehicle). Systolic blood pressure was monitored weekly. After 8 weeks of treatment, aortic rings were isolated to assess endothelium-dependent and -independent relaxation. Quantitative morphometry of structural changes in the aortic wall was studied in hematoxylin/eosin sections. Aortic and systemic ROS levels were measured using dihydroethidine and thiobarbituric acid-reactive substances, respectively. Aortic MMP-2 levels and activity were determined by gelatin and in situ zymography, fluorimetry, and immunohistochemistry. Tempol and apocyanin attenuated 2K-1C hypertension (181+/-20.8 and 192+/-17.6 mm Hg, respectively, versus 213+/-18 mm Hg in hypertensive controls; both p<0.05) and prevented the reduction in endothelium-dependent vasorelaxation found in 2K-1C rats. Tempol, but not apocyanin (p>0.05), prevented the vascular remodeling found in 2K-1C rats (all p<0.01). Tempol was more effective than apocyanin in attenuating hypertension-induced increases in oxidative stress (both p<0.05), MMP-2 levels, and MMP-2 activity in hypertensive rats (all p<0.05). Our results suggest that antioxidant approaches decrease MMP-2 upregulation and attenuate the vascular dysfunction and remodeling during 2K-1C hypertension.

Mid-aortic syndrome with renovascular hypertension and multisystem involvement in a girl with familiar neurofibromatosis von Recklinghausen type 1

OBJECTIVES

Neurofibromatosis von Recklinghausen type 1 (NF1) is an autosomal dominant neurocutaneous disorder affecting one in 3 000-4 000 individuals. Mid-aortic syndrome (MAS) is a rare condition characterized by segmental narrowing of abdominal aorta and stenosis of its major branches - mainly renal arteries, including manifestation of renovascular hypertension. MAS can be caused by different diseases, including NF1.

MAIN FINDINGS

A 9 years old girl with primary diagnosis of NF1 combined with renovascular hypertension due to MAS, suffered of bilateral optic and chiasm glioma, pubertas praecox, speech disorder, light mental retardation and scoliosis. We have found a mutation in exone 34 of the NF1 gene (17q11.2). Her father has been also diagnosed with NF1 and hypertension developed at early age. He has the same mutation in exone 34 of NF1 gene. The girl is currently treated with conservative antihypertensive medication with positive effect. Bilateral optic and chiasm glioma are asymptomatic at the time and they had been without progress over period of time. Any vascular surgery, neurosurgical and oncological therapy are not indicated at the present time.

CONCLUSION

This article is a summary of clinical findings in patient with NF1 due to NF1 gene mutation in exone 34. It confirms the importance of complex multidisciplinar approach to examination and taking care of NF1 patients and their families.

Three-dimensional ultrasonography can detect the modulation of kidney volume in two-kidney, one-clip hypertensive rats

As volume changes are a typical finding in the two-kidney, one-clip hypertensive rat model (2K1C), it is of interest to investigate within what time frame these volume changes occur and their relation to hypertension. Kidney volume changes in Wistar rats were measured by three-dimensional (3D) ultrasonography (USG). Clipped induced stenosis was applied to the left renal artery in 11-wk-old animals (n = 8), using age-matched nonclipped rats as controls (n = 7). Ultrasonographic recordings were made before clipping and, thereafter, weekly with corresponding systolic blood pressure and body weight measurements. The nonclipped kidney showed increased volume at week 2, 5 and 7. Three wk after clipping, clipped kidneys were smaller than the nonclipped kidneys (0.47 +/- 0.11 mL versus 1.28 +/- 0.07 mL). No difference was found between the left and right kidney in the control group at any week. Blood pressure was significantly higher in the 2K1C hypertensive group 4 weeks after clipping (201 +/- 16 versus 139 +/- 4 mm Hg) with stable blood pressure thereafter. Three-dimensional USG showed that clipping caused a decrease in kidney volume from week 3 in the clipped kidney and a volume increase in the nonclipped kidney at week 2. A significant increase in blood pressure appeared after week 4.

Combined treatment with valsartan and spironolactone prevents cardiovascular remodeling in renovascular hypertensive rats

Treatment with an angiotensin blocker (ARB) and an aldosterone blocker has been shown to have beneficial effects on cardiac remodeling in several cardiac diseases. It is still not clear whether the combination of these drugs is more effective against cardiac remodeling than the use of either agent alone. We examined the effects of combined treatment with valsartan, an ARB, and spironolactone, an aldosterone blocker, on cardiac remodeling in the renovascular hypertensive (RHT) rat. The RHT rats were divided into 4 groups administered valsartan (3 mg/kg/day, ARB group), spironolactone (4 mg/kg/day, SPRL group), both drugs at these doses (combined group), or neither drug (untreated RHT group). After 5 weeks, systolic blood pressure was significantly reduced in the 3 treatment groups, however, there were no significant differences in the extent of blood pressure reduction among the 3 treatment groups. The heart weight/body weight ratio in each of the 3 treatment groups was significantly lower than that in the untreated RHT group. The degree of cardiac and perivascular fibrosis in the SPRL group and the combined group were significantly lower than that in the untreated RHT group. Myocyte remodeling in the ARB group and in the combined group was significantly smaller than that in the untreated RHT group. These results suggest that SPRL treatment prevents cardiac and perivascular fibrosis and ARB treatment suppresses the cellular hypertrophy of myocytes, and that, therefore, combined treatment with both drugs prevents cardiac remodeling by acting against both myocyte hypertrophy and cardiac fibrosis in RHT rats.

Cardiac and aortic structural alterations due to surgically-induced menopause associated with renovascular hypertension in rats

Menopause and hypertension independently alter cardiovascular remodelling, but little is known about their effect on left ventricular and aortic wall remodelling. Eight-weeks-old Wistar rats were divided into four groups of six animals each: Sham group, OVX group (ovariectomized rats), 2K1C (two-kidneys, one-clip rats) and OVX + 2K1C group and kept until 19 weeks. Blood pressure (BP) increased 12% in OVX group, 35% in 2K1C and OVX + 2K1C groups compared with sham group. Vaginal cytology showed Sham and 2K1C rats cycling normally, whereas OVX and OVX + 2K1C rats were persistently in dioestrus or proestrus. At euthanasia, left ventricle (LV) and thoracic aorta were removed and analysed (immunohistochemistry and stereology). LV mass/tibia length ratio and cross-sectional area of cardiomyocytes increased in all groups except Sham. The intramyocardial vascularization reduced 30% in comparison with Sham group, with no difference among OVX, 2K1C and OVX + 2K1C groups. The cardiac interstitium increased more than 45% in both 2K1C and OVX + 2K1C groups compared with Sham, but there was no significant difference between Sham and OVX groups. Nuclei number of LV cardiomyocyte diminished in OVX group, followed by 2K1C group and OVX + 2K1C group, with no difference between the 2K1C and the OVX + 2K1C groups. There was positive immunostaining for angiotensin II AT1 receptor in smooth muscle cell layer of aortic tunica media in all groups. These results show that both ovariectomy and renovascular hypertension enhance BP as a single stimulus and therefore produce adverse cardiac remodelling. However, renovascular hypertension exerts a far greater influence than surgically-induced menopause in this parameter.

Role of eicosanoids of the contralateral kidney in maintenance of two-kidney, one-clip renovascular hypertension in rats

OBJECTIVE

To elucidate the role of the eicosanoids prostaglandin E(2) (PGE(2)), 6-keto-prostaglandin F(1a) (PGF(1a)) and thromboxane B(2) (TXB(2)) in the maintenance of two-kidney, one-clip renovascular hypertension in rats.

MATERIAL AND METHODS

The right renal artery was constricted by a silver clip in 63 male Sprague-Dawley rats to induce hypertension, while a sham operation was performed in 17 control rats. Six months after the induction of hypertension, nephrectomy of the clipped kidney was performed. Nephrectomy was followed by a period of high sodium intake. Blood pressure and eicosanoid excretion were measured before and after nephrectomy of the clipped kidney, as well as during high sodium intake.

RESULTS

During the chronic phase of Goldblatt hypertension, the amount of vasoconstrictive TXB(2) excreted by the contralateral kidney increased compared to that in the controls, whereas PGE(2) excretion was unaffected. Eicosanoid excretion before and after removal of the clipped kidney did not differ between post-Goldblatt hypertensive and post-Goldblatt normotensive animals. During the period of high sodium intake, PGE(2) excretion increased only in control rats, being unaltered in Goldblatt hypertensive rats.

CONCLUSIONS

In the chronic phase of two-kidney, one-clip renovascular hypertension, the contralateral kidney of post-Goldblatt hypertensive and post-Goldblatt normotensive rats excretes more vasoconstrictive thromboxane in comparison to controls, whereas excretion of vasodilatory prostaglandin is not elevated. However, increased TXB(2) excretion and the absence of an increase in PGE(2) excretion from the contralateral kidney do not appear to be important for the maintenance of high blood pressure in this model of renovascular hypertension.

Antihypertensive therapy upregulates renin and (pro)renin receptor in the clipped kidney of Goldblatt hypertensive rats

Recently, a (pro)renin receptor has been identified which mediates profibrotic effects independent of angiotensin II. Because antihypertensive therapy induces renal injury in the clipped kidney of two kidney-1-clip hypertensive rats, we examined the regulation of renin and the (pro)renin receptor in this model. Hypertensive Goldblatt rats were treated with increasing doses of the vasopeptidase inhibitor AVE 7688 after which the plasma renin and prorenin as well as the renal renin and (pro)renin receptor expression were measured. The vasopeptidase inhibitor dose-dependently lowered blood pressure, which was associated with a massive increase in plasma prorenin and renin as well as increased renal renin expression. The (pro)renin receptor was upregulated in the clipped kidney of the Goldblatt rat indicating a parallel upregulation of renin and its receptor in vivo. Immunohistochemistry showed a redistribution of renin upstream from the glomerulus in preglomerular vessels and renin staining in tubular cells. Expression of the (pro)renin receptor was increased in the vessels and tubules. This upregulation was associated with thickening of renin-positive vessels and tubulointerstitial damage. We propose that renin and the (pro)renin receptor may play a profibrotic role in the clipped kidney of Goldblatt rats treated for hypertension.

Protective role of a novel erythrocyte-derived depressing factor on blood vessels of renovascular hypertensive rats

1. We have isolated a novel human erythrocyte-derived depressing factor (EDDF) that has a significant antihypertensive effect in various rat models of hypertension. The aim of the present study was to examine the mechanisms of action of EDDF on vascular function in two-kidney, one-clip (2K1C) renovascular hypertensive rats. 2. The EDDF was prepared from human erythrocytes. Experiments were performed in 18 male Wistar rats. The vascular ring perfusion assay and a two-photon laser scanning fluorescence microscope (TMP) were used to evaluate the vascular contractile response. The effects of EDDF on phenylephrine (PE)- and noradrenaline (NA)-induced vascular contraction were evaluated in 2K1C hypertensive rats. The proliferation and DNA synthesis in vascular smooth muscle cells (VSMC) were determined using the [3H]-TdR (thymidine) incorporation and 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Flow cytometry, reverse transcription-polymerase chain reaction and western blots were used to measure cell cycle and apoptotic profiles, platelet-derived growth factor (PDGF)-A expression and the activity of extracellular signal-regulated kinase (ERK)-1/2, as well as the expression of cyclin D1 and cyclin-dependent kinase (CDK) 4. 3. At 10(-5) g/mL, EDDF significantly decreased the PE- and NA-induced hypertensive vascular contraction. In addition, EDDF inhibited DNA synthesis in primary VSMC from 2K1C rats. The mRNA expression of PDGF-A in VSMC was twofold higher in 2K1C rats compared with control rats, whereas EDDF significantly inhibited the increment in PDGF-A mRNA expression. In addition, EDDF inhibited the phosphorylation of ERK1/2 and decreased the expression of cyclin D1 and CDK4; p21 (Cip1) levels were increased after treatment with EDDF. 4. In conclusion, EDDF inhibits VSMC proliferation in 2K1C rats through G0/G1 cell cycle arrest. The effects may be mediated, in part, by enhanced expression of p21 (Cip1) and the inhibition of ERK1/2 phosphorylation and the expression of cyclin D1/CDK4 and PDGF-A.

A pitfall of glomerular sieving: profibrotic and matrix proteins derive from the Bowman's capsule and not the glomerular tuft in rats with renovascular hypertension

BACKGROUND

The glomeruli in the non-clipped kidney of rats with 2-kidney, 1-clip hypertension are a classical model for studying the mechanisms of glomerular injury.

METHODS

In the present study, we compared the glomerular expression of PAI-1 and collagen I alpha1 mRNA from glomeruli isolated by the classic technique of sieving with the recently developed technique of tissue laser microdissection. For quantification of mRNA from both methods, real-time PCR was used.

RESULTS

Real-time PCR revealed a 9.0 +/- 1.3- and a 7.1 +/- 0.2-fold induction of PAI-1 and collagen I alpha 1, respectively, in the glomeruli from hypertensive rats isolated by sieving. However, in situ hybridization and microdissection revealed that expression of both mRNAs was mainly from the Bowman's capsule and not from the glomerular tuft (10.7 +/- 1.3- and 7.2 +/- 0.6-fold higher induction in whole glomeruli compared with tuft alone).

CONCLUSION

This emphasizes that studies focusing on processes in the mesangium, endothelial cells or podocytes should not rely on glomeruli obtained by sieving. Rather, a technique like the laser microdissection or in situ hybridization should be applied which allows the clear separation of different glomerular and periglomerular compartments.

Renovascular hypertension commencing during fetal life

We report three infants with severe, early hypertension due to unilateral renovascular disease, whose cardiovascular changes, or polycythaemia, or both, indicated they had been affected as fetuses. All underwent unilateral nephrectomy, and had a similar histology, with patchy areas having relatively normal glomeruli but immature proximal tubules. This pattern may be a marker for renovascular disease in fetal life.

Induction of heme oxygenase-1 in renovascular hypertension is associated with inhibition of apoptosis

The goal of this study was to characterize the impact of induction or inhibition of the heme-HO system on renal apoptosis in clipped and non-clipped kidneys from 2K1C hypertensive rats. Male Sprague-Dawley rats had a 0.25 mm silver clip placed around the left renal artery. Four groups of rats were studied: sham operated animals, 2K1C control rats, 2K1C rats received weekly injections of CoPP (5 mg/100 g body wt, administered subcutaneously), and 2K1C rats pretreated with SnMP (5 mg/ 100g body wt, administered intraperitoneally three times a week). The animals were sacrificed three weeks after surgery. We measured systolic blood pressure, plasma renin activity, non-clipped and clipped kidney HO-1 and HO-2 protein expression, HO activity, heme content, nitrotyrosine levels, and activation of selected pro- and anti-apoptotic proteins. Systolic blood pressure and plasma renin activity were significantly higher in 2K1C rats compared to sham rats. Compared to kidneys from sham animals, clipped kidneys from 2K1C rats showed a significant increase in HO-1 expression with increases in HO activity (26%), heme content (47%) and nitrotyrosine levels (49%), accompanied by an increase in caspase-3 and caspase-9 activity. In contrast, non-clipped kidneys from 2K1C rats showed no differences in HO-1 expression, HO activity, heme content, nitrotyrosine levels and caspase activity compared to sham rats. In clipped kidneys from 2K1C rats, inhibition of HO activity by SnMP augmented caspase-3 and caspase-9 activity and decreased expression of the anti-apoptotic Bcl-2 protein, while induction of HO-1 with CoPP strongly inhibited the activity of both caspases and increased the induction of Bcl-2 and Bcl-xl proteins. These findings demonstrate that the clipped kidneys responded to decreased renal perfusion pressure and increased oxidative stress by activation of the heme-HO system, which exerts antiapoptotic action via mechanisms involving decreased caspase-3 and caspase-9 activity, and increased expression of antiapoptotic molecules.

Renal Sympathetic Neuroeffector Function in Renovascular and Angiotensin II–Dependent Hypertension in Rabbits

We tested the hypotheses that the gains of specific renal sympathetic neuroeffector mechanisms are altered in secondary hypertension and that the nature of these alterations depends on the precise experimental setting of the kidney. Rabbits were sham operated, or made comparably hypertensive (mean arterial pressure increased 17% to 24%) by clipping the left or right renal artery or by chronic infusion of angiotensin II (20 to 50 ng kg −1 min −1 SC). Four to 6 weeks later, under pentobarbital anesthesia, the left renal nerves were sectioned and electrically stimulated at low (0 to 2 Hz) and high (4 to 8 Hz) frequencies. Neurally evoked reductions in total renal blood flow, cortical perfusion, urine flow, and sodium excretion and increases in renal norepinephrine spillover were not significantly greater in kidneys of hypertensive rabbits than normotensive controls. Neurally evoked increases in renal renin release and the slope of the relationship between renin release and norepinephrine spillover were less in kidneys of hypertensive rabbits than normotensive controls. Low-frequency renal nerve stimulation reduced medullary perfusion, which was negatively correlated with renal norepinephrine spillover in kidneys from all 3 groups of hypertensive rabbits but not normotensive controls. Two-hertz stimulation reduced medullary perfusion by 19% in hypertensive rabbits but not in normotensive rabbits. Thus, of all of the renal sympathetic neuroeffector mechanisms studied, only neural control of medullary perfusion was enhanced in these models of secondary hypertension. This effect appears to be mediated postjunctionally, not through enhanced neural norepinephrine release, and may contribute to the development and/or maintenance of hypertension in these models.

A clinical MRI investigation of the relationship between kidney volume measurements and renal function in patients with renovascular disease

Recent improvements in MR image acquisition and post-processing techniques have allowed quantitative kidney volume measurements to be derived from patient studies. These morphological indices can provide "snapshot" assessments that may be related to kidney function. The study objective was to measure cortical and total kidney volumes in patients with renovascular disease (RVD) using contrast-enhanced MR angiography (CE-MRA) in order to assess the reproducibility of the technique and to investigate associations between volumes and renal function as measured by glomerular filtration rate (GFR) calculations. 50 patients with RVD were scanned using CE-MRA. Kidney lengths, volumes and renal artery stenoses (RAS) were evaluated, and GFR was calculated using clinical formulae and nuclear medicine isotope renography. Mean MRI kidney lengths were 10.3+/-0.2 cm, and mean MRI volumes were 74.9+/-3.6 cm3 (cortical) and 128.5+/-5.3 cm3 (total). Kidneys supplied by moderately stenosed arteries had enlarged lengths and volumes, whilst those supplied by severely stenosed arteries had significantly smaller lengths (p<0.001) and volumes (p<0.001). There was a clear association between MRI cortical volume and GFR (r = 0.74, p<0.001, n = 48), but less so between kidney length and GFR (r = 0.54, p<0.001, n = 48). For individual patients, left/right cortical volume differences were small provided that severe RAS was not present, but large left/right volume differences and a GFR reduction were noted when severe RAS was present. The cortical volume distribution provides a useful single-timepoint indication of kidney function as defined by GFR, with no additional data acquisition required other than that of standard CE-MRA examination.