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

Acute disruption of the renal blood supply has been shown by several workers to alter renal cortical metabolic functions and some transport processes. The present study was designed to examine acute ischemic effects on transport functions for both organic and inorganic substances. Acute clamping of the renal artery, renal vein, and ureter for 45 min produces a reversible disruption of tissue electrolyte and water balance. Longer occlusion appeared to produce irreversible effects. Alpha-Aminoisobutyrate (AIB) and lactate-stimulated rho-aminohippurate (PAH) transport were altered selectively by the 45-min occlusion. A longer occlusion period also depressed base-line PAH and tetraethylammonium (TEA) transport. Some of the depression of the organic compound transport functions are reversible. Renal cortical oxygen consumption measured in vitro was affected minimally.
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PMID:Effects of acute anoxia on renal transport processes. 99 35

Multiple vascular connections in normal avian kidneys make it difficult to experimentally manipulate renal blood flow patterns and perfusion pressures. In this study, hemostatic clips were used to obstruct the ureter of one kidney at the level of the ischiadic artery (IA) in anesthetized 3-wk-old chicks (Gallus domesticus). Kidney tissue upstream from the ureteral obstruction degenerated, leaving an intact caudal renal division with one route of arterial inflow branching from the IA. Renal function studies were conducted, using general anesthesia, when the birds reached 12-15 wk of age. A snare placed around the IA was used to unilaterally decrease renal arterial perfusion pressure (RAPP) for the experimental kidney. Under control conditions (snare loose), urine flow rates (UFR), glomerular filtration rates (GFR), clearance of p-aminohippuric acid, and fractional excretion of Na, K, Ca, and PO4 did not differ significantly, per gram of kidney weight, when experimental and intact contralateral kidneys were compared. Gradual tightening of the IA snare reduced RAPP stepwise. UFR decreased significantly from the initial control value when RAPP reached 40 mmHg, and urine flow ceased completely when RAPP reached 30-35 mmHg. In four of five birds, GFR did not decrease significantly between 110 and 60 mmHg but did decrease significantly below 60 mmHg. Urine osmolality was inversely correlated with UFR. Clearance of PAH did not decrease significantly from control values as RAPP ranged from 100 to 37 mmHg, possibly caused by increased renal portal blood flow. Overall, these results provide the first direct demonstration that in domestic fowl GFR is autoregulated at reduced RAPP.
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PMID:Model for evaluating avian renal hemodynamics and glomerular filtration rate autoregulation. 338 17

In 64 dogs the influence of a sudden unilateral ureteral obstruction on renal blood flow (RBF), on renal extraction of PAH and 131I-hippurate and on kidney function as determined by clearance methods was studied. By measuring the venous blood flow, using the method of Bretschneider, a decrease of the RBF was observed generally although in some cases the RBF remained constant or even increased. The arterial blood flow, controlled by electromagnetic means, showed a tendency to increase but in some cases remained constant or decreased. In all cases, independent of the reaction of the RBF to acute ureteral obstruction, a significant decrease of the renal extraction of PAH as well as of 131I-hippurate was observed. This decrease of kidney function was found by conventional methods (PAH- and 125I-hippurate clearance in "steady state" technique), whereas by external measurement of the 131I-hippurate clearance different results were obtained leading to the assumption of an increase of renal function. Only if urinary flow was free, the three methods agreed in their results. In kidneys damaged by a longer period of ureteral obstruction, these function tests yielded corresponding values only in the case of unimpaired urinary flow. Following repeated ureteral obstruction, external measurement and conventional methods no longer agreed in kidney function determination. In some cases, by external measurement renal function was determined to be higher before opening the ligation of the ureter as compared to the result achieved thereafter.
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PMID:[Animal experiment studies on the functional evaluation of hydronephrosis with non-catheter unilateral determination of 131I-hippuran clearance]. 652 73

The following experiment was performed to estimate PAH clearance of chronic unilateral and completely obstructed kidney and to explore its change during obstruction period. Thirty adult male mongrel dogs were used. Unilateral complete ureteral obstruction was made by ligation of the left ureter proximal to the bladder. After 3, 5, 10, 20 and 40 days of obstruction, an experiment was performed. Under laparotomy, the left kidney was exposed and polyethylene catheter was inserted into the renal pelvis. Intrapelvic pressure was monitored by pressure transducer. In a condition that PAH (p-aminohippurate) was constantly infused intravenously, intrapelvic urine of the obstructed kidney was exchanged for physiological saline. After the exchange, intrapelvic PAH concentration was measured at hourly intervals for 4 hours. At each midpoint of the measurements, plasma PAH concentration was measured. At the end of the experiment, the obstructed kidney was resected and pelvic capacity was measured. PAH of the obstructed pelvis increased at hourly intervals after the exchange. The result showed that the clearance ability was maintained in the completely obstructed kidney. PAH clearance values were 16.3, 13.6, 1.0, 0.9, 0.9 ml/hr/kg b.w. at 3, 5, 10, 20 and 40 days obstruction respectively. PAH clearance decreased sharply during early stage of obstruction and tended to reach a fixed low value at over 10 days of obstruction. Our experimental method seemed to be available to estimate the clearance ability of chronically, unilaterally and completely obstructed kidney.
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PMID:[An experimental study of PAH clearance in chronic unilateral and completely obstructed kidney]. 849 9

The stop flow technique was used to investigate the permeability characteristics of the dog nephron to various C(14)-labeled non-electrolytes. 12 minutes after clamping the ureter, creatinine, PAH, and C(14) compound were injected intravenously. 2 minutes later, urine samples were collected. Urea and glycerol were able to enter the tubular urine along the entire nephron at rates which were commensurate with their molecular weights. No significant movement of larger molecules (D-arabinose, D-glucose, and mannitol) could be detected. However, after administration of twenty units of pitressin, D-arabinose was able to diffuse across the distal and proximal tubular epithelium.
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PMID:Transcellular diffusion of non-electrolytes across the renal tubular epithelium. 1448 56

This report reviews the literature on the genotoxicity of mainstream tobacco smoke and cigarette smoke condensate (CSC) published since 1985. CSC is genotoxic in nearly all systems in which it has been tested, with the base/neutral fractions being the most mutagenic. In rodents, cigarette smoke induces sister chromatid exchanges (SCEs) and micronuclei in bone marrow and lung cells. In humans, newborns of smoking mothers have elevated frequencies of HPRT mutants, translocations, and DNA strand breaks. Sperm of smokers have elevated frequencies of aneuploidy, DNA adducts, strand breaks, and oxidative damage. Smoking also produces mutagenic cervical mucus, micronuclei in cervical epithelial cells, and genotoxic amniotic fluid. These data suggest that tobacco smoke may be a human germ-cell mutagen. Tobacco smoke produces mutagenic urine, and it is a human somatic-cell mutagen, producing HPRT mutations, SCEs, microsatellite instability, and DNA damage in a variety of tissues. Of the 11 organ sites at which smoking causes cancer in humans, smoking-associated genotoxic effects have been found in all eight that have been examined thus far: oral/nasal, esophagus, pharynx/larynx, lung, pancreas, myeoloid organs, bladder/ureter, uterine cervix. Lung tumors of smokers contain a high frequency and unique spectrum of TP53 and KRAS mutations, reflective of the PAH (and possibly other) compounds in the smoke. Further studies are needed to clarify the modulation of the genotoxicity of tobacco smoke by various genetic polymorphisms. These data support a model of tobacco smoke carcinogenesis in which the components of tobacco smoke induce mutations that accumulate in a field of tissue that, through selection, drive the carcinogenic process. Most of the data reviewed here are from studies of human smokers. Thus, their relevance to humans cannot be denied, and their explanatory powers not easily dismissed. Tobacco smoke is now the most extreme example of a systemic human mutagen.
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PMID:Genotoxicity of tobacco smoke and tobacco smoke condensate: a review. 1557 90