UMLS:C0033687 - FACTA Search

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Query: UMLS:C0033687 (proteinuria)
24,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, we have reported that endothelin-1 (ET-1) production is increased in blood vessels and glomeruli of rats with chronic renal failure. This study was design to investigate the role of angiotensin II (Ang II) in endogenous ET-1 production in rats with reduced renal mass. One week after subtotal (5/6) nephrectomy, uremic rats were divided into three groups, and received either no treatment, the Ang II subtype 1 receptor (AT1) antagonist losartan (10 mg/kg/day), or the angiotensin-converting enzyme inhibitor (ACE-I) captopril (30 mg/kg/day) for 6 weeks. Sham-operated rats were used as controls and received no treatment. The levels of immunoreactive ET-1 (ir-ET-1) in plasma and urine, as well as in vascular and renal tissues, were determined by radioimmunoassay (RIA) after extraction. In uremic rats, losartan and captopril completely prevented the increase in systolic blood pressure. At week 6, plasma ir-ET-1 was similar in the different groups of uremic rats and in the controls. However, ir-ET-1 concentration in the mesenteric arterial bed, the thoracic aorta, preglomerular arteries, and glomeruli, as well as urinary ir-ET-1 excretion were significantly greater in uremic-untreated rats compared to controls (P < .01). Treatment of uremic rats with losartan or captopril reduced irET-1 concentration in the thoracic aorta and preglomerular arteries (P < .05), but ir-ET-1 concentration in the mesenteric arterial bed was unchanged. Although both drugs completely prevented the increase in proteinuria, losartan but not captopril significantly reduced ir-ET-1 concentration in glomeruli (P < .05) and normalized urinary ir-ET-1 excretion. This indicates that increased ET-1 production in blood vessels and glomeruli of uremic rats is modulated, at least in part, by Ang II through the AT1 receptor. The beneficial effects of the AT1 antagonist losartan could be attributable to the attenuation of Ang II-induced ET-1 production in this rat remnant kidney model of chronic renal failure, whereas those of the ACE-I captopril are not related to changes in ET-1 production in glomeruli.
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PMID:Effects of losartan and captopril on endothelin-1 production in blood vessels and glomeruli of rats with reduced renal mass. 971 93

Angiotensin II, the principal effector of the renin-angiotensin cascade, stimulates a variety of physiological responses that support blood pressure and renal function. Abnormal generation of angiotensin II also contributes to the pathogenesis of hypertension, arterial diseases, cardiac hypertrophy, heart failure and proteinuric progressive renal diseases. It is well recognized that angiotensin-converting enzyme inhibitors effectively limit the progression of diabetic and non-diabetic proteinuric renal diseases towards end-stage renal disease, a capacity not necessarily shared by other blood pressure lowering agents. Whether angiotensin II type 1 receptor antagonists have the same renoprotective effect as angiotensin-converting enzyme inhibitors in progressive renal diseases remains ill defined. Angiotensin II type 1 receptor antagonists as antiproteinuric agents have been used originally in animal models of renal disease progression. Results have shown that angiotensin II type 1 receptor blockers are as effective as angiotensin-converting enzyme inhibitors in normalizing proteinuria in models of renal disease. Studies in humans are very few, but those that have been undertaken report consistent antiproteinuric effects of angiotensin II type 1 receptor antagonists that are similar to those with angiotensin-converting enzyme inhibitors. Long-term studies, however, are required to examine whether the antiproteinuric effects of angiotensin II type 1 receptor antagonists can be translated into renoprotection.
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PMID:Angiotensin II receptor antagonists and treatment of hypertension and renal disease. 981 6

Persistent proteinuria is considered a deleterious prognostic factor in most progressive renal diseases. However, the mechanisms by which proteinuria induces renal damage remain undetermined. Since proximal tubular cells possess all the machinery to generate angiotensin II (Ang II), we approached the hypothesis that proteinuria could elicit the renal activation of the renin-angiotensin system in a model of intense proteinuria and interstitial nephritis induced by protein overload. After uninephrectomy (UNX), Wistar-Kyoto rats received daily injections of 1 g BSA or saline for 8 days. The mean peak of proteinuria was observed at the fourth day (538+/-89 versus 3+/-1 mg/24 h in UNX controls; n=12; P<0.05) and was increased during the whole study period (at the eighth day: 438+/-49 mg/24 h; n=12; P=NS). Morphological examination of the kidneys at the end of the study showed marked tubular lesions (atrophy, vacuolization, dilation, and casts), interstitial infiltration of mononuclear cells, and mesangial expansion. In relation to UNX control rats, renal cortex of BSA-overloaded rats showed an increment in the gene expression of angiotensinogen (2.4-fold) and angiotensin-converting enzyme (ACE) (2.1-fold), as well as a diminution in renin gene expression. No changes were observed in angiotensin type 1 (AT1) receptor mRNA expression in both groups of rats. By in situ reverse transcription-polymerase chain reaction and immunohistochemistry, ACE expression (gene and protein) was mainly localized in proximal and distal tubules and in the glomeruli. By immunohistochemistry, angiotensinogen was localized only in proximal tubules, and AT1 receptor was localized mainly in proximal and distal tubules. In the tubular brush border, an increase in ACE activity was also seen (5. 5+/-0.5 versus 3.1+/-0.7 U/mg protein x10(-4) in UNX control; n=7; P<0.05). Our results show that in the kidney of rats with intense proteinuria, ACE and angiotensinogen were upregulated, while gene expression of renin was inhibited and AT1 was unmodified. On the whole, these data suggest an increase in Ang II intrarenal generation. Since Ang II can elicit renal cell growth and matrix production through the activation of AT1 receptor, this peptide may be responsible for the tubulointerstitial lesions occurring in this model. These results suggest a novel mechanism by which proteinuria may participate in the progression of renal diseases.
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PMID:Angiotensin-converting enzyme is upregulated in the proximal tubules of rats with intense proteinuria. 1002 37

Angiotensin (Ang) II type 1 (AT1) receptor antagonists are orally active drugs that specifically block the subtype 1 of Ang receptors. In contrast to AT1 receptor antagonists, angiotensin-converting enzyme (ACE) inhibitors block the actions of Ang II incompletely. Furthermore, the bradykinin-potentiating effects of ACE inhibitors may contribute to the mechanism of action of ACE inhibitors. Data in experimental animals suggest that AT1 receptor antagonists decrease the glomerular filtration rate (GFR) to a lesser degree than ACE inhibitors. The greater effect of ACE inhibitors in decreasing glomerular pressure was attenuated with a bradykinin antagonist. In rat models of renal damage with proteinuria, acute reduction of proteinuria was seen with ACE inhibitors but not with AT1 receptor antagonists, whereas long-term reductions of proteinuria were of similar magnitude with both agents. Renal histology after several months revealed that AT1 receptor antagonists and ACE inhibitors were equally renoprotective in various renal damage models. AT1 receptor antagonists, like ACE inhibitors, exhibit a natriuretic effect equal to moderate doses of a thiazide diuretic. In patients with severe volume depletion, use of AT1 receptor antagonists may lead to acute renal failure. Valsartan was tested in a double-blind trial in patients with moderate to severe renal failure and led to a substantial decrease in diastolic and systolic blood pressure, whereas there was no difference from placebo for changes in GFR. Urine protein increased with placebo and decreased with valsartan. The data indicate that valsartan in renal failure patients is effective in lowering blood pressure while leaving renal excretory function unaltered. Whether there is a renoprotective effect can only be shown in long-term trials, which are under way.
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PMID:Valsartan and the kidney: present and future. 1002 53

There is now abundant evidence that treatment with angiotensin-converting enzyme inhibitors (ACE-I) ameliorates the progression of chronic renal disease. Attention has therefore focused on the role of the renin angiotensin-aldosterone (RAA) system in mediating the development of progressive glomerulosclerosis and angiotensin II (Ang II) has been implicated in several processes thought to be important in the pathogenesis of this entity. Conversely, ACE is also known to catalyse the breakdown of bradykinin. Thus, ACE-I treatment results in elevated bradykinin levels which may cause selective efferent arteriolar dilatation, suggesting an alternative explanation for the beneficial effects of this class of drugs in chronic renal disease. The development of specific angiotensin type 1 receptor antagonists (AT1RA) has provided a means of testing the relative importance of these two mechanisms. In addition, AT1RAs differ from ACE-I in their effect on the RAA system in other aspects which may represent therapeutic advantages. This paper reviews studies which have compared ACE-I and AT1RAs in several rat models of chronic renal disease. Most have found similar beneficial effects including amelioration of proteinuria and glomerulosclerosis, which suggests that the effects of ACE-I are due to a reduction in Ang II activity and not due to increased levels of bradykinin. One long-term study has suggested greater renal protection with candesartan than with enalapril. However, conclusions as regards the relative efficacy of these two groups of agents in ameliorating the progression of chronic renal disease await the results of further long-term studies.
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PMID:ACE-I vs angiotensin II receptor antagonists: prevention of renal injury in chronic rat models. 1007 21

We hypothesized that short-term exposure to angiotensin II (Ang II) could result in structural and functional changes in the kidney that would favor sodium retention and the development of sustained hypertension. To test this hypothesis, rats were exposed to pressor doses (435 ng. kg-1. min-1) of Ang II for 2 weeks. The infusion of Ang II was associated with acute hypertension, renal dysfunction, proteinuria, and focal tubulointerstitial and vascular damage. At sites of the tubulointerstitial damage, there was a reduction in peritubular capillary endothelial cell staining. By use of immunostaining, we found focal loss of endothelial nitric oxide synthase (eNOS) in the peritubular capillaries at sites of injury and a generalized reduction in eNOS in collecting ducts, thin loops of Henle, and vascular bundles in the medulla. When the Ang II infusion ended, the rats became normotensive and renal function returned toward normal. However, exposure of the rats to high salt diet (4% NaCl) resulted in the redevelopment of hypertension after 3 to 4 weeks. Rats maintained on a high salt diet with no prior exposure to Ang II and rats placed on low salt diet (0.1% NaCl) after exposure to Ang II remained normotensive. Thus, we report a new model of salt-sensitive hypertension induced by transient exposure to pressor doses of Ang II. The mechanism may relate to microvascular injury with peritubular capillary loss coupled with functional changes, such as a loss in intrarenal nitric oxide formation, that could alter the ability of the kidney to excrete a salt load.
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PMID:Salt-sensitive hypertension develops after short-term exposure to Angiotensin II. 1020 40

Angiotensin II antagonists block the actions of angiotensin II by occupying the AT1 receptors. With this blockade there is no bradykinin increase, the angiotensin II synthetized by the cardiac chymase is also blocked, and the AT2 receptor is stimulated (antiproliferative effect). In animal experiments, losartan reverses left ventricular hypertrophy, inhibits myocardial fibrosis and diabetic glomerulosclerosis and significantly protects from vascular cerebral diseases. In humans, the efficacy of the angiotensin II antagonists and that of other antihypertensives is similar and is potentiated by the addition of a thiazide. They are very well tolerated and no important adverse reactions are reported. Losartan decreases insulin resistance, has a very favourable hemodynamic and neurohormonal profile in patients with cardiac insuficiency, reverses proteinuria and has a uricosuric effect. Angiotensin II antagonists are a step forward towards the ideal antihypertensive drugs.
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PMID:[Therapy of arterial hypertension with angiotensin receptor blockers]. 1037 49

It has been well demonstrated that angiotensin-converting enzyme inhibitors (ACEIs) can retard the progression of renal failure and kidney sclerosis in patients and animal models with glomerular diseases. The aim of this study was to observe the influences of ACEI on intrarenal Ang II and TGFbeta1 local formation and their relation to renal protective effects. Experimental glomerulosclerosis with nephrotic syndrome was induced in unilateral nephrectomized rats with repeated injections of adriamycin. Rats were randomly divided into three groups: 1) a sham-operated control group (n=8); 2) an NS group treated with ACEI (benazepril 4 mg/kg/d) (n=10), and 3) an NS group not treated (n=10). After 8 wk, serum, urine and renal tissue were collected for study. ACE activity and Ang II concentration in renal tissue were measured by colorimetry and radioimmunoassay, respectively. Immunohistochemistry staining was employed for transforming growth factor-beta1 (TGFbeta1) and extracellular matrix (ECM) examination. TGFbeta1 mRNA was assessed by in situ hybridization. Compared with those of non-treated nephropathy rats, ACE activity (13.39+/-5.02 vs. 49.13+/-12.92 U/ml, p< 0.01) and Ang II (402.61+/-80.22 vs. 751.63+/-137.45 pg/mg/pr p < 0.01) in renal tissue were significantly inhibited in the rats treated with ACEI. At the same time, proteinuria was significantly reduced (155.06+/-103.56 vs. 421.11+/-148.45 mg/24 h, p < 0.01) and renal function improved (Scr 76.3+/-33.1 vs. 107.1+/-71.0, p < 0.05), concomitant with a reduction in the glomerular sclerosis index (30.6+/-19.5 vs. 120.3+/-61.9, p < 0.01) and a reduction in ECM accumulation such as Col IV, III, LN and FN (29.2+/-9.8 vs. 76.8+/-12.4; 29.5+/-12.4 vs. 85.9+/-11.5; 26.0+/-5.1 vs. 69.6+/-1.73; 32.4+/-12.4 vs. 70.5+/-13.5; p< 0.01 in all cases). In the ACEI treated group, these histologic benefits coincided with a reduced expression of TGFbeta1 in both tubular cells and sclerosed glomeruli in protein as well as mRNA level. These findings provide further evidence that ACEI (benazepril) can prevent the progression of renal damage in both the function and morphologic changes which associated with a down-regulation of intrarenal Ang II level through the relative inhibition of renal ACE activity. The blocking of the intrarenal renin angiotensin system (RAS) might contribute to the inhibition of TGFbeta1 local formation and the TGFbeta1-mediated ECM accumulation that are related to the renal protective effects of ACEI.
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PMID:Renal protective effects of blocking the intrarenal renin-angiotensin system. 1051 46

Mibefradil and amlodipine are calcium antagonists with different channel selectivities. Mibefradil blocks both L- and T-type calcium channels; although in the usual pharmacological doses, it predominantly blocks the T-type channels. In contrast, amlodipine selectively blocks L-type channels. The goal of the present study was to assess whether this differential selectivity would result in different effects on end-organ damage in experimental hypertension. For this purpose, deoxycorticosterone acetate (DOCA)-salt hypertensive rats were treated either with equipotent doses of mibefradil or amlodipine (30 mg. kg(-1). d(-1) as food admix). Despite the fact that both drugs decreased systolic arterial pressure to the same extent (140+/-5 mm Hg in the mibefradil group and 144+/-3 mm Hg in the amlodipine group versus 225+/-5 mm Hg in the untreated-DOCA group), only mibefradil decreased proteinuria (35. 5+/-6.5 versus 103.3+/-14.1 mg/24 h in untreated DOCA-salt animals) and prevented glomerular lesions. Both drugs, however, prevented the occurrence of vascular renal lesions. To elucidate the mechanism responsible for this difference, we evaluated in an additional series of experiments the effects of mibefradil and amlodipine on plasma and renal renin concentrations, as well as the effects of the addition of enalapril, an ACE inhibitor, given on top of both drugs on proteinuria. Amlodipine, in contrast to mibefradil, markedly stimulated the plasma (17.8+/-2.6 ng Ang I. mL(-1). h(-1) in the amlodipine group versus 3.9+/-0.4 ng Ang I. mL(-1). h(-1) in the mibefradil group and 3.2+/-0.3 ng Ang I. mL(-1). h(-1) in the untreated-DOCA group) and renal (2.42+/-0.37 ng Ang I. mL(-1). h(-1) in the amlodipine group versus 0.36+/-0.04 ng Ang I. mL(-1). h(-1) in the mibefradil group and 0.26+/-0.08 ng Ang I. mL(-1). h(-1) in the untreated-DOCA group) renin concentrations. Stimulation of the renin-angiotensin system could explain the absence of a renal protective effect of amlodipine. This was also suggested by the fact that enalapril given in addition to amlodipine could decrease proteinuria. In conclusion, T-type channel blockade by mibefradil decreases blood pressure without stimulation of the renin-angiotensin system and therefore prevents most of the glomerular damage in DOCA hypertensive rats.
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PMID:Contrasting effects of selective T- and L-type calcium channel blockade on glomerular damage in DOCA hypertensive rats. 1052 45

In this study, we investigated the regulation and physiological role of heme oxygenase-1 (HO-1) in the kidney of rats with hypertension. Rats were continuously administered either angiotensin II (Ang II) or norepinephrine with an osmotic minipump for up to 7 days. Ang II infusion decreased the glomerular filtration rate (GFR) as determined through creatinine clearance (3.2+/-0.2 versus 1.2+/-0.2 mL/min with Ang II infusion, P<0.01) and increased proteinuria (9. 7+/-1.3 versus 28.1+/-7.2 mg/d with Ang II infusion, P<0.01). In contrast, norepinephrine did not alter these laboratory values. Ang II infusion significantly increased HO-1 expression in mRNA (442+/-98% of control at day 5, P<0.01) and protein levels (314+/-49% of control at day 5, P<0.01). Immunohistochemistry showed that in the kidney of normotensive rats, HO-1 was expressed mainly in the basal side in the renal tubules. After Ang II infusion, HO-1 staining was more extensively dispersed in the tubular epithelial cells. The intraperitoneal administration of zinc protoporphyrin, an HO inhibitor, to Ang II-infused rats further decreased GFR (0.8+/-0. 1 mL/min) and increased proteinuria (52.5+/-13.0 mg/d). In contrast, the administration of hemin, an HO inducer, ameliorated the Ang II-induced decrease in GFR (2.4+/-0.2 mL/min) and increase in proteinuria (9.3+/-4.5 mg/d). These data suggest that HO-1 upregulation in the kidney of Ang II-induced hypertensive rats may exert a renoprotective effect against Ang II-induced renal injury.
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PMID:Heme oxygenase-1 is upregulated in the kidney of angiotensin II-induced hypertensive rats : possible role in renoprotection. 1072 May 98

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