scholarly journals Aquaporin-1 in the peritoneal membrane: Implications for water transport across capillaries and peritoneal dialysis

2006 ◽  
Vol 1758 (8) ◽  
pp. 1078-1084 ◽  
Author(s):  
Olivier Devuyst ◽  
Jie Ni
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Peritoneal Membrane ◽  
Aquaporin 1

Monitoring of Long-Term Peritoneal Membrane Function

2001 ◽  
Vol 21 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Simon J. Davies
Keyword(s):  
Peritoneal Dialysis ◽  
Solute Transport ◽  
Water Transport ◽  
Drop Out ◽  
Published Data ◽  
Peritoneal Membrane ◽  
Membrane Function ◽  
Technique Survival ◽  
Ultrafiltration Failure

Objective Peritoneal membrane function influences dialysis prescription and clinical outcome and may change with time on treatment. Increasingly sophisticated tools, ranging from the peritoneal equilibration test (PET) to the standard permeability analysis (SPA) and personal dialysis capacity (PDC) test, are available to the clinician and clinical researcher. These tests allow assessment of a number of aspects of membrane function, including solute transport rates, ultrafiltration capacity, effective reabsorption, transcellular water transport, and permeability to macromolecules. In considering which tests are of greatest value in monitoring long-term membrane function, two criteria were set: those that result in clinically relevant interpatient differences in achieved ultrafiltration or solute clearances, and those that change with time in treatment. Study Selection Clinical validation studies of the PET, SPA, and PDC tests. Studies reporting membrane function using these methods in either long-term (5 years) peritoneal dialysis patients or longitudinal observations (> 2 years). Data Extraction Directly from published data. Additional, previously unpublished analysis of data from the Stoke PD Study. Results Solute transport is the most important parameter. In addition to predicting patient and technique survival at baseline, there is strong evidence that it can increase with time on treatment. Whereas patients with initially high solute transport drop out early from treatment, those with low transport remain longer on treatment, although, over 5 years, a proportion develop increasing transport rates. Ultrafiltration capacity, while being a composite measure of membrane function, is a useful guide for the clinician. Using the PET (2.27% glucose), a net ultrafiltration capacity of < 200 mL is associated with a 50% chance of achieving less than 1 L daily ultrafiltration at the expense of 1.8 hypertonic (3.86%) exchanges in anuric patients. Using a SPA (3.86% glucose), a net ultrafiltration capacity of < 400 mL indicates ultrafiltration failure. While there is circumstantial evidence that, with time on peritoneal dialysis, loss of transcellular water transport might contribute to ultrafiltration failure, none of the current tests is able to demonstrate this unequivocally. Of the other membrane parameters, evidence that interpatient differences are clinically relevant (permeability to macro-molecules), or that they change significantly with time on treatment (effective reabsorption), is lacking. Conclusion A strong case can be made for the regular assessment by clinicians of solute transport and ultrafiltration capacity, a task made simple to achieve using any of the three tools available.

In vivo inhibition of transcellular water channels (aquaporin-1) during acute peritoneal dialysis in rats

1996 ◽  
Vol 271 (6) ◽  
pp. H2254-H2262 ◽  
Author(s):  
O. Carlsson ◽  
S. Nielsen ◽  
el-R. Zakaria ◽  
B. Rippe
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Water Flow ◽  
Peritoneal Cavity ◽  
Critical Role ◽  
Water Channels ◽  
Capillary Endothelium ◽  
Tissue Fixation ◽  
Solute Permeability ◽  
Aquaporin 1

During peritoneal dialysis (PD), a major portion of the osmotically induced water transport to the peritoneum can be predicted to occur through endothelial water-selective channels. Aquaporin-1 (AQP-1) has recently been recognized as the molecular correlate to such channels. Aquaporins can be inhibited by mercurials. In the present study, HgCl2 was applied locally to the peritoneal cavity in rats after short-term tissue fixation, used to protect the tissues from HgCl2 damage. Dianeal (3.86%) was employed as dialysis fluid, 125I-albumin as an intraperitoneal volume marker, and 51Cr-EDTA (constantly infused intravenously) to assess peritoneal small-solute permeability characteristics. Immunocytochemistry and immunoelectron microscopy revealed abundant AQP-1 labeling in capillary endothelium in peritoneal tissues, representing sites for HgCl2 inhibition of water transport. HgCl2 treatment reduced water flow and inhibited the sieving of Na+ without causing any untoward changes in microvascular permeability, compared with that of fixed control rats, in which the peritoneal cavity was exposed to tissue fixation alone. In fixed control rats, the mean intraperitoneal volume (IPV) increased from 20.5 +/- 0.15 to 25.0 +/- 0.52 ml in 60 min, whereas in the HgCl2-treated rats, the increment was only from 20.7 +/- 0.23 to 23.5 +/- 0.4 ml. In fixed control rats, the dialysate Na+ fell from 135.3 +/- 0.97 to 131.3 +/- 1.72 mM, whereas in the HgCl2-treated rats the dialysate Na+ concentration remained unchanged between 0 and 40 min, further supporting that water channels had been blocked. Computer simulations of peritoneal transport were compatible with a 66% inhibition of water flow through aquaporins. The observed HgCl2 inhibition of transcellular water channels strongly indicates a critical role of aquaporins in PD and provides evidence that water channels are crucial in transendothelial water transport when driven by crystalloid osmosis.

scholarly journals Aquaporin-1 Facilitates Transmesothelial Water Permeability: In Vitro and Ex Vivo Evidence and Possible Implications in Peritoneal Dialysis

2021 ◽  
Vol 22 (22) ◽  
pp. 12535
Author(s):  
Francesca Piccapane ◽  
Andrea Gerbino ◽  
Monica Carmosino ◽  
Serena Milano ◽  
Arduino Arduini ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Peritoneal Dialysis ◽  
Tight Junctions ◽  
Water Transport ◽  
Water Flux ◽  
Water Channel ◽  
Bathing Solution ◽  
Ussing Chambers ◽  
Aquaporin 1 ◽  
Osmotic Water

We previously showed that mesothelial cells in human peritoneum express the water channel aquaporin 1 (AQP1) at the plasma membrane, suggesting that, although in a non-physiological context, it may facilitate osmotic water exchange during peritoneal dialysis (PD). According to the three-pore model that predicts the transport of water during PD, the endothelium of peritoneal capillaries is the major limiting barrier to water transport across peritoneum, assuming the functional role of the mesothelium, as a semipermeable barrier, to be negligible. We hypothesized that an intact mesothelial layer is poorly permeable to water unless AQP1 is expressed at the plasma membrane. To demonstrate that, we characterized an immortalized cell line of human mesothelium (HMC) and measured the osmotically-driven transmesothelial water flux in the absence or in the presence of AQP1. The presence of tight junctions between HMC was investigated by immunofluorescence. Bioelectrical parameters of HMC monolayers were studied by Ussing Chambers and transepithelial water transport was investigated by an electrophysiological approach based on measurements of TEA+ dilution in the apical bathing solution, through TEA+-sensitive microelectrodes. HMCs express Zo-1 and occludin at the tight junctions and a transepithelial vectorial Na+ transport. Real-time transmesothelial water flux, in response to an increase of osmolarity in the apical solution, indicated that, in the presence of AQP1, the rate of TEA+ dilution was up to four-fold higher than in its absence. Of note, we confirmed our data in isolated mouse mesentery patches, where we measured an AQP1-dependent transmesothelial osmotic water transport. These results suggest that the mesothelium may represent an additional selective barrier regulating water transport in PD through functional expression of the water channel AQP1.

Expression of aquaporin-1 in a long-term peritoneal dialysis patient with impaired transcellular water transport

1999 ◽  
Vol 33 (2) ◽  
pp. 383-388 ◽  
Author(s):  
Eric Goffin ◽  
Sophie Combet ◽  
François Jamar ◽  
Jean-Pierre Cosyns ◽  
Olivier Devuyst
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Dialysis Patient ◽  
Peritoneal Dialysis Patient ◽  
Aquaporin 1

Quantification of osmotic water transport in vivo using fluorescent albumin

2014 ◽  
Vol 307 (8) ◽  
pp. F981-F989 ◽  
Author(s):  
Johann Morelle ◽  
Amadou Sow ◽  
Didier Vertommen ◽  
François Jamar ◽  
Bengt Rippe ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Molecular Mechanisms ◽  
Water Channel ◽  
Transgenic Animals ◽  
Peritoneal Membrane ◽  
Intraperitoneal Pressure ◽  
Alexa Fluor ◽  
Osmotic Water

Osmotic water transport across the peritoneal membrane is applied during peritoneal dialysis to remove the excess water accumulated in patients with end-stage renal disease. The discovery of aquaporin water channels and the generation of transgenic animals have stressed the need for novel and accurate methods to unravel molecular mechanisms of water permeability in vivo. Here, we describe the use of fluorescently labeled albumin as a reliable indicator of osmotic water transport across the peritoneal membrane in a well-established mouse model of peritoneal dialysis. After detailed evaluation of intraperitoneal tracer mass kinetics, the technique was validated against direct volumetry, considered as the gold standard. The pH-insensitive dye Alexa Fluor 555-albumin was applied to quantify osmotic water transport across the mouse peritoneal membrane resulting from modulating dialysate osmolality and genetic silencing of the water channel aquaporin-1 (AQP1). Quantification of osmotic water transport using Alexa Fluor 555-albumin closely correlated with direct volumetry and with estimations based on radioiodinated (125I) serum albumin (RISA). The low intraperitoneal pressure probably accounts for the negligible disappearance of the tracer from the peritoneal cavity in this model. Taken together, these data demonstrate the appropriateness of pH-insensitive Alexa Fluor 555-albumin as a practical and reliable intraperitoneal volume tracer to quantify osmotic water transport in vivo.

Aquaporin-1: New Developments and Perspectives for Peritoneal Dialysis

2010 ◽  
Vol 30 (2) ◽  
pp. 135-141 ◽  
Author(s):  
Olivier Devuyst ◽  
Andrea J. Yool
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Water Channel ◽  
Cell Types ◽  
Convective Transport ◽  
Osmotic Gradient ◽  
Pharmacological Agents ◽  
Solute Permeability ◽  
Chemical Screening ◽  
Aquaporin 1

Peritoneal dialysis involves diffusive and convective transport and osmosis through the highly vascularized peritoneal membrane. Several lines of evidence have demonstrated that the water channel aquaporin-1 (AQP1) corresponds to the ultrasmall pore predicted by the model of peritoneal transport. Proof-of-principle studies have shown that upregulation of the expression of AQP1 in peritoneal capillaries results in increased water permeability and ultrafiltration, without affecting the osmotic gradient or small solute permeability. Conversely, studies in Aqp1 mice have shown that haplo-insufficiency for AQP1 results in significant attenuation of water transport. Recent studies have demonstrated that AQP1 is involved in the migration of different cell types, including endothelial cells. In parallel, chemical screening has identified lead compounds that could act as antagonists or agonists of AQPs, with description of putative binding sites and potential mechanisms of gating the water channel. By modulating water transport, these pharmacological agents could have clinically relevant effects in targeting specific tissues or disease states.

scholarly journals Mechanisms of Crystalloid versus Colloid Osmosis across the Peritoneal Membrane

2018 ◽  
Vol 29 (7) ◽  
pp. 1875-1886 ◽  
Author(s):  
Johann Morelle ◽  
Amadou Sow ◽  
Charles-André Fustin ◽  
Catherine Fillée ◽  
Elvia Garcia-Lopez ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Water Flow ◽  
Molecular Mechanisms ◽  
Experimental Models ◽  
Peritoneal Membrane ◽  
Aquaporin 1 ◽  
Dialysis Solution ◽  
Osmotic Water ◽  
Osmotic Agents

Background Osmosis drives transcapillary ultrafiltration and water removal in patients treated with peritoneal dialysis. Crystalloid osmosis, typically induced by glucose, relies on dialysate tonicity and occurs through endothelial aquaporin-1 water channels and interendothelial clefts. In contrast, the mechanisms mediating water flow driven by colloidal agents, such as icodextrin, and combinations of osmotic agents have not been evaluated.Methods We used experimental models of peritoneal dialysis in mouse and biophysical studies combined with mathematical modeling to evaluate the mechanisms of colloid versus crystalloid osmosis across the peritoneal membrane and to investigate the pathways mediating water flow generated by the glucose polymer icodextrin.ResultsIn silico modeling and in vivo studies showed that deletion of aquaporin-1 did not influence osmotic water transport induced by icodextrin but did affect that induced by crystalloid agents. Water flow induced by icodextrin was dependent upon the presence of large, colloidal fractions, with a reflection coefficient close to unity, a low diffusion capacity, and a minimal effect on dialysate osmolality. Combining crystalloid and colloid osmotic agents in the same dialysis solution strikingly enhanced water and sodium transport across the peritoneal membrane, improving ultrafiltration efficiency over that obtained with either type of agent alone.Conclusions These data cast light on the molecular mechanisms involved in colloid versus crystalloid osmosis and characterize novel osmotic agents. Dialysis solutions combining crystalloid and colloid particles may help restore fluid balance in patients treated with peritoneal dialysis.

Sodium Sieving in Children

2005 ◽  
Vol 25 (3_suppl) ◽  
pp. 141-142 ◽  
Author(s):  
Esther Rusthoven ◽  
Raymond T. Krediet ◽  
Hans L. Willems ◽  
Leo A. Monnens ◽  
Cornelis H. Schröder
Keyword(s):  
Peritoneal Dialysis ◽  
Water Transport ◽  
Minor Role ◽  
Peritoneal Membrane ◽  
A Minor ◽  
Sodium Sieving

Sodium sieving is a consequence of dissociation between the amount of water and sodium transported over the peritoneal membrane. This dissociation occurs in the presence of aquaporin-mediated water transport. Sieving of sodium can be used as a rough measure for aquaporin-mediated water transport. Icodextrin contains glucose polymers, inducing ultrafiltration by colloid osmosis. Therefore, aquaporins play a minor role in ultrafiltration, which is confirmed by the absence of sodium sieving. Icodextrin is very suitable for the daytime dwell in children on a nightly intermittent peritoneal dialysis regimen. Ultrafiltration obtained with icodextrin is similar to ultrafiltration obtained with 3.86% glucose after a 12-hour dwell. When using icodextrin in children, it is also confirmed by the absence of sodium sieving that the aquaporins play a minor role in ultrafiltration.

Sign in / Sign up

Export Citation Format

Share Document