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 concentration of nine endogenous free L-alpha-amino acids (ALA, LEU, ILE, PHE, TYR, LYS, GLU, PRO, GLY) and of taurine were determined simultaneously along the nephron of the rat kidney using free-flow micropuncture techniques without altering plasma amino acid concentration or kidney function. The amount of each amino acid was determined after dansylation (14C-labelled dansyl-chloride) in the micropuncture sample followed by thinlayer chromatography. The main site of reabsorption is the proximal tubule. After 15-20% of the proximal tubule length the bulk of reabsorption has taken place (18.9 plus or minus 3.4% S.E. of the filtered load remaining). Net reabsorption continues to a small but significant extent along the distal nephron (disal tubule and collecting duct). Reabsorption of taurine is less rapid (% remaining of filtered load at the early proximal tubule 37.0 plus or minus 4.6%). The transtubular concentration ratio of all amino acids except taurine follows a homogeneous course. Under the experimental conditions of this study no distction with respect to different systems of reabsorption "neutral", "basic", "acidic", "imino-glycine") could be made.
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PMID:Amino acid reabsorption in the rat nephron. Free flow micropuncture study. 117 57

Intercalated cells (ICs) in the collecting duct and the connecting tubule (CNT) are involved in H+ secretion and HCO3- reabsorption. H+ secretion is mediated by an H(+)-adenosinetriphosphatase in the apical plasma membrane, whereas a band 3-like Cl(-)-HCO3- exchanger in the basolateral membrane is responsible for HCO3- reabsorption. Recent studies have reported that a band 3-like protein is also present in mitochondria in rabbit ICs. The purpose of this study was to establish the subcellular location of the band 3-like Cl(-)-HCO3- exchanger in rabbit ICs by electron microscopic immunocytochemistry using a monoclonal antibody, IVF12, against erythrocyte band 3 protein. Rabbit kidneys were preserved by in vivo perfusion with a paraformaldehyde-lysine-periodate solution and processed for immunocytochemistry using a horseradish peroxidase preembedding technique. Band 3 immunostaining was observed on the basolateral plasma membrane of ICs in the outer medullary collecting duct and type A cells in the cortical collecting duct (CCD) and CNT. In addition, distinct staining for band 3 was present in numerous small vesicles and in multivesicular bodies in type A ICs in the CCD and CNT. However, there was no evidence of band 3 immunostaining of mitochondria or of the apical plasma membrane in any cells of the collecting duct. These observations suggest that basolateral Cl(-)-HCO3- exchangers in type A ICs in the rabbit kidney are stored in intracellular vesicles and possibly degraded in the vascular-lysosomal system when these cells are in a resting state. The previously reported band 3 immunolabeling of mitochondria could not be confirmed.
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PMID:Intracellular band 3 immunostaining in type A intercalated cells of rabbit kidney. 137 72

Two populations of intercalated cells, type A and type B, are present in the rat cortical collecting duct (CCD). Type A cells are involved in proton secretion and contain an apical H(+)-adenosinetriphosphatase (ATPase) and a basolateral Cl(-)-HCO3- exchanger. Type B cells are believed to be involved in HCO3- secretion, which is mediated by a Cl(-)-HCO3- exchange process and is Cl- dependent. The aim of this study was to examine the morphological and immunocytochemical response of type B intercalated cells in the rat to increased delivery of Cl- to the CCD. This was accomplished by chronic infusion of a loop diuretic, bumetanide (30 mg.kg body wt-1.day-1), via an osmotic minipump, and simultaneous administration of 0.9% sodium chloride in the drinking water for 6 days. The kidneys were preserved by in vivo perfusion with a periodate-lysine-paraformaldehyde fixative and processed for horseradish peroxidase and protein A gold immunocytochemistry, using rabbit polyclonal antibodies against carbonic anhydrase II, proton ATPase, and band 3 protein. Chronic infusion of bumetanide in combination with a high salt intake was associated with significant changes in the intercalated cells. Type B cells were increased in size and exhibited numerous apical microvilli, increased basolateral membrane area, and marked cytoplasmic and basolateral labeling for H(+)-ATPase. In contrast, type A cells were small and had sparse apical microprojections. H(+)-ATPase immunolabeling was observed primarily over apical tubulovesicles, and there was decreased basolateral immunolabeling for band 3 protein and occasional labeling for band 3 in lysosome-like structures. These observations support the hypothesis that increased delivery of Cl- to the CCD is associated with stimulation of type B intercalated cells to secrete HCO3-. The observations in type A cells are consistent with the cells being in a resting or inactivated state.
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PMID:Immunocytochemical response of type A and type B intercalated cells to increased sodium chloride delivery. 153 33

The water permeability of the kidney collecting duct epithelium is regulated by vasopressin (VP)-induced recycling of water channels between an intracellular vesicular compartment and the plasma membrane of principal cells. To test whether the water channels pass through an acidic endosomal compartment during the endocytic portion of this pathway, we measured ATP-dependent acidification of FITC-dextran-labeled endosomes in isolated microsomal fractions from different regions of Brattleboro rat kidneys. Both VP-deficient controls and rat treated with exogenous VP were examined. ATP-dependent acidification was not detectable in endosomes containing water channels from distal papilla (osmotic water permeability Pf = 0.038 +/- 0.004 cm/s). In contrast, the addition of ATP resulted in a strong acidification of renal cortical endosomes (pHmin = 5.8, initial rate = 0.18-0.25 pH U/s). Acidification of cortical endosomes was reversed with nigericin and strongly inhibited by N-ethyl-maleimide. Passive proton permeability was similar and low in both cortical and papillary endosomes from rats treated or not treated with VP. The fraction of labeled endosomes present in microsomal preparations was determined by fluorescence imaging microscopy of microsomes nonspecifically bound to poly-l-lysine-coated coverslips and was 25% in cortical preparations compared to 14% (+VP) and 9% (-VP) in papillary preparations. The fraction of cortical endosomes was enriched 1.5-fold by immunoabsorption to coverslips coated with mAbs against the bovine vacuolar proton pump. In contrast, the fraction of papillary endosomes was depleted more than twofold by immunoabsorption to identical coverslips. Finally, sections of distal papilla stained with antibodies against the lysosomal glycoprotein LGP120 showed that most of the entrapped FITC-dextran did not colocalize with this lysosomal protein. These results demonstrate that vesicles which internalize water channels in kidney collecting duct principal cells lack functional proton pumps, and do not deliver the bulk of their FITC-dextran content to lysosomes. The data suggest that the principal cell contains a specialized nonacidic apical endocytic compartment which functions primarily to recycle membrane components, including water channels, to the plasma membrane.
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PMID:Endocytic vesicles from renal papilla which retrieve the vasopressin-sensitive water channel do not contain a functional H+ ATPase. 169 62

A noninvasive microscopic method was used to assess the cell specificity of vasopressin binding within the heterogeneous collecting duct. The binding of a fluorescent vasopressin analog (1-desamino-8-rhodamine-L-lysine vasopressin) to cells of the microperfused rabbit cortical collecting tubule was visualized and quantitated with image-intensified video microscopy and digital image processing. Binding to the basolateral membranes of a subpopulation of cells could be detected within 1-2 min of addition of the fluorescent analog (10 nM) to the peritubular bath. Binding could be prevented or reversed by the addition of a 10-fold excess of the native hormone, which indicates that the fluorescent analog binds specifically to vasopressin receptors. The time course of binding paralleled and slightly preceded hyperpolarization of the lumen-negative transepithelial voltage, an electrical response that is also elicited by the native hormone. Double-label experiments in which the intercalated cell population was stained with fluorescein-labeled peanut lectin revealed that binding of the vasopressin analog was localized to the remaining cell type, the principal cell. Our results support the following conclusions. First, the principal cell constitutes the primary target cell for vasopressin in the rabbit cortical collecting tubule, although the intercalated cell may possess a limited number of receptors at a density below the detection limit of this optical approach. Second, computer-enhanced video microscopy is a powerful, noninvasive method for assessing the kinetics and spatial pattern of hormone binding.
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PMID:Cell specificity of vasopressin binding in renal collecting duct: computer-enhanced imaging of a fluorescent hormone analog. 347 19

1. The changes in urinary and renal tissue composition in conscious rats were determined for up to 2 hr following the cessation of intravenous infusion of lysine vasopressin, LVP (at 60 muu./min. 100 g body wt. for 4(1/2) hr). A constant water load (4% body wt.) was maintained during and after lysine vasopressin infusion, by quantitative replacement of excreted water. In these circumstances, any changes in urinary and renal tissue composition are presumed to represent direct consequences of the rapid plasma and tissue clearance of lysine vasopressin.2. Urinary flow increased and osmolality decreased, rapidly, reaching stable values characteristic of sustained water diuresis after about 60 min.3. The steepness of the corticomedullary solute concentration gradients also decreased rapidly. Papillary Na and urea concentrations fell to values characteristic of sustained water diuresis in about 45 min.4. The changes in medullary composition were compounded of a moderate significant increase in water content, a moderate, significant decrease in Na content, and a profound decrease in urea content.5. In the eventual steady-state water diuresis, urinary outputs of Na and K were significantly lower, and of NH(4) significantly higher, than those observed in control experiments where LVP infusion was continued for the corresponding 2 hr.6. It is concluded that the diuresis following the cessation of LVP infusion is due not merely to reduced nephron permeability to water but also to a rapid reduction in the osmotic force responsible for water reabsorption from the collecting duct.
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PMID:Time course of changes in renal tissue and urinary composition after cessation of constant infusion of lysine vasopressin in the conscious, hydrated rat. 503 24

1. The changes in urinary and renal tissue composition induced by continuous, intravenous infusion of lysine-vasopressin (60 mu-u./min. 100 g body wt. until steady-state conditions prevailed) in normally hydrated, hydropaenic, saline-loaded (0.9%, w/v) and mannitol-loaded (15%, w/v) rats were determined and compared with those induced in water-loaded rats.2. Previous reports that the urinary responses to antidiuretic hormones vary both with hydration status and with concurrent solute excretion rate were confirmed.3. The data show that variations in urinary responses were accompanied by differences in the papillary responses to lysine-vasopressin.4. The results are discussed in terms of the effects of hydration and concurrent solute excretion on factors influencing (a) medullary accumulation of water and solute, (b) osmotic water reabsorption and (c) osmotic equilibration across the collecting duct; and of the effects of lysine-vasopressin on these factors.5. It is concluded that the effects of hydration and solute excretion on the antidiuretic responses to lysine-vasopressin may be interpreted by differences in (a) the medullary composition prevailing at the start and (b) any further changes in medullary composition that can be induced under the experimental circumstances.
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PMID:Influence of variations in hydration and in solute excretion of the effects of lysine-vasopressin infusion on urinary and renal tissue composition in the conscious rat. 557 32

The purpose of these studies was to elucidate the mechanism whereby collecting duct hydrogen ion secretion was augmented by acidemia. The urine minus blood PCO2 difference in alkaline urine (U-B PCO2) was used to evaluate this parameter. In dogs with a normal ECF volume, the U-B PCO2 factored was high, and there was no significant relationship between the U-B PCO2 factored for the urine bicarbonate concentration and the blood hydrogen ion concentrations unless amiloride, an agent that abolishes the transtubular potential difference, was present. In this latter case, the U-B PCO2 was a linear function of the urine bicarbonate concentration, and the U-B PCO2 factored for the urine bicarbonate concentration was directly proportional to the blood hydrogen ion concentration. To extend the pH range considerably, we used lysine to induce bicarbonaturia in dogs with an expanded ECF volume. Amiloride now caused only a small decrease in the U-B PCO2 at any urine bicarbonate concentration, and furthermore, it did not influence the linear relationship between the U-B PCO2 factored for the urine bicarbonate concentration and the blood hydrogen ion concentration. These results suggests that acidemia stimulates collecting duct hydrogen ion secretion by a mechanism that appears to be independent of the amiloride-sensitive component of the U-B PCO2. We speculate that the mechanism might involve an increased intracellular hydrogen ion concentration during acidemia.
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PMID:Studies on the mechanism whereby acidemia stimulates collecting duct hydrogen ion secretion in vivo. 628 31

Thin cortical kidney explants from newborn New Zealand rabbits were cultured in Dulbecco's MEM containing 10% fetal bovine serum. Within 24 h the explants formed globular bodies which were completely covered by a monolayered epithelium. The cells show polar differentiation and resemble the renal collecting duct epithelium. By culturing the globular bodies in Dulbecco's MEM with D-valine instead of L-valine additionally a monolayer of renal collecting duct cells was obtained. For the study of glycoprotein synthesis the globular bodies and the collecting duct monolayers were incubated with various labelled carbohydrates, protein and collagen precursors and then fractionated into coarse membrane pellets. The synthesized glycoproteins were regained in 600 x g and 12,000 x g coarse membrane fractions and extracted with Triton X 100 buffer for column chromatography and SDS-polyacrylamide electrophoresis in 6 M urea. In addition to a 85,000 d glycoprotein, a carbohydrate rich collagen like protein (apparent molecular weight in column chromatography 200,000 d, in the SDS-polyacrylamide electrophoresis 150,000 d) was found. The 150,000 d glycoprotein incorporates favorably radioactive proline, sulfate, and smaller amounts of lysine, and leucine. Compared to the 85,000 d glycoprotein a double amount of glucosamine and galactose and four fold amount of fucose was detected. The 85,000 d protein has to be ascribed as a usual glycoprotein, in contrast the 150,000 d protein shows an unusual combination of characteristics and has to be considered as a new type of renal glycoprotein.
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PMID:Cell associated glycoproteins synthesized by cultured renal tubular cells. 717 68

In contrast to results obtained in the rat kidney, studies of H+ATPase localization in the rabbit kidney have failed to demonstrate basolateral plasma membrane H+ATPase immunoreactivity in intercalated cells in the cortical collecting duct (CCD). Previous studies have relied on light microscopic immunofluorescence techniques, which have limited resolution. Therefore, the immunogold procedure was used to localize H+ATPase in rabbit collecting ducts at the ultrastructural level. Rabbit kidneys were preserved in vivo with periodate-lysine-paraformaldehyde or glutaraldehyde solutions, and samples of cortex were embedded in Lowicryl K4M. Thin sections were labeled for H+ATPase by the immunogold procedure with a rabbit polyclonal antibody against the 70-kd subunit of bovine brain H+ATPase. Three patterns of localization of H+ATPase were observed. The majority of intercalated cells in the CCD exhibited label over cytoplasmic vesicles only. In these cells, no label was associated with either the apical or basolateral plasma membranes. In a second group of cells, label for H+ATPase was observed along the basolateral plasma membrane and over cytoplasmic vesicles throughout the cell. Rarely, intercalated cells with H+ATPase label along the apical plasma membrane and over the apical cytoplasmic vesicles were observed in the CCD. In the initial collecting tubule and connecting segment, intercalated cells with either pronounced apical or basolateral plasma membrane label prevailed, whereas few cells exhibited label restricted to the cytoplasmic vesicles. In summary, in the rabbit CCD, three patterns of H+ATPase distribution exist in intercalated cells, two of which conform to published models of type A and type B intercalated cells.
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PMID:Ultrastructural localization of H+ATPase in rabbit cortical collecting duct. 802 28


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