Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distribution and activities of several oxidative enzymes in the urinary apparatus of five freshwater fish species (river lamprey, lobe finned eel, Prussian carp, rainbow trout and three-spined stickleback) have been studied. Species were selected from three main taxonomic groups: Cyclostomata, Polypterini, Teleostei. Distinctly positive enzyme reactions were only found in the tubular elements of the kidney and the collecting duct-archinephric duct system, with the exception of the generally weak staining intensities of lactate dehydrogenase. The distal tubule normally showed strong to very strong reactions for most of the enzymes investigated. In the epithelial cells of the collecting tubule-collecting duct system, stronger reactions were observed for most of the mitochondrial-bound enzymes, especially succinate dehydrogenase and NADH-diaphorase. For these enzymes, the cells of the archinephric duct reacted strongly positive in Lampetra, Carassius and Gasterosteus. The enzyme patterns of various types of urinary tubules and ducts are compared with results of several morphological studies. In addition, the histochemical findings are discussed in relation to kidney function in different vertebrate groups.
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PMID:Oxidative enzymes in the urinary apparatus of several freshwater fishes. 43 99

In order to study the mechanisms involved in the regulation of renal inner medullary sorbitol content, collecting duct cells were isolated from rat inner medulla and the effect of extracellular osmolarity on sorbitol synthesis and sorbitol content was investigated. Cells isolated at 300 mosmol/l and incubated up to 24 h as primary cultures in 300 mosmol/l media or in media made 600 mosmol/l by the addition of 150 mM NaCl showed no difference in total synthesis. Intracellular sorbitol content was, however, 2.3-fold higher in the cells kept in the higher osmotic medium. Cells isolated at 600 mosmol/l released sorbitol about 8 times faster when transferred into hypoosmotic medium (300 mosmol/l) than when transferred into isoosmotic (600 mosmol/l) media. Cells exposed to hyperosmotic media (900 mosmol/l with NaCl) maintained a higher intracellular sorbitol content than cells incubated in isoosmotic media. Changes of intracellular sorbitol content could not be attributed entirely to cell lysis--as demonstrated by determination of cellular content of lactate and lactate dehydrogenase. The alteration in sorbitol membrane permeability was reversible and was only observed when poorly permeable solutes (such as NaCl and sucrose) were used for the experiments, changes in urea elicited no effect. It is proposed that rapid changes in membrane permeability to sorbitol play an important role in the adjustment of intracellular sorbitol concentration in inner medullary collecting duct cells to changes in extracellular osmolarity.
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PMID:Intracellular sorbitol content in isolated rat inner medullary collecting duct cells. Regulation by extracellular osmolarity. 275 72

Renal oncocytomas, which have previously been shown to originate from the collecting duct system, were induced in male Sprague-Dawley rats by oral administration of N-nitrosomorpholine (NNM) for 7 weeks. The expression of glucose transporter isoforms GLUT1 and GLUT2, and of several enzymes involved in glucose metabolism [hexokinase (HK), pyruvate kinase (PK), lactate dehydrogenase (LDH), malate dehydrogenase (MDH)] were studied by cytochemical approaches in serial cryostat sections of the kidney 12, 23 and 34 weeks after withdrawal of NNM. Oncocytic tubules connected with collecting ducts were first observed 23 weeks, and oncocytomas 34 weeks after withdrawal. The cytochemical pattern of oncocytic tubules and oncocytomas was similar, but differed markedly from that of normal collecting ducts in nearly all variables studied; expression of GLUT1 and hexokinase I proteins were strongly increased; activities of HK, PK and MDH were elevated, while LDH activity was reduced. These results suggest that oncocytic transformation is associated with fundamental changes in energy metabolism which differ from those in cell lineages leading to other types of renal cell tumours, such as clear/acidophilic and basophilic cell tumours. The characteristic over-expression of GLUT1 may be used as a diagnostic criterion for the discrimination between oncocytes and acidophilic (granular) cells in clear/acidophilic renal cell tumours which show a reduced expression of this glucose transporter protein.
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PMID:Over-expression of glucose transporter isoform GLUT1 and hexokinase I in rat renal oncocytic tubules and oncocytomas. 792 15

Although heat stress proteins (HSPs) mediate thermotolerance, the cellular targets of thermal injury and mechanisms of acquired cytoprotection are unknown. To describe the metabolic effects of hyperthermia and the potential mechanisms of thermotolerance, the following were measured in inner medullary collecting duct cells after a 43 degrees C and/or a 50 degrees C thermal insult: 1) state III mitochondrial respiration (SIII MR), 2) glycolytic rate, 3) lactate dehydrogenase activity, 4) membrane permeability, and 5) HSP 72 content. Compared with controls incubated at 37 degrees C, cells heated to 50 degrees C showed a 30 and 50% reduction in glycolysis and SIII MR, respectively. After heating to 50 degrees C, the cell membrane remained intact and immunoreactive HSP 72 was not detected. In contrast, heating to 43 degrees C induced accumulation of HSP 72 and transiently increased both SIII MR and glycolysis. In addition, prior exposure to 43 degrees C completely prevented the fall in SIII MR and glycolysis anticipated with a subsequent 50 degrees C insult. Cytoprotection gradually diminished over several days and correlated with the disappearance of HSP 72. Preservation of oxidative and anaerobic metabolism associated with HSPs may be important in developing resistance to thermal injury.
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PMID:Heat stress protein-associated cytoprotection of inner medullary collecting duct cells from rat kidney. 821 91

To evaluate the effect of cyclosporine A (CyA) at high concentrations (10(-4) and 10(-5) M) and the influence of endothelin-1 (ET-1) at physiological and pharmacological concentrations (10(-14) to 10(-6) M) on epithelial cell function, LLC-PK1 cells were studied as a model of the proximal tubule and MDCK cells as a model of the distal tubule/collecting duct. CyA caused time- and concentration-dependent acute toxicity. In LLC-PK1 cells, CyA caused a decrease in transepithelial resistance, indicating a loss of cell contacts, a release of lactate dehydrogenase (LDH) and villin into the supernatant, suggesting destruction of the apical membrane with loss of brush border, and finally release of uvomorulin, suggesting a disruption of the cell-cell adhesion, the zonula adherens. DNA synthesis, as evaluated by bromodeoxyuridine (BrdU) incorporation, was significantly affected at > or = 10(-5) M CyA. The toxicity of CyA was higher when given from the apical rather than the basolateral compartment. ET-1 alone was without effect, but in combination with CyA, ET-1 significantly enhanced toxicity. The ET-1 effect was partially inhibitable by an ET(B), but not an ET(A), antagonist. Immunofluorescence for alpha-catenin, another protein of the zonula adherens, demonstrated no change in polarity for this protein, and immunoprecipitation of the complex indicated relative stability of the zonula adherens despite loss of cadherin into the supernatant. In MDCK cells the effects were different. CyA was not associated with LDH release, but with an increase in transepithelial resistance, indicating increased paracellular resistance. Morphological alterations were significantly less, but BrdU incorporation was decreased. This pattern of toxicity is compatible with a direct toxic effect of CyA on cells of the proximal tubule, with predominant morphological destruction of the cells, with concomitant proximal tubular dysfunction, and a functional alteration in cells of the distal tubule associated with increased paracellular resistance, which may lead to solute and water loss.
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PMID:Tubular toxicity of cyclosporine A and the influence of endothelin-1 in renal cell culture models (LLC-PK1 and MDCK). 943 65