Defective trophoblast invasion underlies fetal growth restriction and preeclampsia-like symptoms in the stroke-prone spontaneously hypertensive rat.

STUDY QUESTION: What is the impact of chronic hypertension on placental development, fetal growth and maternal outcome in the stroke-prone spontaneously hypertensive rat (SHRSP)? SUMMARY ANSWER: SHRSP showed an impaired remodeling of the spiral arteries and abnormal pattern of trophoblast invasion during placentation, which were associated with subsequent maternal glomerular injury and increased baseline hypertension as well as placental insufficiency and asymmetric fetal growth restriction (FGR). WHAT IS KNOWN ALREADY: A hallmark in the pathogenesis of preeclampsia (PE) is abnormal placentation with defective remodeling of the spiral arteries preceding the onset of the maternal syndrome. Pregnancies affected by chronic hypertension display an increased risk for PE, often associated with poor maternal and fetal outcomes. However, the impact of chronic hypertension on the placentation process as well as the nature of the factors promoting the development of PE in pregnant hypertensive women remain elusive. STUDY DESIGN, SIZE, DURATION: Timed pregnancies [n = 5] were established by mating 10-12-week-old SHRSP and Wistar Kyoto (WKY, normotensive controls) females with congenic males. Maternal systolic blood pressures (SBPs) were recorded pre-mating, throughout pregnancy (GD1-19) and post-partum by the tail-cuff method. On selected dates, 24 h urine- and blood samples were collected, and animals were euthanized for isolation of implantation sites and kidneys for morphometrical analyses. PARTICIPANTS/MATERIALS, SETTING, METHODS: The 24 h proteinuria and the albumin:creatinine ratio were used for evaluation of maternal renal function. Renal injury was assessed on periodic acid Schiff, Masson's trichrome and Sirius red stainings. Placental and fetal weights were recorded on gestation day (GD)18 and GD20, followed by determination of fetal cephalization indexes and developmental stage, according to the Witschi scale. Morphometric analyses of placental development were conducted on hematoxylin-eosin stained tissue sections collected on GD14 and GD18, and complemented with immunohistochemical evaluation of isolectin B4 binding for assessment of placental vascularization. Analyses of vascular wall alpha actin content, perforin-positive natural killer (NK) cells and cytokeratin expression by immunohistochemistry were used for evaluation of spiral artery remodeling and trophoblast invasion. MAIN RESULTS AND THE ROLE OF CHANCE: SHRSP females presented significantly increased SBP records from GD13 to GD17 (SBPGD13 = 183.9 ± 3.9 mmHg, P < 0.005 versus baseline) and increased proteinuria at GD18 (P < 0.01 versus WKY). Histological examination of GD18 kidneys revealed glomerular enlargement and mesangial matrix expansion, which were not evident in pregnant WKY or age-matched virgin SHRSP. At GD20, SHRSP displayed a significant reduction of placental mass (P < 0.01 versus WKY) and signs of placental insufficiency (i.e. hypertrophy and reduced branching morphogenesis of the labyrinth layer), associated with decreased offspring weights and increased cephalization index (both P < 0.001 versus WKY) indicating asymmetric FGR. Notably, SHRSP placentas displayed an incomplete remodeling of spiral arteries starting as early as GD14, with luminal narrowing and reduced densities of perivascular NK cells followed by decreased infiltration of endovascular trophoblasts at GD18. LARGE SCALE DATA: n/a. LIMITATIONS, REASONS FOR CAUTION: A pitfall of the present study is the differences in the blood pressure profiles between rats and humans (i.e. unlike pregnancies affected by PE, blood pressure in SHRSP and other hypertensive rat models decreases pre-delivery), which limits extrapolation of the results. WIDER IMPLICATIONS OF THE FINDINGS: Our findings provide new insights on the role of chronic hypertension as a risk factor for PE by interfering with early events during the placentation process. The SHRSP strain represents an attractive model for further studies aimed at addressing the relative contribution of intrinsic (i.e. placental) and extrinsic (i.e. decidual/vascular) factors to defective spiral artery remodeling in pregnancies affected by PE. STUDY FUNDING AND COMPETING INTEREST(S): This work was supported by research grants from Fundación Florencio Fiorini to G.B., from Charité Stiftung to S.M.B. and University of Buenos Aires (UBACyt) to J.T. The authors have no competing interests to declare.

Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload.

We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.

Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney.

Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na(+), K(+)-ATPase inhibition. Present results show that CNP did not affect either (3)H-dopamine uptake in renal tissue or Na(+), K(+)-ATPase activity; meanwhile, Ang-(1-7) was able to increase (3)H-dopamine uptake and decreased Na(+), K(+)-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na(+), K(+)-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on (3)H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on (3)H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on (3)H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na(+), K(+)-ATPase activity inhibition, contributing to its natriuretic and diuretic effects.

Long-term phosphodiesterase 5 inhibitor administration reduces inflammatory markers and heat-shock proteins in cavernous tissue of Zucker diabetic fatty rat (ZDF/fa/fa).

Oxidative stress and nitrosative stress present in type 2 diabetes mellitus (T2DM) and metabolic syndrome (MS) induce inflammatory response in diverse tissues including cavernous tissue (CT). Heat-shock proteins (HSPs) have an important role in modulating and repairing tissue injury, although their participation in CT in T2DM is unclear. Beyond the specific action of phosphodiesterase type 5 inhibitors (PDE5i) on erectile function, it has been proposed that chronic administration of these agents improves endothelial function and ameliorates fibrotic changes. The aim of this study was to determine in CT of Zucker Diabetic Fatty (ZDF) rat, an experimental model of T2DM and MS: (1) the degree of oxidative stress and nitrosative stress; (2) the magnitude of inflammatory markers such as tumor necrosis factor-α (TNFα) and interleukin 6 (IL6); (3) immunoexpression of HSP70 and HSP27; (4) how a long-term PDE5i administration may modify these variables. For 6 months, (1) untreated ZDF; (2) ZDF+Sildenafil (Sil) and (3) control Lean Zucker Rat (LZR) received no treatment, were studied. Penises were processed for functional 'in vitro' studies, oxidative and nitrosative stress evaluation and immunohistochemistry in CT using TNFα; IL6; nitrotyrosine, HSP70 and HSP27 antibodies. ZDF+Sil presented better relaxation in corporal strips versus untreated ZDF. Furthermore, ZDF+Sil presented less lipoperoxidation in CT versus untreated ZDF. The activity of antioxidant enzymes CuZn superoxide dismutase (CuZnSOD) and glutathione peroxidase (GPx) was also reduced in untreated ZDF in CT along with a decrease in glutathione versus untreated ZDF. Nitrotyrosine expression was increased in untreated-ZDF rats versus ZDF+Sil and LZR. TNFα and IL6 were decreased in CT in ZDF+Sil versus untreated ZDF. Additionally, the expression of HSP70 and HSP27 was reduced in CT in ZDF+Sil versus untreated ZDF. In conclusion, this study provides substantial evidence supporting a protective role of a long-term therapy with Sil on CT in a recognized animal model of T2DM and MS.

Role of angiotensin II and oxidative stress in renal inflammation by hypernatremia: benefits of atrial natriuretic peptide, losartan, and tempol.

The body regulates plasma sodium levels within a small physiologic range, despite large variations in daily sodium and water intake. It is known that sodium transport in the kidneys plays an important role in hypoxia, being the major determinant of renal oxygen consumption. Tubular epithelial cell hypoxia is an important contributor to the development of renal inflammation, and the damage may progress to structural injury, ending in acute renal failure. In this review, we will summarize the renal inflammatory effects of high acute plasma sodium (acute hypernatremia), and the molecular mechanisms involved. We will also discuss recent findings related to the role of oxidative stress and angiotensin II (Ang II) in the pathogenesis of renal injury. We will comment on the effects of agents used to prevent or attenuate the inflammatory response, such as the atrial natriuretic peptide, the superoxide dismutase mimetic - tempol, and losartan.

Nitrosative Stress and Apoptosis by Intravenous Ferumoxytol, Iron Isomaltoside 1000, Iron Dextran, Iron Sucrose, and Ferric Carboxymaltose in a Nonclinical Model.

Iron is involved in the formation as well as in the scavenging of reactive oxygen and nitrogen species. Thus, iron can induce as well as inhibit both oxidative and nitrosative stress. It also has a key role in reactive oxygen and nitrogen species-mediated apoptosis. We assessed the differences in tyrosine nitration and caspase 3 expression in the liver, heart, and kidneys of rats treated weekly with intravenous ferumoxytol, iron isomaltoside 1000, iron dextran, iron sucrose and ferric carboxymaltose (40 mg iron/kg body weight) for 5 weeks. Nitrotyrosine was quantified in tissue homogenates by Western blotting and the distribution of nitrotyrosine and caspase 3 was assessed in tissue sections by immunohistochemistry. Ferric carboxymaltose and iron sucrose administration did not result in detectable levels of nitrotyrosine or significant levels of caspase 3 vs. control in any of the tissue studied. Nitrotyrosine and caspase 3 levels were significantly (p<0.01) increased in all assessed organs of animals treated with iron dextran and iron isomaltoside 1000, as well as in the liver and kidneys of ferumoxytol-treated animals compared to isotonic saline solution (control). Nitrotyrosine and caspase 3 levels were shown to correlate positively with the amount of Prussian blue-detectable iron(III) deposits in iron dextran- and iron isomaltoside 1000-treated rats but not in ferumoxytol-treated rats, suggesting that iron dextran, iron isomaltoside 1000 and ferumoxytol induce nitrosative (and oxidative) stress as well as apoptosis via different mechanism(s).

Effects of iron deficiency anemia and its treatment with iron polymaltose complex in pregnant rats, their fetuses and placentas: oxidative stress markers and pregnancy outcome.

OBJECTIVE: Iron deficiency anemia (IDA) can severely impair the outcome of pregnancy. IDA has been shown to cause oxidative stress, which may be exacerbated by oral iron therapy. In this study, the effects of IDA and its treatment with iron polymaltose complex/folic acid (IPC/FA) were examined in anemic pregnant rats, their fetuses and placentas. STUDY DESIGN: Hematological variables and oxidative stress markers in the liver, heart and kidney were evaluated in non-anemic, anemic and IPC/FA-treated pregnant rats and their fetuses. Markers for oxidative stress, inflammation and hypoxia were assessed in the placentas of all groups. RESULTS: IDA was shown to increase oxidative stress levels in all the studied organs and in placenta as well as hypoxia and inflammation in placenta. IPC/FA treatment corrected IDA measured by the hemoglobin level, serum iron level and transferrin saturation. The oxidative stress levels in all the studied organs and in placentas of the IPC/FA-treated group were comparable to those of the non-anemic group. The number of fetuses and the neonatal and placental weight were lower in the anemic group compared to the non-anemic and IPC/FA-treated groups. CONCLUSIONS: The current study shows that IDA in pregnant rats impaired pregnancy outcome, increased the expression of hypoxia and inflammatory markers in the placenta, and increased oxidative stress in dams, fetuses and placentas. Treatment with oral IPC/FA corrected the IDA as well as reduced the levels of oxidative stress and inflammatory markers close to non-anemic control values in all the studied organs.

Urinary excretion of low molecular weight proteins in patients with pure monoclonal light chain proteinuria.

BACKGROUND: Because urinary low molecular weight protein (LMWP) measurement shows changes in renal integrity at an early stage, beta2-microglobulin (B2m), retinol-binding protein (RBP) and alpha1-microglobulin (A1m) were evaluated in 24-hour urine collection of 65 patients with pure monoclonal light chain (MLC) proteinuria and in 47 patients with different kidney diseases (DKDs) for comparison. METHODS AND RESULTS: Albumin, kappa, lambda, A1m and B2m were measured by immunonephelometry. RBP was determined by ELISA. The mean values of LMWP quantitation were significant for origin of the disease (MLC and DKD) (p<0.05) and renal failure (RF) (p<0.001) (MANOVA). Tukey HSD test only showed significant differences for LMWP between MLC patients with RF and DKD patients without RF. The mean value of A1m was different between patients with and without RF in each group (p<0.05 for MLC, and p<0.01 for DKD). In the group without RF, the frequency of A1m excretion above 12 mg/L differed between MLC patients and DKD patients (p<0.01). CONCLUSION: A tubular dysfunction occurred in a great number of patients excreting pure MLC even in those with well-preserved renal function, as it did in patients with DKDs. In patients with MLC without RF, A1m might be measured for the early recognition of tubular involvement.

Acute sodium overload produces renal tubulointerstitial inflammation in normal rats.

The aim of the present study was to determine whether acute sodium overload could trigger an inflammatory reaction in the tubulointerstitial (TI) compartment in normal rats. Four groups of Sprague-Dawley rats received increasing NaCl concentrations by intravenous infusion. Control (C): Na+ 0.15 M; G1: Na+ 0.5 M; G2: Na+ 1.0 M; and G3: Na+ 1.5 M. Creatinine clearance, mean arterial pressure (MAP), renal blood flow (RBF), and sodium fractional excretion were determined. Transforming growth factor beta1 (TGF-beta1), alpha-smooth muscle actin (alpha-SMA), RANTES, transcription factor nuclear factor-kappa B (NF-kappaB), and angiotensin II (ANG II) were evaluated in kidneys by immunohistochemistry. Animals with NaCl overload showed normal glomerular function without MAP and RBF modifications and exhibited a concentration-dependent natriuretic response. Plasmatic sodium increased in G2 (P < 0.01) and G3 (P < 0.001). Light microscopy did not show renal morphological damage. Immunohistochemistry revealed an increased number of ANG II-positive tubular cells in G2 and G3, and positive immunostaining for NF-kappaB only in G3 (P < 0.01). Increased staining of alpha-SMA in the interstitium (P < 0.01), TGF-beta1 in tubular cells (P < 0.01), and a significant percentage (P < 0.01) of positive immunostaining for RANTES in tubular epithelium and in glomerular and peritubular endothelium were detected in G3 > G2 > C group. These results suggest that an acute sodium overload is able 'per se' to initiate TI endothelial inflammatory reaction (glomerular and peritubular) and incipient fibrosis in normal rats, independently of hemodynamic modifications. Furthermore, these findings are consistent with the possibility that activation of NF-kappaB and local ANG II may be involved in the pathway of this inflammatory process.

Angiotensin II blockade improves mitochondrial function in spontaneously hypertensive rats.

Angiotensin II can induce oxidant stress by stimulating vascular superoxide production. Hypertension promotes mitochondrial function decline in brain, liver and heart. The aim of this study was to investigate whether a) hypertension is associated to kidney mitochondrial dysfunction, and b) angiotensin II blockade can reverse potential mitochondrial changes in hypertension. Four-month-old male spontaneously hypertensive rats (SHR) received drinking water containing candesartan (7.5 mg/kg/day, SHR+Cand), or no additions (SHR) for 4-months. Eight-month-old Wistar-Kyoto rats (WKY), that received water with no additions, were used as control. Systolic blood pressure, proteinuria, cortical glomerular area, and glomerular and tubulointerstitial alpha-smooth muscle actin labeling, were significantly higher, and creatinine clearance was significantly lower, in SHR relative to WKY and SHR+Cand. In SHR, kidney mitochondria membrane potential, and nitric oxide synthase and cytochrome oxidase activities were significantly lower than in WKY and SHR+Cand. In SHR, mitochondrial hydrogen peroxide production was significantly higher than in WKY and SHR+Cand. The results suggest that, in hypertension, increased mitochondrial oxidant production may mediate kidney mitochondria dysfunction. Candesartan preserved mitochondrial function, probably favoring the maintenance of adequate cellular and tissue function in the kidney. The known renal protective effects of candesartan in hypertension may be related to the improvement of mitochondrial function. This may be an additional or alternative explanation for some of the beneficial effects of AT1 receptor antagonists.

Reduced cardiac expression of plasminogen activator inhibitor 1 and transforming growth factor beta1 in obese Zucker rats by perindopril.

OBJECTIVE: To determine whether angiotensin converting enzyme inhibition by perindopril can reduce cardiac transforming growth factor beta1 (TGFbeta1) and plasminogen activator inhibitor 1 (PAI-1) and therefore control collagen accumulation in an animal model with the metabolic syndrome such as the obese Zucker rat (OZR). ANIMALS: Male OZR (group 1, n = 10); OZR treated with perindopril (group 2, n = 10); and lean Zucker rats (group 3, n = 10). METHODS: During six months, group 2 received 3 mg/kg/day of perindopril orally and group 1 and group 3 were given a vehicle. Hearts were processed for pathology studies including immunohistochemical analysis with antibodies to PAI-1, TGFbeta1, collagen type I, and collagen type III. RESULTS: Group 2 had lower blood pressure (126.7 (2) v 148.6 (2.7) mm Hg, p < 0.01) than untreated OZR and had decreased cardiac PAI-1 (3.6 (0.4) v 13.5 (1.7)% of positive area/field, p < 0.01), TGFbeta1 in myocytes (0.13 (0.1) v 9.14 (4.7)%/area, p < 0.01) and in interstitium (19.8 (6.8) v 178.9 (27.4) positive cells/area, p < 0.01), collagen I (3 (0.8) v 13.3 (1)%/area, p < 0.01), collagen III (5 (0.6) v 9.5 (0.9)%/area, p < 0.01), and collagen I to collagen III ratio (0.59 (0.13) v 1.40 (0.15) p < 0.01) compared with untreated OZR. CONCLUSION: These results suggest that perindopril reduces cardiac PAI-1 and TGFbeta1 and ameliorates cardiac fibrosis in a rat model with multiple cardiovascular risk factors.

Candesartan cilexetil protects cavernous tissue in spontaneously hypertensive rats.

In previous experiments, our group demonstrated morphological changes in erectile tissue from male spontaneously hypertensive rats (SHR). The present study was performed to determine whether an angiotensin II receptor blocker could protect cavernous tissue (CT) from these structural alterations in SHR. Male SHR and Wistar-Kyoto (WKY) rats were studied during 4 months. Rats were divided into three groups: SHR (n=10), SHR with candesartan cilexetil (n=10) and WKY rats (n=10). Candesartan cilexetil 7.5 mg/kg/day was administered orally throughout the study. CT was processed for pathology studies. The amount of (1) cavernous smooth muscle (CSM), (2) vascular smooth muscle (VSM), (3) collagen type III, and the rat endothelial cell antibody (RECA-1)/tunica media ratio in cavernous arteries were evaluated. SHR with candesartan cilexetil showed a lower blood pressure, a lower percentage of CSM, smaller VSM area, with a higher RECA-1/media ratio, and a lower percentage of collagen type III, when compared to untreated SHR. In addition, SHR showed a positive correlation between systolic blood pressure (SBP) and CSM amount (r=0.91; P<0.01), and SBP and the percentage of collagen type III (r=0.88; P<0.01); these correlations were not observed either in SHR treated with candesartan cilexetil or in WKY rats. We conclude that candesartan cilexetil provides a significant protective role against morphologic changes in vessels as well as in cavernous spaces of the erectile tissue, caused by high blood pressure, in SHR.

Morphological modifications in clitoris and vagina in spontaneously hypertensive rats.

We evaluated possible morphological alteration in clitoris and vagina from spontaneous hypertensive rats (SHR) and normotensive WKY rats. Clitoris and vagina were processed by Masson's trichrome, anti-alpha-smooth-muscle actin, anticollagen type I (COL I) and type III (COL III), and anti-TGFbeta(1). SHR presented higher amount of clitoral cavernous smooth muscle (CSM), vascular smooth muscle; TGFbeta(1) in clitoral vessel wall; higher wall/lumen ratio in both vaginal and clitoral vessels; and remarkable interstitial fibrosis, expressed by a higher amount in interstitial COL I and III in both clitoris and vagina, compared to WKY rats. Nerve fibers from clitoral and vaginal tissue in SHR showed important fibrosis at perineurium. SHR showed positive correlation between systolic blood pressure (SBP) and clitoral CSM; SBP and fibrosis in clitoris; and SBP and COL I and III in clitoris, respectively. Similar findings were observed between SBP and COL I and III in vagina. In conclusion, SHR present morphologic changes in clitoral vessels as well as in clitoral cavernous space, which have a high positive correlation with the high blood pressure level. Moreover, the increase in extracellular matrix affects not only the clitoral and vaginal interstitium but also the nerve structures from both clitoris and vagina.

Protective role of enalapril for chronic tubulointerstitial lesions of hyperoxaluria.

PURPOSE: Hyperoxaluria is a recognized cause of tubulointerstitial lesions and it may contribute to chronic renal failure. In previous studies we demonstrated that enalapril was effective against the progression of tubulointerstitial lesions in a 4-week hyperoxaluria rat model. We evaluated whether the action of enalapril on the tubulointerstitial lesions produced by hyperoxaluria persisted for a long period. MATERIALS AND METHODS: Two-month-old male Sprague-Dawley rats were divided into 4 groups of 12 each, including 1--control animals given tap water, 2--animals with hyperoxaluria, 3--animals with hyperoxaluria plus enalapril, 4--animals with enalapril. Hyperoxaluria in groups 2 and 3 rats was induced by administering 1% ethylene glycol, a precursor for oxalates, in the tap water continuously throughout the whole study. Meanwhile, groups 3 and 4 received 20 mg./l. enalapril in the drinking water. At the end of the study renal tubulointerstitial lesions were evaluated by immunostaining using monoclonal antibodies against macrophage infiltrates (ED1), tubulointerstitial alpha-smooth muscle actin and transforming growth factor-beta1. The lesions were quantified by semiquantitative scores. Creatinine clearance and urinary albumin excretion were also determined. RESULTS: There was no difference in urine oxalate excretion in groups 2 and 3. Group 3 rats treated with enalapril showed fewer tubulointerstitial lesions than nontreated group 2 rats, as indicated by the mean scores plus or minus standard error of mean for inflammatory infiltrate (2.16 +/- 0.2 versus 0.83 +/- 0.16), tubular atrophy (2 +/- 0.27 versus 0.66 +/- 0.14), interstitial fibrosis (2.5 +/- 0.15 versus 0.5 +/- 0.1), glomerular ED1 (1.75 +/- 0.25 versus 0.16 +/- 0.11), interstitial ED1 (2.33 +/- 0.18 versus 0.58 +/- 0.10) tubular transforming growth factor-beta1 (2.09 +/- 0.08 versus 0.91 +/- 0.14), interstitial transforming growth factor-beta 1 (2.33 +/- 0.22 versus 0.66 +/- 0.12), tubulointerstitial alpha-smooth muscle actin (2.91 +/- 0.22 versus 0.83 +/- 0.16), lower urinary albumin excretion (35.5 +/- 2.7 mg. daily versus 10.9 +/- 1) and higher creatinine clearance (2.29 +/- 0.04 ml. per minute versus 2.54 +/- 0.03, all p <0.05). CONCLUSIONS: Based on our results we believe that enalapril would provide a beneficial effect against chronic tubulointerstitial lesions caused by oxalates.

Potassium citrate administration ameliorates tubulointerstitial lesions in rats with uric acid nephropathy.

Although controversial, chronic uric acid nephropathy is a tubulointerstitial disease capable of developing renal function loss. On the other hand, potassium citrate (KCi) administration has demonstrated to be effective in calcium as well as uric acid nephrolithiasis therapy. Therefore, the aim of the present study was to evaluate the possible benefit of KCi treatment in the prevention or amelioration of renal interstitial damage in uric acid nephropathy. Two-month-old male Sprague-Dawley rats were divided into 3 groups: G1 hyperuricemic (HU), G2 hyperuricemic + KCi (HU+KCi), and G3 KCi. G1 and G2 were fed on oxonic acid (inhibitor of rat liver uricase), and a uric acid supplement, during 4 weeks. G2 and G3 were given 2% KCi in drinking water, and G1 regular tap water and standard rat chow. At the end of the study, renal tissue was processed for light and electron microscopy and immunostaining by alpha-smooth muscle actin (SMA). Tubulointerstitial lesions and the amount of alpha-SMA immunostaining in renal tissue were evaluated by histomorphometric quantitation. Rats belonging to the hyperuricemic groups treated with KCi (G2) showed fewer tubulointerstitial lesions as follows: % tubular atrophy: 1.7 +/- 0.3 versus 7.2 +/- 1.2, p < 0.05; inflammatory cells infiltrate (number of cells/area): 0.6 +/- 0.1 versus 2.4 +/- 0.2, p < 0.01; % interstitial fibrosis (cortex): 3.3 +/- 0.3 versus 9.3 +/- 0.5, p < 0.05; % interstitial fibrosis (medulla): 5.2 +/- 0.3 versus 21.9 +/- 1.2, p < 0.01, lower albuminuria (32.8 +/- 11.2 mg/day versus 128.5 +/- 10.4, p < 0.01), higher creatinine clearance ( 1.36 +/- 0.02 ml/min versus 0.74 +/- 0.01, p < 0.01 ) and less percentage of alpha-SMA in renal tissue (1.8 +/- 0.1 versus 10.5 +/- 1.4, p < 0.05), when compared with the hyperuricemic group not treated with KCi (G1). These data suggest that KCi administration could provide a substantial benefit in the regard to tubulointerstitial lesion and progressive renal damage.

Morphological changes in cavernous tissue in spontaneously hypertensive rats.

Erectile dysfunction has an increased prevalence in hypertensive patients and is associated with cardiovascular diseases. For many years the discussion has been polarized on whether in hypertensive patients, it is the arterial hypertension or the antihypertensive therapy that is the cause of male erectile dysfunction. The aim of our study was to determine the morphologic changes in cavernous tissue (CT) in an animal model of arterial hypertension. Male spontaneously hypertensive rats (SHR) (n = 15) and normotensive Wistar-Kyoto (WKY) rats (n = 15) were studied for 8 months. Animals were allowed to drink tap water and fed a standard rat chow ad libitum. Systolic blood pressure (SBP) was measured monthly by the tail/cuff method. At the end of the experiment all the animals were sacrificed for microscopic studies. Cavernous tissue was processed by hematoxylin and eosin, Masson's trichrome, and monoclonal anti-alpha smooth muscle actin. Cavernous smooth muscle (CSM) and vascular smooth muscle (VSM) proliferation and CT fibrosis were evaluated by a semiquantitative score. SHR showed a higher proliferative score in CSM (2.7 +/- 0.28 v 1.1 +/- 0.07; P < .001), as well as in VSM (2.7 +/- 0.25 v 1 +/- 0.05; P < .001), and higher CT fibrosis score (2.8 +/- 0.28 v 0.1 +/- 0.07; P < .001), when compared to WKY rats. Furthermore, SHR showed a positive correlation between SBP and CSM proliferative score (r2 = 0.9277), SBP and VSM proliferative score (r2 = 0.8828), and SBP and CT fibrosis score (r2 = 0.7775). In addition, an increase in the surrounding connective tissue at the perineurium and endoneurium of the amielinic nerves in CT was observed in the SHR group. According to these results we conclude that SHR present morphologic changes in vessels as well as in cavernous spaces of the erectile tissue that have a high positive correlation with high blood pressure. Moreover, the increase in extracellular matrix expansion seems to affect not only the interstitium but also the neural structures of the penis.

Effects of amlodipine on tubulointerstitial lesions in normotensive hyperoxaluric rats.

Although controversial, a number of reports have suggested that calcium antagonists can retard or prevent the progression of various renal diseases in experimental models. Nevertheless, there are few data related to tubulointerstitial changes in these studies. On the other hand, hyperoxaluria is a recognized cause of tubulointerstitial lesions, and this could contribute to the development of hypertension and chronic renal failure. The aim of the present study was to evaluate a possible beneficial effect of amlodipine, a 1,4-dihydropyridine class of calcium antagonist, in a model of primary tubulointerstitial lesion produced by hyperoxaluria. Two-month-old male Sprague-Dawley rats were separated into 4 groups for a 4-week period: G1 (control; tap water only); G2 (hyperoxaluric); G3 (hyperoxaluric plus amlodipine treatment); and G4 (amlodipine treatment). G2 and G3 rats were given 1% ethylene glycol (a precursor for oxalates) in drinking water, and G3 and G4 rats were given amlodipine 2 mg. kg(-1). d(-1) by gavage. At the end of the study, we evaluated by semiquantitative scores (0 to 4) the different renal tubulointerstitial lesions, urinary albumin excretion, renal function by creatinine clearance, and blood pressure. Rats belonging to the hyperoxaluric group treated with amlodipine (G3) had fewer tubulointerstitial lesions, as follows: (1) inflammatory infiltrate score: 3.31+/-0.07 versus 0.23+/-0.12; P<0.05; (2) tubular atrophy score: 3.33+/-0.33 versus 0.50+/-0.22, P<0.05; (3) interstitial fibrosis score: 2.76+/-0.34 versus 0.31+/-0. 16, P<0.05; (4) oxalate deposits score: 3.66+/-0.33 versus 0.09+/-0. 08, P<0.05; (5) lower urinary albumin excretion (11.3+/-2 versus 27+/-4.5 mg/d, P<0.01); and (6) higher creatinine clearance (1. 22+/-0.08 versus 1.13+/-0.08, P<0.01) compared with the hyperoxaluric group untreated with amlodipine (G2). On the other hand, there were no significant changes in blood pressure in any group. In view of these data, we suggest that amlodipine, probably by nonhemodynamic mechanisms of action, can provide an important benefit in the prevention of epithelial tubular cell injury and inflammatory response and therefore in the prevention of the progressive tubulointerstitial fibrosis caused by oxalates.

Factores de progresión del daño renal crónico en nefrectomía subtotal / Progression features of chronic renal damage following a partial nephrectomy

El objetivo de este trabajo fue evaluar las diferentes alteraciones renales morfológicas y funcionales secundarias a la pérdida de la masa renal por nefrectomía subtotal (Nx5/6) e investigar los mecanismos patogénicos involucrados en el daño TI en este modelo.Se utilizaron machos Sprague-Dawley (280-290 g) divididos en dos grupos. GI, (Nx5/6) N=15 y G2, (Sham) n= 15, los que fueron sometidos a una operación simulada "sham operation". La duración del experimento fue 24 semanas obteniéndose en el período basal y cada 4 semanas hasta la finalización del estudio, registros de presión arterial (PA) y muestras de sangre y orina. Los resultados indicaron que este modelo de nefrectomía subtotal, produce en 24 semanas un DRC con ascenso de la PA correlacionándose significativamente con el ascenso de la creatininemia

Factores de progresión del daño renal crónico en nefrectomía subtotal / Progression features of chronic renal damage following a partial nephrectomy

El objetivo de este trabajo fue evaluar las diferentes alteraciones renales morfológicas y funcionales secundarias a la pérdida de la masa renal por nefrectomía subtotal (Nx5/6) e investigar los mecanismos patogénicos involucrados en el daño TI en este modelo.Se utilizaron machos Sprague-Dawley (280-290 g) divididos en dos grupos. GI, (Nx5/6) N=15 y G2, (Sham) n= 15, los que fueron sometidos a una operación simulada "sham operation". La duración del experimento fue 24 semanas obteniéndose en el período basal y cada 4 semanas hasta la finalización del estudio, registros de presión arterial (PA) y muestras de sangre y orina. Los resultados indicaron que este modelo de nefrectomía subtotal, produce en 24 semanas un DRC con ascenso de la PA correlacionándose significativamente con el ascenso de la creatininemia

Enalapril prevents tubulointerstitial lesions by hyperoxaluria.

Hyperoxaluria is a recognized cause of tubulointerstitial lesions, and this could contribute to development of hypertension and chronic renal failure. Enalapril has been effective against the progression of tubulointerstitial lesions in various animal models. The aim of the present study was to evaluate the usefulness of enalapril on the tubulointerstitial damage produced by oxalates. Two-month-old male Sprague-Dawley rats were separated into 4 groups, control with tap water (G1), hyperoxaluric (G2), hyperoxaluric+enalapril (G3), enalapril (G4), for 4 weeks. G2 and G3 rats were given 1% ethyleneglycol (ETG, precursor for oxalates), and G3 and G4 rats were given enalapril 20 mg/L in drinking water. At the end of the study, we evaluated renal tubulointerstitial lesions by a semiquantitative score. Urine albumin excretion, serum and urine nitric oxide production, tubulointerstitial immunostaining by alpha-smooth muscle actin, transforming growth factor-beta1, and collagen type III were measured. Rats belonging to the hyperoxaluric group treated with enalapril (G3) showed fewer tubulointerstitial lesions (1.3+/-0.2 versus 3+/-0.2; P<0.01), lower urine albumin excretion (8+/-2 mg/d versus 25+/-2 mg/d; P<0.01), less percentage of alpha-smooth muscle actin in renal interstitium (2+/-0.4% versus 13.5+/-2.4%; P<0.01), less percentage of transforming growth factor-beta1 in tubulointerstitial area (3.3+/-1% versus 13.3+/-2. 1%; P<0.01), less percentage of collagen type III interstitial deposition (0.7+/-0.5% versus 7+/-2.6%; P<0.01), and increased NO production in serum as well as urine (both P<0.01), when compared with the hyperoxaluric group not treated with enalapril (G2). Considering these data, we believe that enalapril, by several mechanisms of action, could provide an important benefit in the prevention of inflammatory response, transforming growth factor-beta1 tubulointerstitial production, collagen type III interstitial deposition, and finally, the progressive tubulointerstitial fibrosis caused by oxalates.