Renal microvascular actions of angiotensin II fragments.
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In the present study, we investigated renal microvascular responses to ANG-(1-7) and ANG IV. Diameter changes of small interlobular arteries, afferent arterioles, and efferent arterioles were assessed by using isolated perfused hydronephrotic rat kidneys. ANG-(1-7) and ANG IV concentration dependently decreased the diameters of all investigated renal microvessel, however, with a much lower potency than ANG II. The ANG II type 1 receptor blocker irbesartan completely reversed the responses to ANG-(1-7) and ANG IV, whereas the ANG II type 2 receptor blocker PD-123319 had no effect. Both ANG-(1-7) and ANG IV failed to alter renal microvascular constriction induced by ANG II. In addition, subnanomolar concentrations of ANG-(1-7) had no effect on the myogenic-induced tone of interlobular arteries and afferent arterioles. Thus our data indicate that at high concentrations, ANG-(1-7) and ANG IV are able to activate the ANG II type 1 receptor, thereby inducing renal microvascular constriction. The failure of ANG-(1-7) and ANG IV to reduce ANG II- and pressure-induced constrictions suggests that these fragments do not exert a vasodilator and/or ANG II antagonistic action in the kidney. (+info)
Changes in the upper urinary tract as demonstrated on intravenous pyelography and micturating cysto-urethrography in patients with spinal cord injury.
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1. Thirty-two per cent of cases examined by I.V.P. showed evidence of disease (20 per cent hydronephrosis, 12 per cent chronic pyelonephritis). 2. The incidence of V.U. reflux on micturating cysto-urethrography was 13 per cent. V.U. reflux is associated with chronic pyelonephritis in a high proportion of cases as would be expected. A normal pyelogram does not exclude V.U. reflux as mentioned by Cobb (1966). 3. Patients with complete paralysis show a significantly high incidence of chronic pyelonephritis, hydronephritis and V.U. reflux. 4. In case of unilateral hydronephrosis and chronic pyelonephritis there is a striking predilection for involvement of the right kidney. The cause for this is not evident but possibly the fact that the right ureter is shorter than the left is a factor. (+info)
Cytoprotective effects of nitrates in a cellular model of hydronephrosis.
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BACKGROUND: The earliest insult to the kidney following the onset of ureteral obstruction is a marked elevation in collecting system pressure. This imparts a mechanical stress that is transmitted directly from the collecting system to the kidney substance. Renal tubular injury is the principal functional and histological change encountered, with glomerular changes being less marked and occurring later. Nitric oxide (NO) has been shown to protect against renal injury in UO, but its mode of action has not been clearly defined. METHODS: MDCK (canine) and HK-2 (human) renal tubular cells were grown under control conditions or subjected to mechanical strain for periods of 24 and 48 hours. Cells were studied treated with or without Fas-antibody, etoposide or diethyl maleate (DEM) alone or in combination with NG-monomethyl l-arginine (L-NMMA), sodium nitroprusside (SNP) or l-arginine. Cell proliferation and apoptosis was determined using propidium iodide DNA staining. NO production and inducible NO synthase (iNOS) expression were measured by the Griess reaction and Western blotting, respectively. RESULTS: Cells subjected to mechanical strain displayed a decrease in the proportion of cells undergoing cell division. They also showed an increased susceptibility to apoptosis. Associated with this was a decrease in Bcl-2 expression. An increase in iNOS expression was seen in cells subjected to mechanical strain, but no increase in NO production. The cellular effects of mechanical strain were reversed by SNP and l-arginine. CONCLUSIONS: Culture of renal tubule cells in an environment of mechanical strain results in an imbalance in homeostasis and a net cell loss. This can be reversed by the administration of an NO donor or precursor. (+info)
Renal myogenic response: kinetic attributes and physiological role.
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The kinetic attributes of the afferent arteriole myogenic response were investigated using the in vitro perfused hydronephrotic rat kidney. Equations describing the time course for pressure-dependent vasoconstriction and vasodilation, and steady-state changes in diameter were combined to develop a mathematical model of autoregulation. Transfer functions were constructed by passing sinusoidal pressure waves through the model. These findings were compared with results derived using data from instrumented conscious rats. In each case, a reduction in gain and increase in phase were observed at frequencies of 0.2 to 0.3 Hz. We then examined the impact of oscillating pressure signals. The model predicted that pressure signals oscillating at frequencies above the myogenic operating range would elicit a sustained vasoconstriction the magnitude of which was dependent on peak pressure. These predictions were directly confirmed in the hydronephrotic kidney. Pressure oscillations presented at frequencies of 1 to 6 Hz elicited sustained afferent vasoconstrictions and the magnitude of the response depended exclusively on the peak pressure. Elevated systolic pressure elicited vasoconstriction even if mean pressure was reduced. These findings challenge the view that the renal myogenic response exists to maintain glomerular capillary pressure constant, but rather imply a primary role in protecting against elevated systolic pressures. Thus, the kinetic features of the afferent arteriole allow this vessel to adjust tone in response to changes in systolic pressures presented at the pulse rate. We suggest that the primary function of this mechanism is to protect the glomerulus from the blood pressure power that is normally present at the pulse frequency. (+info)
Pulmonary hyalinizing granuloma with hydronephrosis.
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A 49-year-old man was admitted for the evaluation of a bilateral mass shadow in his chest X-ray film. No definitive diagnosis was established either by brushing cytology or biopsy through bronchoscopy. No malignancies were suggested by general work-up. Both masses were surgically removed, and were diagnosed as pulmonary hyalinizing granuloma (PHG). Fifteen months later, low grade fever continued and the renal function decreased. Laboratory examinations revealed bilateral hydronephrosis with polyclonal hypergammaglobulinemia. The findings of abdominal CT and urography were compatible with retroperitoneal fibrosis. Steroid treatment completely reversed the initial abnormality in laboratory data and the symptoms disappeared. (+info)
Application of transarterial embolization of renal artery in rabbits with experimental hydronephrosis.
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This study was performed to validate the procedure of transarterial embolization of the renal artery (TAE-RA) using iohexol-ethanol solution in rabbits with unilateral experimental hydronephrosis and to evaluate the embolized kidney and contralateral normal kidney using B-mode ultrasonography and color Doppler ultrasonography. Experimental hydronephrosis was induced at 17 days after ligation of unilateral ureter in 13 rabbits. Renal artery embolization was performed using selective catheterization in the hydronephrotic kidney of eight rabbits and electrocardiography, oxygen saturation, body temperature, pulse, and respiratory rate were within normal ranges during procedures. Iohexol-ethanol solution was used as embolic material. Average ethanol dose for renal artery embolization was 1.4 +/- 0.7 ml/kg. There were no rabbits expired after TAE-RA and no side effects associated with regurgitation of iohexol-ethanol solution. In color Doppler ultrasonographic findings, there was no blood flow into the embolized kidneys treated by TAE-RA, however, blood flow signal was found in hydronephrotic kidney not treated by TAE-RA. Ultrasonographically, the mean longitudinal length of the embolized kidney significantly decreased at 2 and 3 months after TAE-RA. No significant difference of resistive index values was found between contralateral normal kidney of rabbits treated by TAE-RA and contralateral normal kidneys of rabbits treated with nephrectomy. We may conclude that TAE-RA with iohexol-ethanol solution is a viable alternative to nephrectomy in rabbits with unilateral hydronephrosis. (+info)
Renal dysplasia in nephrectomy specimens from adolescents and adults.
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In a review of 156 total or partial nephrectomy specimens from patients over the age of 12 years, renal dysplasia was found 14 times. The cases were divided initially into five groups on the basis of the predominant pathological changes, namely (1) dysplasia (14 cases), (2) chronic pyelonephritis (31 cases), (3) calculous inflammation (58 cases), (4) hydronephrosis (35 cases), and (5) miscellaneous (18 cases). The diagnosis of dysplasia was made on gross and microscopic criteria and included 12 of segmental dysplasia, one of total dysplasia, and one multicystic dysplastic kidney. The principal differential diagnosis is from the irregularly scarred chronic pyelonephritic kidney. The criteria for the separation of the two are emphasized and, in particular, the distinction from those pyelonephritic kidneys with aglomerular scars. A high incidence of anomalies of drainage was found in association with dysplasia, but such were not always present. It was not thought that intrarenal reflux in infancy was an aetiological factor. Six of the cases presented with urinary infection, but only two had hypertension. It was thought that acquired glomerular damage was more important in the aetiology of hypertension than segmental glomerular agenesis. (+info)
A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1 null mutant mice develop renal lesions mimicking obstructive nephropathy.
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BACKGROUND: A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1 is distinguished from other a disintegrin and metalloproteinase molecules by the presence of thrombospondin type 1 motifs at its C-terminus and anchors to the extracellular matrix. We studied the biological role of ADAMTS-1 in the kidney. METHODS: We developed ADAMTS-1 null mice by replacing exons 2-4, which encode most of the metalloproteinase domain, with the neomycin resistance gene. RESULTS: In normal mice, ADAMTS-1 was detected in the epithelial cells of collecting ducts, and more intensely in the urinary epithelium at the ureteropelvic junction in kidney. We found that targeted disruption of the mouse ADAMTS-1 gene resulted in enlarged renal calices accompanied by bilateral hydronephrosis and papillary atrophy approximately 4 weeks after birth. Electron microscopic examination revealed the fibrotic changes and hypervascularity of capillaries between the urinary epithelial cell layer and smooth muscle cell layer at the ureteropelvic junction. CONCLUSION: ADAMTS-1 appears necessary for normal kidney morphology and function. Moreover, the resemblance of the renal phenotype to human ureteropelvic junction obstruction may provide a clue to the pathogenesis of this common congenital disease. (+info)