The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
A S Verkman - One of the best experts on this subject based on the ideXlab platform.
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transcellular water flow modulates water channel exocytosis and endocytosis in Kidney Collecting Tubule
Journal of Clinical Investigation, 1991Co-Authors: Michio Kuwahara, Fumiaki Marumo, A S VerkmanAbstract:Abstract The regulation of osmotic water permeability (Pf) by vasopressin (VP) in Kidney Collecting Tubule involves the exocytic-endocytic trafficking of vesicles containing water channels between an intracellular compartment and apical plasma membrane. To examine effects of transcellular water flow on vesicle movement, Pf was measured with 1-s time resolution in the isolated perfused rabbit cortical Collecting Tubule in response to addition and removal of VP (250 microU/ml) in the presence of bath greater than lumen (B greater than L), lumen greater than bath (L greater than B), and lumen = bath (L = B) osmolalities. With VP addition, Pf increased from 12 to 240-270 x 10(-4) cm/s (37 degrees C) in 10 min. At 1 min, Pf was approximately 70 x 10(-4) cm/s for B greater than L, L greater than B, and L = B conditions. At later times, Pf increased fastest for L greater than B and slowest for B greater than L osmolalities; at 5 min, Pf was 250 x 10(-4) cm/s (L greater than B) and 158 x 10(-4) cm/s (B greater than L). With VP removal, Pf returned to pre-VP levels at the fastest rate for B greater than L and the slowest rate for L greater than B osmolalities; at 30 min, Pf was 65 x 10(-4) cm/s (B greater than L) and 183 x 10(-4) cm/s (L greater than B). For a series of osmotic gradients of different magnitudes and directions, the rates of Pf increase and decrease were dependent upon the magnitude of transcellular volume flow; control studies showed that paracellular water flux, asymmetric transcellular water pathways, or changes in cell volume could not account for the data. VP-dependent endocytosis was measured by apical uptake of rhodamine-dextran; in paired studies where the same Tubule was used for + and - gradients, B greater than L and L greater than B osmolalities gave 168% and 82% of uptake measured with no gradient. In contrast, endocytosis in proximal Tubule was not dependent on gradient direction. These data provide evidence that transcellular volume flow modulates the vasopressin-dependent cycling of vesicles containing water channels, suggesting a novel driving mechanism to aid or oppose the targeted, hormonally directed movement of subcellular membranes.
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Relationship between vasopressin-sensitive water transport and plasma membrane fluidity in Kidney Collecting Tubule.
The American journal of physiology, 1991Co-Authors: K Fushimi, A S VerkmanAbstract:The role of plasma membrane fluidity in the regulation of Kidney Tubule water permeability has been uncertain. We have used new methods to image the fluorescence anisotropy of fluidity-sensitive fluorophores (Fushimi, Dix, and Verkman. Biophys. J. 57: 241-254, 1990) to quantitate membrane fluidity in cells of the vasopressin-sensitive cortical Collecting Tubule (CCT) and water-impermeable cortical thick ascending limb (CTAL). Isolated Tubule segments from rabbit Kidney were perfused in vitro, and apical or basolateral plasma membranes were stained with trimethylammonium diphenylhexatriene (TMA-DPH). TMA-DPH anisotropy (r) was imaged quantitatively by an epifluorescence microscope equipped with rotatable polarizers; TMA-DPH nanosecond lifetime (tau) was measured by flash-lamp excitation and gated photomultiplier detection. In CCT, apical membrane r (0.254 +/- 0.003) was similar to basolateral r (0.252 +/- 0.005). Serosal vasopressin at a dose that increased water permeability greater than 10-fold (250 microU/ml) did not affect apical membrane r (delta r = 0.002 +/- 0.003; 7 Tubules). A 0.002 change in r was less than that produced by a 2 degrees C temperature variation. In CTAL, apical membrane r was 0.249 +/- 0.002, similar to r from basolateral membrane of proximal Tubule (0.24), but much less than that of proximal Tubule apical membrane (0.29). These results establish methodology to quantitate fluidity in intact Kidney Tubule segments and provide the first measurements of plasma membrane fluidity in CTAL and CCT. Our results suggest that regulation of bulk membrane fluidity in CCT apical membrane is not a component of the hydrosmotic action of vasopressin and that low apical membrane fluidity is not responsible for the low water and NH3 permeabilities in CTAL.
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relationship between vasopressin sensitive water transport and plasma membrane fluidity in Kidney Collecting Tubule
American Journal of Physiology-cell Physiology, 1991Co-Authors: Kiyohide Fushimi, A S VerkmanAbstract:The role of plasma membrane fluidity in the regulation of Kidney Tubule water permeability has been uncertain. We have used new methods to image the fluorescence anisotropy of fluidity-sensitive fl...
Kiyohide Fushimi - One of the best experts on this subject based on the ideXlab platform.
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cloning and expression of apical membrane water channel of rat Kidney Collecting Tubule
Nature, 1993Co-Authors: Kiyohide Fushimi, Shinichi Uchida, Y Hara, Yukio Hirata, Fumiaki Marumo, Sei SasakiAbstract:CONCENTRATING urine is mandatory for most mammals to prevent water loss from the body. Concentrated urine is produced in response to vasopressin by the transepithelial recovery of water from the lumen of the Kidney Collecting Tubule through highly water-permeable membranes1,2. In this nephron segment, vaso-pressin regulates water permeability by endo- and exocytosis of water channels from or to the apical membrane3,4. CHIP28 is a water channel in red blood cells and the Kidney proximal Tubule5, but it is not expressed in the Collecting Tubule6. Here we report the cloning of the complementary DNA for WCH-CD, a water channel of the apical membrane of the Kidney Collecting Tubule. WCH-CD is 42% identical in amino-acid sequence to CHIP28. WCH-CD transcripts are detected only in the Collecting Tubule of the Kidney. Immunohistochemically, WCH-CD is localized to the apical region of the Kidney Collecting Tubule cells. Expression of WCH-CD in Xenopus oocytes markedly increases osmotic water permeability. The functional expression and the limited localization of WCH-CD to the apical region of the Kidney Collecting Tubule suggest that WCH-CD is the vasopressin-regulated water channel.
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relationship between vasopressin sensitive water transport and plasma membrane fluidity in Kidney Collecting Tubule
American Journal of Physiology-cell Physiology, 1991Co-Authors: Kiyohide Fushimi, A S VerkmanAbstract:The role of plasma membrane fluidity in the regulation of Kidney Tubule water permeability has been uncertain. We have used new methods to image the fluorescence anisotropy of fluidity-sensitive fl...
Sei Sasaki - One of the best experts on this subject based on the ideXlab platform.
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cloning and expression of apical membrane water channel of rat Kidney Collecting Tubule
Nature, 1993Co-Authors: Kiyohide Fushimi, Shinichi Uchida, Y Hara, Yukio Hirata, Fumiaki Marumo, Sei SasakiAbstract:CONCENTRATING urine is mandatory for most mammals to prevent water loss from the body. Concentrated urine is produced in response to vasopressin by the transepithelial recovery of water from the lumen of the Kidney Collecting Tubule through highly water-permeable membranes1,2. In this nephron segment, vaso-pressin regulates water permeability by endo- and exocytosis of water channels from or to the apical membrane3,4. CHIP28 is a water channel in red blood cells and the Kidney proximal Tubule5, but it is not expressed in the Collecting Tubule6. Here we report the cloning of the complementary DNA for WCH-CD, a water channel of the apical membrane of the Kidney Collecting Tubule. WCH-CD is 42% identical in amino-acid sequence to CHIP28. WCH-CD transcripts are detected only in the Collecting Tubule of the Kidney. Immunohistochemically, WCH-CD is localized to the apical region of the Kidney Collecting Tubule cells. Expression of WCH-CD in Xenopus oocytes markedly increases osmotic water permeability. The functional expression and the limited localization of WCH-CD to the apical region of the Kidney Collecting Tubule suggest that WCH-CD is the vasopressin-regulated water channel.
Fumiaki Marumo - One of the best experts on this subject based on the ideXlab platform.
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cloning and expression of apical membrane water channel of rat Kidney Collecting Tubule
Nature, 1993Co-Authors: Kiyohide Fushimi, Shinichi Uchida, Y Hara, Yukio Hirata, Fumiaki Marumo, Sei SasakiAbstract:CONCENTRATING urine is mandatory for most mammals to prevent water loss from the body. Concentrated urine is produced in response to vasopressin by the transepithelial recovery of water from the lumen of the Kidney Collecting Tubule through highly water-permeable membranes1,2. In this nephron segment, vaso-pressin regulates water permeability by endo- and exocytosis of water channels from or to the apical membrane3,4. CHIP28 is a water channel in red blood cells and the Kidney proximal Tubule5, but it is not expressed in the Collecting Tubule6. Here we report the cloning of the complementary DNA for WCH-CD, a water channel of the apical membrane of the Kidney Collecting Tubule. WCH-CD is 42% identical in amino-acid sequence to CHIP28. WCH-CD transcripts are detected only in the Collecting Tubule of the Kidney. Immunohistochemically, WCH-CD is localized to the apical region of the Kidney Collecting Tubule cells. Expression of WCH-CD in Xenopus oocytes markedly increases osmotic water permeability. The functional expression and the limited localization of WCH-CD to the apical region of the Kidney Collecting Tubule suggest that WCH-CD is the vasopressin-regulated water channel.
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transcellular water flow modulates water channel exocytosis and endocytosis in Kidney Collecting Tubule
Journal of Clinical Investigation, 1991Co-Authors: Michio Kuwahara, Fumiaki Marumo, A S VerkmanAbstract:Abstract The regulation of osmotic water permeability (Pf) by vasopressin (VP) in Kidney Collecting Tubule involves the exocytic-endocytic trafficking of vesicles containing water channels between an intracellular compartment and apical plasma membrane. To examine effects of transcellular water flow on vesicle movement, Pf was measured with 1-s time resolution in the isolated perfused rabbit cortical Collecting Tubule in response to addition and removal of VP (250 microU/ml) in the presence of bath greater than lumen (B greater than L), lumen greater than bath (L greater than B), and lumen = bath (L = B) osmolalities. With VP addition, Pf increased from 12 to 240-270 x 10(-4) cm/s (37 degrees C) in 10 min. At 1 min, Pf was approximately 70 x 10(-4) cm/s for B greater than L, L greater than B, and L = B conditions. At later times, Pf increased fastest for L greater than B and slowest for B greater than L osmolalities; at 5 min, Pf was 250 x 10(-4) cm/s (L greater than B) and 158 x 10(-4) cm/s (B greater than L). With VP removal, Pf returned to pre-VP levels at the fastest rate for B greater than L and the slowest rate for L greater than B osmolalities; at 30 min, Pf was 65 x 10(-4) cm/s (B greater than L) and 183 x 10(-4) cm/s (L greater than B). For a series of osmotic gradients of different magnitudes and directions, the rates of Pf increase and decrease were dependent upon the magnitude of transcellular volume flow; control studies showed that paracellular water flux, asymmetric transcellular water pathways, or changes in cell volume could not account for the data. VP-dependent endocytosis was measured by apical uptake of rhodamine-dextran; in paired studies where the same Tubule was used for + and - gradients, B greater than L and L greater than B osmolalities gave 168% and 82% of uptake measured with no gradient. In contrast, endocytosis in proximal Tubule was not dependent on gradient direction. These data provide evidence that transcellular volume flow modulates the vasopressin-dependent cycling of vesicles containing water channels, suggesting a novel driving mechanism to aid or oppose the targeted, hormonally directed movement of subcellular membranes.
M. Svelto - One of the best experts on this subject based on the ideXlab platform.
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Aquaporin-CHIP-related protein in frog urinary bladder: Localization by confocal microscopy
The Journal of Membrane Biology, 1995Co-Authors: G. Calamita, M. Grazia Mola, P. Gounon, M. Jouve, J. Bourguet, M. SveltoAbstract:Aquaporin CHIP, a 28 kDa channel forming protein, has been proposed to function as water channel in both erythrocyte and Kidney proximal Tubule. Recently, we have reported that in frog urinary bladder, a model of the Kidney Collecting Tubule, polyclonal antibodies against human erythrocyte CHIP recognize and immunoprecipitate a 30 kDa protein from the epithelial cell homogenate. In the present work confocal fluorescence microscopy was used to determine the cellular and subcellular localization of CHIP28-like proteins in the urinary epithelium. A clear labeling of the apical border was found after Triton X-100 permeabilization. The labeling was distributed throughout the apical domain and not restricted to specific domains of the membrane. The staining was also present in the deeper confocal sections where the fluorescence seems to be localized at the cellular contour. No difference in the labeling patterns was observed between resting and ADH-treated bladder. Specificity of the staining was confirmed by the absence of the labeling pattern when antiserum was preadsorbed on CHIP28 protein immobilized on Immobilon P stripes. Our results suggest that CHIP-like proteins are not proteins inserted in the apical membrane during the antidiuretic response. Moreover, we do not know whether the labeling was due to the presence of CHIP28 itself or an as-yet-unidentified protein sharing immunological analogies with aquaporin CHIP.
