scholarly journals Expression of multiple water channel activities in Xenopus oocytes injected with mRNA from rat kidney.

1993 ◽  
Vol 101 (6) ◽  
pp. 827-841 ◽  
Author(s):  
M Echevarria ◽  
G Frindt ◽  
G M Preston ◽  
S Milovanovic ◽  
P Agre ◽  
...  
Keyword(s):  
Water Permeability ◽  
Antisense Oligonucleotide ◽  
Xenopus Oocytes ◽  
Rat Kidney ◽  
Water Channel ◽  
Water Channels ◽  
Renal Tissue ◽  
Osmotic Water Permeability ◽  
Volume Increase ◽  
Osmotic Water

To test the hypothesis that renal tissue contains multiple distinct water channels, mRNA prepared from either cortex, medulla, or papilla of rat kidney was injected into Xenopus oocytes. The osmotic water permeability (Pf) of oocytes injected with either 50 nl of water or 50 nl of renal mRNA (1 microgram/microliter) was measured 4 d after the injection. Pf was calculated from the rate of volume increase on exposure to hyposmotic medium. Injection of each renal mRNA preparation increased the oocyte Pf. This expressed water permeability was inhibited by p-chloromercuriphenylsulfonate and had a low energy of activation, consistent with the expression of water channels. The coinjection of an antisense oligonucleotide for CHIP28 protein, at an assumed > 100-fold molar excess, with either cortex, medulla, or papilla mRNA reduced the expression of the water permeability by approximately 70, 100, and 30%, respectively. Exposure of the oocyte to cAMP for 1 h resulted in a further increase in Pf only in oocytes injected with medulla mRNA. This cAMP activation was not altered by the CHIP28 antisense oligonucleotide. These results suggest that multiple distinct water channels were expressed in oocytes injected with mRNA obtained from sections of rat kidney: (a) CHIP28 water channels in cortex and medulla, (b) cAMP-activated water channels in medulla, and (c) cAMP-insensitive water channels in papilla.

Endocytosis of water channels in rat kidney: cell specificity and correlation with in vivo antidiuresis

1990 ◽  
Vol 259 (6) ◽  
pp. C920-C932 ◽  
Author(s):  
W. I. Lencer ◽  
D. Brown ◽  
D. A. Ausiello ◽  
A. S. Verkman
Keyword(s):  
Water Permeability ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Water Channel ◽  
Water Channels ◽  
Intercalated Cells ◽  
Principal Cells ◽  
Osmotic Water ◽  
Principal And Intercalated Cells

Vasopressin action in the renal collecting duct is believed to be mediated by the cycling of water channels in principal and, possibly, intercalated cells. We used 6-carboxyfluorescein (6-CF) or fluorescein-labeled dextran (FITC-dextran) to determine the location and water permeability of endocytic vesicles from papilla and inner stripe of Brattleboro rats in different states of diuresis. Fifteen minutes after FITC-dextran infusion, fluorescent vesicles were concentrated at the apical pole of principal and intercalated cells. The osmotic water permeability (Pf) of these endosomes was measured by fluorescence quenching. In papillary endosomes, Pf was high (0.04 +/- 0.004 cm/s) when rats were in physiological states of antidiuresis or after treatment with vasopressin, 1-desamino-8-D-arginine vasopressin (DDAVP), or oxytocin; endosomes isolated from these regions of untreated animals had a low Pf. The number of papillary endosomes with high Pf increased with increasing doses of DDAVP. Endosomes from the inner stripe also had a high Pf only after vasopressin treatment. Confocal microscopy of sections of papilla showed that vasopressin significantly increased endocytosis in principal cells but had no effect on intercalated cells. Our data demonstrate that the bulk of fluorescently labeled vesicles from the papilla originate from the apical membrane of principal cells and contain water channels in their limiting membrane only when the rats are in physiological states of antidiuresis. In contrast, the majority of endocytosis in intercalated cells is not involved in water channel recycling.

Expression of Aquaporin-1 in the Peritoneal Tissues: Localization and Regulation by Hyperosmolality

2002 ◽  
Vol 22 (3) ◽  
pp. 307-315 ◽  
Author(s):  
Tomoko Ota ◽  
Michio Kuwahara ◽  
Shuling Fan ◽  
Yoshio Terada ◽  
Takashi Akiba ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Water Permeability ◽  
Water Channel ◽  
Mesothelial Cells ◽  
Scattering Method ◽  
Osmotic Water Permeability ◽  
Peritoneal Mesothelial Cells ◽  
Aquaporin 1 ◽  
Osmotic Water ◽  
Aqp1 Expression

Objective The purpose of this study was to determine the localization of the aquaporin-1 (AQP1) water channel in peritoneal tissues and the effect of hyperosmolality on the peritoneal expression and function of AQP1. Methods Immunohistochemical localization of AQP1 was identified in rat peritoneal tissues. Cultured rat peritoneal mesothelial cells (RPMCs) were exposed to hyperosmolality by adding 4% glucose to the culture medium. After 1 hour, 4 hours, 24 hours, and 48 hours, AQP1 was identified by semiquantitative immunoblot and immunocytochemistry. Osmotic water permeability was measured using a light-scattering method. Results Immunohistochemistry of rat peritoneal tissues showed the presence of AQP1 in mesothelial cells, venular endothelial cells, and capillary endothelial cells, but not in arteriole and interstitial cells. Semiquantitative immunoblot revealed that exposure to hyperosmolality significantly increased AQP1 expression after 24 hours in whole RPMC lysates (3.3-fold at 24 hours and 3.9-fold at 48 hours). Consistent with the immunoblot, osmotic water permeability of RPMC was augmented 1.7-fold and 2.7-fold after 1 hour and 24 hours, respectively, in a hyperosmotic environment. In RPMC membrane fractions, AQP1 expression was significantly increased after 1 hour of exposure to hyperosmolality (3.9-fold at 1 hour, 7.1-fold at 4 hours, and 8.7-fold at 24 hours). Immunocytochemistry of RPMCs showed that AQP1 was gradually redistributed from the perinuclear area to the peripheral cytoplasm, and then to the plasma membrane after a 1-hour hyperosmotic challenge, suggesting hyperosmolality-induced translocation of AQP1. Upregulation of AQP1 was also observed in the omentum of rats loaded intraperitoneally with hyperosmotic dialysate every day for 10 weeks. Conclusion AQP1 is widely distributed in the peritoneal cavity and may provide the major aqueous pathway across the peritoneal barrier. In addition, our findings suggested that hyperosmolality increases AQP1-dependent water permeability in peritoneal tissues by regulating the translocation and synthesis of AQP1 protein.

scholarly journals Relative CO2/NH3 selectivities of mammalian aquaporins 0–9

2013 ◽  
Vol 304 (10) ◽  
pp. C985-C994 ◽  
Author(s):  
R. Ryan Geyer ◽  
Raif Musa-Aziz ◽  
Xue Qin ◽  
Walter F. Boron
Keyword(s):  
Plasma Membrane ◽  
Water Permeability ◽  
Xenopus Oocytes ◽  
Video Microscopy ◽  
Osmotic Water Permeability ◽  
Permeability Ratio ◽  
Diverse Range ◽  
Surface Ph ◽  
Aquaporin 1 ◽  
Osmotic Water

Previous work showed that aquaporin 1 (AQP1), AQP4-M23, and AQP5 each has a characteristic CO2/NH3 and CO2/H2O permeability ratio. The goal of the present study is to characterize AQPs 0–9, which traffic to the plasma membrane when heterologously expressed in Xenopus oocytes. We use video microscopy to compute osmotic water permeability ( Pf) and microelectrodes to record transient changes in surface pH (ΔpHS) caused by CO2 or NH3 influx. Subtracting respective values for day-matched, H2O-injected control oocytes yields the channel-specific values Pf* and ΔpHS*. We find that Pf* is significantly >0 for all AQPs tested except AQP6. (ΔpHS*)CO2 is significantly >0 for AQP0, AQP1, AQP4-M23, AQP5, AQP6, and AQP9. (ΔpHS*)NH3 is >0 for AQP1, AQP3, AQP6, AQP7, AQP8, and AQP9. The ratio (ΔpHS*)CO2/ Pf* falls in the sequence AQP6 (∞) > AQP5 > AQP4-M23 > AQP0 ≅ AQP1 ≅ AQP9 > others (0). The ratio (ΔpHS*)NH3/ Pf* falls in the sequence AQP6 (∞) > AQP3 ≅ AQP7 ≅ AQP8 ≅ AQP9 > AQP1 > others (0). Finally, the ratio (ΔpHS*)CO2/(−ΔpHS*)NH3 falls in the sequence AQP0 (∞) ≅ AQP4-M23 ≅ AQP5 > AQP6 > AQP1 > AQP9 > AQP3 (0) ≅ AQP7 ≅ AQP8. The ratio (ΔpHS*)CO2/(−ΔpHS*)NH3 is indeterminate for both AQP2 and AQP4-M1. In summary, we find that mammalian AQPs exhibit a diverse range of selectivities for CO2 vs. NH3 vs. H2O. As a consequence, by expressing specific combinations of AQPs, cells could exert considerable control over the movements of each of these three substances.

scholarly journals Colon water transport in transgenic mice lacking aquaporin-4 water channels

2000 ◽  
Vol 279 (2) ◽  
pp. G463-G470 ◽  
Author(s):  
Kasper S. Wang ◽  
Tonghui Ma ◽  
Ferda Filiz ◽  
A. S. Verkman ◽  
J. Augusto Bastidas
Keyword(s):  
Water Content ◽  
Water Transport ◽  
Water Permeability ◽  
Basolateral Membrane ◽  
Distal Colon ◽  
Water Channels ◽  
Proximal Colon ◽  
Aquaporin 4 ◽  
Osmotic Water Permeability ◽  
Osmotic Water

Transgenic null mice were used to test the hypothesis that water channel aquaporin-4 (AQP4) is involved in colon water transport and fecal dehydration. AQP4 was immunolocalized to the basolateral membrane of colonic surface epithelium of wild-type (+/+) mice and was absent in AQP4 null (−/−) mice. The transepithelial osmotic water permeability coefficient ( P f) of in vivo perfused colon of +/+ mice, measured using the volume marker 14C-labeled polyethylene glycol, was 0.016 ± 0.002 cm/s. P f of proximal colon was greater than that of distal colon (0.020 ± 0.004 vs. 0.009 ± 0.003 cm/s, P < 0.01). P f was significantly lower in −/− mice when measured in full-length colon (0.009 ± 0.002 cm/s, P< 0.05) and proximal colon (0.013 ± 0.002 cm/s, P< 0.05) but not in distal colon. There was no difference in water content of cecal stool from +/+ vs. −/− mice (0.80 ± 0.01 vs. 0.81 ± 0.01), but there was a slightly higher water content in defecated stool from −/− mice (0.68 ± 0.01 vs. 0.65 ± 0.01, P < 0.05). Despite the differences in water permeability with AQP4 deletion, theophylline-induced secretion was not impaired (50 ± 9 vs. 51 ± 8 μl · min−1 · g−1). These results provide evidence that transcellular water transport through AQP4 water channels in colonic epithelium facilitates transepithelial osmotic water permeability but has little or no effect on colonic fluid secretion or fecal dehydration.

Functional analysis of aquaporin-2 mutants associated with nephrogenic diabetes insipidus by yeast expression

1999 ◽  
Vol 277 (5) ◽  
pp. F734-F741 ◽  
Author(s):  
Itsuki Shinbo ◽  
Kiyohide Fushimi ◽  
Michihiro Kasahara ◽  
Kazushi Yamauchi ◽  
Sei Sasaki ◽  
...  
Keyword(s):  
Diabetes Insipidus ◽  
Water Permeability ◽  
Nephrogenic Diabetes Insipidus ◽  
Water Channel ◽  
Osmotic Water Permeability ◽  
Wild Type ◽  
The Third ◽  
Aquaporin 2 ◽  
Channel Water ◽  
Osmotic Water

Mutations of aquaporin-2 (AQP2) vasopressin water channel cause nephrogenic diabetes insipidus (NDI). It has been suggested that impaired routing of AQP2 mutants to the plasma membrane causes the disease; however, no determinations have been made of mutation-induced alterations of AQP2 channel water permeability. To address this issue, a series of AQP2 mutants were expressed in yeast, and the osmotic water permeability ( Pf) of the isolated vesicles was measured. Wild-type and mutant AQP2 were expressed equally well in vesicles. Pfof the vesicles containing wild-type AQP2 was 22 times greater than that of the control, which was sensitive to mercury and weakly dependent on the temperature. Pfmeasurements and mercury inhibition examinations suggested that mutants L22V and P262L are fully functional, whereas mutants N68S, R187C, and S216P are partially functional. In contrast, mutants N123D, T125M, T126M, A147T, and C181W had very low water permeability. Our results suggest that the structure between the third and fifth hydrophilic loops is critical for the functional integrity of the AQP2 water channel and that disruption of AQP2 water permeability by mutations may cause NDI.

scholarly journals Osmotic water permeability of human red cells.

1981 ◽  
Vol 77 (5) ◽  
pp. 549-570 ◽  
Author(s):  
T C Terwilliger ◽  
A K Solomon
Keyword(s):  
Systematic Error ◽  
Water Permeability ◽  
Perturbation Technique ◽  
Mean Value ◽  
Red Cells ◽  
Osmotic Water Permeability ◽  
Osmotic Water ◽  
New Perturbation ◽  
The Relationship ◽  
Human Red Cells

The osmotic water permeability of human red cells has been reexamined with a stopped-flow device and a new perturbation technique. Small osmotic gradients are used to minimize the systematic error caused by nonlinearities in the relationship between cell volume and light scattering. Corrections are then made for residual systematic error. Our results show that the hydraulic conductivity, Lp, is essentially independent of the direction of water flow and of osmolality in the range 184-365 mosM. the mean value of Lp obtained obtained was 1.8 +/- 0.1 (SEM) X 10-11 cm3 dyne -1 s-1.

Progesterone inhibition of water permeability in Bufo arenarum oocytes and urinary bladder

1996 ◽  
Vol 270 (5) ◽  
pp. F880-F885 ◽  
Author(s):  
P. Ford ◽  
G. Amodeo ◽  
C. Capurro ◽  
C. Ibarra ◽  
R. Dorr ◽  
...  
Keyword(s):  
Urinary Bladder ◽  
Xenopus Laevis ◽  
Water Permeability ◽  
Water Channel ◽  
Water Channels ◽  
Toad Urinary Bladder ◽  
Osmotic Permeability ◽  
Bufo Arenarum ◽  
Mrna Extraction

The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have water channels (WC). We now report that the injection of the mRNA from BAO into the oocytes from XLO increased their water osmotic permeability (Pi) (reduced by 0.3 mM HgCl2 and reversed by 5 mM beta-mercaptoethanol). A 30-min challenge with progesterone induced, 18 h later, a reduction of the mercury-sensitive fraction of Pf in the BAO (but not in XLO). The mRNA from BAO pretreated with progesterone lost its capacity to induce WC in the XLO, but the hormone did not affect the expression of the WC in XLO previously injected with the mRNA from BAO. Pf was also measured in urinary bladders of BAO. Eighteen hours after a challenge with progesterone, a reduction in the hydrosmotic response to oxytocin was observed. Finally, the mRNA from the urinary bladder of BAO was injected into XLO. An increase in Pf was observed. This was not the case if, before the mRNA extraction, the bladders were treated with progesterone. We conclude that the BAO WC share progesterone sensitivity with the oxytocin-regulated water channel present in the toad urinary bladder.

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