The molecular structure of the antidiuretic hormone elicited water channel

1993 ◽  
Vol 7 (5) ◽  
pp. 680-684 ◽  
Author(s):  
H. W. Harris ◽  
A. Paredes ◽  
M. L. Zeidel
Keyword(s):  
Molecular Structure ◽  
Antidiuretic Hormone ◽  
Water Channel

scholarly journals Molecular structure of the water channel through aquaporin CHIP. The hourglass model.

1994 ◽  
Vol 269 (20) ◽  
pp. 14648-14654 ◽  
Author(s):  
J.S. Jung ◽  
G.M. Preston ◽  
B.L. Smith ◽  
W.B. Guggino ◽  
P. Agre
Keyword(s):  
Molecular Structure ◽  
Water Channel ◽  
Hourglass Model

Oxytocin as an antidiuretic hormone. I. Concentration dependence of action

1995 ◽  
Vol 269 (1) ◽  
pp. F70-F77 ◽  
Author(s):  
C. L. Chou ◽  
S. R. DiGiovanni ◽  
R. Mejia ◽  
S. Nielsen ◽  
M. A. Knepper
Keyword(s):  
Antidiuretic Hormone ◽  
Water Permeability ◽  
Water Channel ◽  
Fold Increase ◽  
Brattleboro Rats ◽  
Sprague Dawley ◽  
Water Restriction ◽  
Sprague Dawley Rats ◽  
Osmotic Water ◽  
Response To Water

Circulating concentrations of oxytocin increase to 10-40 pM in rats in response to osmotic stimuli, suggesting that oxytocin could play a role in regulation of water balance. The present studies tested whether oxytocin at such concentrations increases osmotic water permeability (Pf) in isolated perfused terminal inner medullary collecting ducts (IMCD). In IMCD segments from Sprague-Dawley rats, 20 pM oxytocin added to the peritubular bath caused a two- to threefold increase in Pf, whereas 200 pM oxytocin increased Pf by five- to sixfold (n = 8, P < 0.01). IMCD from Brattleboro rats, which manifest central diabetes insipidus, exhibited a 2.8-fold increase in Pf in response to 20 pM oxytocin and a 4.7-fold increase in response to 200 pM oxytocin. However, in Brattleboro rats, the response to 20 pM oxytocin was dependent on prior water restriction of the rats. Immunoblotting showed no change in the expression of the aquaporin-CD water channel in Brattleboro rats in response to water restriction. Nevertheless, immunofluorescence studies of inner medullary tissue from Brattleboro rats revealed a marked redistribution of the aquaporin-CD water channels to a predominantly apical and subapical localization in IMCD cells in response to water restriction, similar to the redistribution seen in response to vasopressin. Mathematical modeling studies revealed that the measured increase in Pf in response to oxytocin is sufficient to generate a concentrated urine. We conclude that oxytocin can function physiologically as an antidiuretic hormone, mimicking the short-term action of vasopressin on water permeability, albeit with somewhat lower potency.

High proton flux through membranes containing antidiuretic hormone water channels

1990 ◽  
Vol 259 (2) ◽  
pp. F366-F371 ◽  
Author(s):  
H. W. Harris ◽  
D. Kikeri ◽  
A. Janoshazi ◽  
A. K. Solomon ◽  
M. L. Zeidel
Keyword(s):  
Antidiuretic Hormone ◽  
Water Channel ◽  
Granular Cell ◽  
Water Channels ◽  
Proton Flux ◽  
Toad Urinary Bladder ◽  
High Proton ◽  
Mixing Techniques ◽  
Apical Membranes ◽  
Endocytic Vesicles

Antidiuretic hormone (ADH) stimulation of toad urinary bladder granular cells causes simultaneous increases in transepithelial water and H+ permeabilities (PF and PH+, respectively), suggesting that ADH-elicited water channels inserted into granular cell apical membranes might be permeable to both water and H+. We have previously used self-quenching fluorophores entrapped within endocytic vesicles selectively retrieved from water-permeable apical membranes to measure vesicle PF. The membranes of these vesicles possess an extremely high PF such that our measurements provide only minimum estimates of vesicle PF and have limited our ability to quantitate the properties of ADH water channels. We therefore quantitated vesicle PH+ using similar rapid mixing techniques. Vesicle PH+ was 5.1 +/- 0.5 x 10(-3) cm/s. Activation energy of this process was 3.6 +/- 0.6 kcal/mol, indicative of H+ flux through an aqueous channel. The mercurial reagent, para-chloromercuribenzenesulfonate (PCMBS), which inhibits ADH-stimulated transepithelial PF in intact bladders by 50-60%, inhibited vesicle PH+ by 55%. N-Ethylmaleimide and phloretin, which do not alter ADH-stimulated PF, did not affect vesicle PH+. We conclude that membranes containing ADH water channels possess substantial PH+ that likely reflects proton flux through water channels. The apparent high PH+ of the ADH water channel may have important implications for intracellular trafficking of these water channels in ADH-responsive epithelial cells.

Regulated exocytosis: Renal Aquaporin-2 3D Vesicular Network Organization and Association with F-actin

2021 ◽  
Author(s):  
Mikkel R. Holst ◽  
Louis Gammelgaard ◽  
Jesse Aaron ◽  
Frédéric H. Login ◽  
Sampavi Rajkumar ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Antidiuretic Hormone ◽  
Collecting Duct ◽  
Water Channel ◽  
Urine Concentration ◽  
Apical Plasma Membrane ◽  
Aquaporin 2 ◽  
3D Network ◽  
Vesicle Exocytosis ◽  
A Cell

Regulated vesicle exocytosis is a key response to extracellular stimuli in diverse physiological processes; including hormone regulated short-term urine concentration. In the renal collecting duct, the water channel aquaporin-2 localizes to the apical plasma membrane as well as small, sub-apical vesicles. In response to stimulation with the antidiuretic hormone, arginine vasopressin, aquaporin-2 containing vesicles fuse with the plasma membrane, which increases collecting duct water reabsorption and thus, urine concentration. The nano-scale size of these vesicles has limited analysis of their 3D organization. Using a cell system combined with 3D super resolution microscopy, we provide the first direct analysis of the 3D network of aquaporin-2 containing exocytic vesicles in a cell culture system. We show that aquaporin-2 vesicles are 43 ± 3nm in diameter, a size similar to synaptic vesicles, and that one fraction of AQP2 vesicles localized with the sub-cortical F-actin layer and the other localized in between the F-actin layer and the plasma membrane. Aquaporin-2 vesicles associated with F-actin and this association was enhanced in a serine 256 phospho-mimic of aquaporin-2, whose phosphorylation is a key event in antidiuretic hormone-mediated aquaporin-2 vesicle exocytosis.

Cytoplasmic dilution induces antidiuretic hormone water channel retrieval in toad urinary bladder

1992 ◽  
Vol 263 (1) ◽  
pp. F163-F170 ◽  
Author(s):  
H. W. Harris ◽  
B. Botelho ◽  
M. L. Zeidel ◽  
K. Strange
Keyword(s):  
Urinary Bladder ◽  
Antidiuretic Hormone ◽  
Apical Cell ◽  
Water Channel ◽  
Fluid Phase ◽  
Fluorescein Isothiocyanate ◽  
Water Channels ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Apical Cell Membrane

Antidiuretic hormone (ADH) increases the osmotic water permeability (Pf) of the toad urinary bladder by insertion of water channels into the apical cell membrane. Transepithelial water flow (Jv) reduces Pf by inducing endocytosis of apical water channels despite continuous ADH stimulation. This phenomenon is termed flux inhibition. We wished to determine whether cytoplasmic dilution or transcellular Jv causes flux inhibition because both have been proposed previously as a primary regulatory mechanism for this process. Apical membrane endocytosis was quantified by monitoring the uptake of the fluid phase marker fluorescein isothiocyanate dextran (FITC-dextran). FITC-dextran fluorescence was monitored in Triton X-100 extracts of epithelial cells as the ratio of total tissue fluorescence compared with background fluorescence. The background was defined as cellular autofluorescence and nonspecific tissue staining due to the presence of small amounts of free fluorescein contaminating the FITC-dextran. FITC-dextran uptake measured under symmetric isotonic (220 mosmol/kgH2O) conditions in either the absence (1.0 +/- 0.4 SD; n = 14) or presence (1.3 +/- 0.3; n = 4) of ADH was not statistically different from that of background. In contrast, flux inhibition induced by a 180 mosmol/kgH2O apical-to-basolateral osmotic gradient increased FITC-dextran uptake to 3.4 +/- 1.3 (n = 7). FITC-dextran uptake was identical in bladders exposed to symmetric hypotonic (150 mosmol/kgH2O) solutions during ADH (3.6 +/- 0.9; n = 6) or adenosine 3',5'-cyclic monophosphate (3.1 +/- 0.4 fold; n = 3) stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Antidiuretic hormone modulates membrane phosphoproteins in toad urinary bladder and retrieved water channel containing apical membrane vesicles.

1991 ◽  
Vol 1 (9) ◽  
pp. 1114-1122
Author(s):  
H W Harris
Keyword(s):  
Membrane Proteins ◽  
Urinary Bladder ◽  
Membrane Protein ◽  
Antidiuretic Hormone ◽  
Water Permeability ◽  
Apical Membrane ◽  
Water Channel ◽  
Water Channels ◽  
Toad Urinary Bladder ◽  
Granular Cells

Antidiuretic hormone (ADH) dramatically increases the water permeability of toad urinary bladder by insertion of unique highly selective water channels into the apical membranes of granular cells. Before ADH stimulation, water channels are stored in high concentrations in the limiting membranes of large cytoplasmic vesicles called aggrephores. ADH stimulation causes aggrephore fusion with the granular cell apical membrane and increases water permeability. Transepithelial osmotic water flow causes a rapid attenuation of the ADH-elicited increase in water permeability through a process called flux inhibition. Flux inhibition is due to retrieval of ADH water channels by apical membrane endocytosis. When phosphoproteins of intact bladders are labeled with (32P)orthophosphate, the 32P content of 34-, 28-, and 17-kDa proteins is increased by ADH stimulation. When flux inhibition occurs, the 32P-labelling of a 15.5-kDa protein is reduced to approximately one half its original value (Konieczkowski M, Rudolph SA, J Pharmacol Exp Ther 1985;234:515). These observations have been confirmed, and these studies have been extended, by using a combination of subcellular fractionation and membrane protein chemistry techniques. All four of these phosphoproteins are present in membrane fractions of granular cells. Analysis of membrane proteins by a combination of Triton X-114 partitioning and an alkaline stripping technique reveals that the 28- and 17-kDa species are integral membrane proteins of unknown function. In contrast, the 32P-labeled 15.5-kDa protein is a peripheral membrane protein. It is attached to the cytoplasmic (outer) surface of highly water-permeable vesicles retrieved during flux inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Fate of antidiuretic hormone water channel proteins after retrieval from apical membrane

1993 ◽  
Vol 265 (3) ◽  
pp. C822-C833 ◽  
Author(s):  
M. L. Zeidel ◽  
T. G. Hammond ◽  
J. B. Wade ◽  
J. Tucker ◽  
H. W. Harris
Keyword(s):  
Membrane Proteins ◽  
Antidiuretic Hormone ◽  
Apical Membrane ◽  
Water Channel ◽  
Fluid Phase ◽  
Water Channels ◽  
Endocytic Pathway ◽  
Electron Microscopic ◽  
Channel Proteins ◽  
Fluorescence Measurements

In toad bladder granular cells, antidiuretic hormone (ADH) stimulates insertion of vesicles containing water channels (WCV), markedly increasing apical membrane osmotic water permeability (Pf). After withdrawal of ADH stimulation, WCV are removed from the apical membrane and fluid-phase markers endocytosed from the apical solution appear predominantly in endosomes at 10-15 min and multivesicular bodies at 30-60 min. Although the luminal contents of this endocytic pathway have been well characterized, the fate of membrane proteins, including functional ADH water channels in these vesicles remains unclear. Using electron microscopic, flow cytometric, and stopped-flow fluorescence measurements and characterization of labeled vesicle proteins, we examined the fate of membrane proteins contained within WCV. The protein complements of endosomes harvested after 10, 30, and 60 min of ADH withdrawal were similar. Selective covalent labeling of apical proteins during ADH stimulation followed by ADH reversal for 30 or 60 min showed that apical proteins colocalize with fluid-phase marker-labeled endosomes at all times, and most apically labeled protein bands present in the 10-min fraction were also present in the 30- and 60-min endosome fractions. Endosomes at 10 and 30 min but not at 60 min contained functional water channels revealed by high Pf and proton permeability, low activation energy of Pf, and sensitivity of Pf to mercurial reagents. We conclude that a portion of apically exposed membrane proteins, including candidate water channel proteins, travel together with fluid-phase markers from 10-min endosomes into later endosomal compartments. Functional water channels may be inactivated or some essential protein component selectively sorted away between 30 and 60 min after ADH withdrawal.

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