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Query: UMLS:C0403608 (ureter)
 9,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Partial obstruction of 1 ureter was created in newborn rats and its effects were studied in the adult rat. The obstructed renal pelvis was found to be about 6 times enlarged and the weight of the kidney was 85 per cent of the contralateral intact one. Despite considerable distortion of the inner medulla on the obstructed side, no loss of weight in this region was observed. The only changes observed with respect to tissue concentrations--which were significantly due to the obstruction--were increases in urea in the cortex (110 per cent) and in potassium in the inner medulla (21 per cent); thus, the changes were few and, in part, moderate. The findings are compared with previous observations of solute excretions and the pathophysiological implications are discussed. The conclusion is that although the inner medulla was considerably distorted, the solute content was far from being affected to a corresponding degree--at least not in this experimental preparation.
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PMID:Experimental obstructive hydronephrosis in newborn rats. V. Long-term effects on renal tissue solute content. 403 63

Hepatocytes isolated from livers of rats with various models of acute uremia (binephrectomy, ureter ligation, uranyl nitrate-induced, or ischemic ARF) were incubated with glucagon, adrenalin, or cyclic AMP using serine as a substrate. A marked increase in glucose production was observed in the hepatocytes of uranyl nitrate-treated, binephrectomized, and ureter-ligated rats compared to starved controls or sham-operated animals. This effect was strengthened in the presence of glucagon, adrenaline, or cyclic AMP. In liver cells of binephrectomized and ureter-ligated animals, the production of acetoacetate and beta-hydroxybutyrate was significantly higher than in controls and sham-operated rats. Oxoglutarate and ATP production was only enhanced after ureter ligation. The correlation between glucose concentration and the cytosolic redox state was different in control and sham-operated rats than in either uremic group. This study confirms earlier investigations of a key role of serine in carbohydrate metabolism in acutely uremic rats.
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PMID:Effect of serine on gluconeogenic ability of hepatocytes in acute uremia. 633 Apr 26

Micropuncture of the rat renal papilla has disclosed an outward transepithelial gradient for NaCl at the bend of Henle's thin loop and an electrical potential difference, lumen positive, in the ascending thin limb. Substantial water extraction and urea secretion occur somewhere proximal to the bend, but direct evidence for transepithelial NaCl movement across the rat descending thin limb is lacking. In the hamster, water is extracted and urea secreted, but no NaCl gradient has been found, and in Psammomys there is indirect evidence for transepithelial entry of NaCl into the descending limb. Fluid is diluted in the ascending thin limb by reabsorption of NaCl. The lack of unequivocal evidence for active NaCl reabsorption has stimulated a search for alternative mechanisms of osmotic work in the inner medulla. The collecting duct plays a crucial role by its differential reabsorption of water (primarily in the cortex) and urea (exclusively in the inner medulla) but has not yet been shown to supply useful energy to the concentrating mechanism by active sodium reabsorption. Exposure of the papillary tip by ureteral excision impairs urinary osmolality. Ureteral peristalsis normally causes intermittent flow of fluid in the collecting duct, but abolition of intermittent flow by paralysis of the ureter does not decrease urinary osmolality. Superperfusion of the exposed papilla by a urea solution prevents the decline in osmolality but the amount of urea used greatly exceeds that available from the urine. Nevertheless, it is the intactness of the ureter that is somehow essential to maximum urinary concentration, perhaps by preventing loss of solute from the papilla rather than by supplying energy.
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PMID:The renal concentrating mechanism: micropuncture studies of the renal medulla. 634 Oct 87

This study tested the ability of the converting enzyme inhibitor, captopril, to lessen the severity of acute renal failure following temporary occlusion of the renal artery. In the control group, 11 dogs were anesthetized with halothane, and the left kidney was isolated through a midline incision. The renal artery, vein, and ureter were then clamped for 120 min. Immediately after occlusion, the kidney was flushed with 40 ml of saline at 34 degrees C. When the clamp was released, a contralateral nephrectomy was performed and the animal allowed to recover. Serum creatinine and blood urea nitrogen levels were followed on a daily basis thereafter. Thirteen captopril-treated dogs were treated in the same fashion except that captopril (1.25 ml/kg, i.v.) was given prior to the 120-min period of renal ischemia. Three of 11 (27%) control dogs survived, whereas 10 of 13 (77%) captopril-treated animals survived (P less than 0.05). Serum creatinine (5.4 +/- 2.5 mg/dl) and serum urea nitrogen (96 +/- 33 mg/dl) peaked on day 8 in the captopril-treated group and were consistently lower than in the untreated group. These observations suggest that captopril is useful when temporary interruption of the renal circulation is encountered, such as in renal autotransplantation, cadaveric renal transplantation, and renal revascularization. These data also suggest that inhibition of the renin-angiotensin system may lessen the severity of acute renal failure following renal ischemia.
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PMID:Enhancement of recovery in postischemic acute renal failure with captopril. 637 20

Severance of the ureter beyond the renal papilla causes a fall in urinary osmolality, which suggests that exchange of water or solute between urine and renal parenchyma normally occurs in the intact renal pelvis. We examined water and solute flux in the renal pelvis with micropuncture and microcatheterization techniques. Four groups of antidiuretic rats were studied. Group I (n = 17) underwent micropuncture through the intact contracting ureter. Urine samples were obtained at the papillary tip, and in the pelvis beside the base of the extrarenal papilla. Urinary osmolality at the base, 880 +/- 97 mosmol/kg H2O (mean +/- SE), was less than that at the tip, 1,425 +/- 104 mosmol/kg H2O (P less than 0.005). In group II (n = 24), samples were analyzed for inulin and osmolality. In 15 rats (group IIA), comparison was made between base and tip samples. In the other nine animals (group IIB), comparisons were made among base, tip, and bladder samples and urea was also measured. In group II (A and B combined) urine-to-plasma (U/P) osmolality was lower at the base, 4.31 +/- 0.27, than at the tip, 6.08 +/- 0.23 (P less than 0.001), and U/P inulin was lower at the base, 192 +/- 25, than at the tip, 306 +/- 16 (P less than 0.001). In group IIB, the bladder urine had a lower U/P osmolality, 5.27 +/- 0.25, than the tip, 6.01 +/- 0.31 (P less than 0.02). The U/P urea was 59 +/- 10.6 (base), 98 +/- 9.4 (tip) (base vs. tip, P less than 0.05), and 81 +/- 6.5 (bladder, P less than 0.005, compared with tip). In group III (n = 8), samples were obtained by microcatheter from the fornices, the deepest intrarenal extensions of the pelvis, and compared with samples at the tip. Urinary osmolality was lower in the fornix, 646 +/- 106 mosmol/kg H2O, than at the tip, 1,296 +/- 99 mosmol/kg H2O (P less than 0.001). Similarly, U/P inulin was lower in the fornix, 48 +/- 14, than at the tip, 128 +/- 12 (P less than 0.001). The lower U/P inulin in the pelvic urine is the result of either the addition of fluid to the pelvis, or the backleak of inulin across the epithelium lining the pelvis. To verify that the pelvic epithelium was impermeable to inulin, in group IVA (n = 4) the left renal pelvis was superfused with a solution of chemical inulin. Cumulative absorption of inulin from the left kidney was 0.15 +/- 0.08% of that superfused. Using [14C]inulin in group IVB (n= 3), similar results were obtained (0.05 +/- 0.02%). These findings indicate that in the renal pelvis, fluid is added to urine after it emerges from the collecting ducts. We suggest that reflux of hyperosmotic urine over the renal papilla creates a transepithelial gradient for the flux of water into the pelvis. A model that incorporates diffusive and convective forces for water and solute transport is proposed to account for these findings.
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PMID:Examination of transepithelial exchange of water and solute in the rat renal pelvis. 650 75

Renal tubular function has been studied in pig fetuses of 105-112 d gestational age in new-born pigs 5-9 d old. The experiments were performed on anaesthetized animals, urines being collected by inserting a catheter into one ureter of the animal under study. The glomerular filtration rate was estimated and plasma concentrations and urinary excretion of the following substances were measured: sodium, potassium, calcium, ammonia, urea, phosphate, glucose fructose, creatinine, protein and exogenous 4-aminohippuric acid, and inulin. The reabsorption of water was considered in relation to the plasma vasopressin values. New-born pigs were loaded with glucose and fructose in order to determine the maximal tubular transport rate of these substances. Significant changes at birth occur in only a few functions of the tubulus system. Following delivery, major changes are: (1) the increased reabsorption of sodium and water which is probably the most important adaptation to extra-uterine life; (2) an apparent increasing impermeability of the tubular epithelium for creatinine, and (3) the direction of transport of fructose, which is reabsorbed by fetuses whereas neonates demonstrate a net secretion. Glucose and fructose are transported by different mechanisms. The experiments with fructose-loaded piglets demonstrate that there are at least two transport mechanisms for fructose: reabsorption - either passive or active - and secretion. The factors causing a shifting from one mechanism to the other are not yet known.
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PMID:Perinatal development of tubular function in the pig. 651 94

In acute rat kidney insufficiency, caused by bilateral nephrectomy or ureter ligation, functional activity of hepatocyte cytoplasmic structure was decreased. Estimation of the cytoplasmic structures functional state included studies of hexenal anesthesia duration, determination of cytochromes P-450 and b5 content in liver microsomal fraction as well as of activities of amidopyrine-N-demethylase and aniline hydroxylase. The alterations of these parameters occurred apparently due to the effect of high concentrations of urea on liver tissue.
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PMID:[Functional state of cytoplasmic reticulum of hepatocytes in rats with acute kidney insufficiency]. 662 92

Massive hematuria of renal origin was diagnosed in 4 dogs. In all dogs, blood and blood clots were clearly visible in the urine. Serum urea nitrogen and urine concentrating ability were normal. All dogs were anemic, and results of coagulation and platelet function tests were within normal limits. Excretory urography indicated hydroureter and hydronephrosis in all dogs, with filling defects in the bladder attributable to large blood clots in 2 dogs. Cystotomy and catheterization of the ureters enabled identification of one kidney as the source of bleeding in 3 dogs. Unilateral nephrectomy and ureterectomy resolved their hematuria. The results of histologic examination were normal in 2 dogs. The 3rd dog had evidence of pyelitis. Cystoscopy of the 4th dog did not reveal hematuria from either ureter. The dog was not operated on and it continued to have intermittent hematuria.
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PMID:Massive hematuria of nontraumatic renal origin in dogs. 662 96

Unilateral uareteral obstruction (UUO) in 6-week old male spontaneously hypertensive rats (6-w-SHR) accelerated the elevation of blood pressure and developed stroke with high frequency from 3 weeks after operation, whereas UUO had no effect in either 20-week old SHR or 6-week old normotensive Wistar Kyoto rats. Urinary protein excretion and plasma urea and renin concentrations in 6-w-SHR began to increase 2 weeks after UUO. Removal of the obstructed kidney in 6-w-SHR one week after UUO prevented the acceleration of hypertension, while the same treatment 2 weeks after operation did not. In the ureter-obstructed kidneys of 6-w-SHR, hydronephrotic atrophy was markedly observed already one week after operation, while in the opposite kidneys, hypertensive vascular lesions were manifested from the second week. These results indicate that with regard to reversibility of the hypertensive process, the obstructed kidney is more important in the early postoperative stages and the contralateral kidney more important later.
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PMID:Acceleration of hypotension and development of stroke in the spontaneously hypertensive rat by unilateral ureteral obstruction. 699 78

In 2 separate series of dogs a segment of ureter was isolated from both bladder and kidney and left in situ with an intact blood supply. Tense cysts formed in these sequestered segments regardless of whether the ends were occluded or the segments were split longitudinally and left open. The formation of these cysts can be prevented by the removal of the urothelium. The cyst contents were found consistently to have a sodium concentration below that of the simultaneously obtained serum concentration and urea concentration higher than the simultaneously obtained serum urea. Osmolalities and protein levels within the cysts were virtually identical to the serum levels.
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PMID:Sequestration of ureteric segments in dogs. 723 40


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