Urea Permeability Research Articles

Structural insights into the mechanisms of urea permeation and distinct inhibition modes of urea transporters

Urea’s transmembrane transport through urea transporters (UT) is a fundamental physiological behavior for life activities. Here, we present 11 cryo-EM structures of four UT members in resting states, urea transport states, or inactive states bound with synthetic competitive, uncompetitive or noncompetitive inhibitor. Our results indicate that the binding of urea via a conserved urea recognition motif (URM) and the urea transport via H-bond transfer along the QPb-T5b-T5a-QPa motif among different UT members. Moreover, distinct binding modes of the competitive inhibitors 25a and ATB3, the uncompetitive inhibitor CF11 and the noncompetitive inhibitor HQA2 provide different mechanisms for blocking urea transport and achieved selectivity through L-P pocket, UCBP region and SCG pocket, respectively. In summary, our study not only allows structural understanding of urea transport via UTs but also afforded a structural landscape of hUT-A2 inhibition by competitive, uncompetitive and noncompetitive inhibitors, which may facilitate developing selective human UT-A inhibitors as a new class of salt-sparing diuretics.

Cell Volume Regulation of Endothelial Cells Is Impaired in Keratoconus Cornea

In this work the permeability to water and urea of plasma membranes of endothelial cells of normal corneas and corneas with keratoconus was investigated. The endothelial cells were obtained from surgery material. Measurements of osmotic aqueous permeability (Pf) of endothelial cells in normal and in keratoconus did not reveal significant differences of this parameter in the two studied groups. The control cells and the cells from keratoconus cornea have similar osmotic water permeability (control cells, Pf = 0.53 ± 0.045 cm/s; keratoconus cells, Pf = 0.63 ± 0.041 cm/s; n = 25; p ≥ 0.05). Neither coefficient of urea permeability differed significantly in these groups (control, Pu = 0.049 ± 0.003 cm/s; keratoconus, Pu = 0.056 ± 0.003 cm/s; n = 25; p ≥ 0.05). Analysis of cell volume dynamics based on exponential approximation showed a more pronounced decrease of the cell volume of endothelial cells from keratoconus cornea in hypertonic medium in comparison with the cells from normal cornea. The increase of cell volume caused by isotonic entering of urea into the cells in hypertonic medium also was more pronounced in these cells in comparison with the normal ones. We conclude that there are significant changes in cell volume regulating mechanism in keratoconus cornea endothelial cells.

Optimization of Chitosan-Carboxymethyl Chitosan Membrane Modification with PVA to Increase Creatinine and Urea Permeation Efficiency

Polyvinyl alcohol (PVA) modified chitosan-carboxymethyl chitosan (CMC) membrane has been successfully fabricated and used as a dialysis membrane. This research aims to examine the manufacturing process, characterization, and dialysis performance of CMC and PVA-modified chitosan membranes. The membrane used the phase inversion method in acetic acid solvent with 5 CS:CMC: PVA dope compositions. Based on FTIR data, the modification process did not produce new spectra. Furthermore, the interaction produces a membrane with higher physical characteristics in terms of porosity, swelling, water uptake, hydrophilicity, and pH resistance values, which increase by 1.5–115%. Meanwhile, chitosan modification makes the membrane structure different from the original, requiring a longer degradation time. The modification also increased the permeation ability of urea by 17–65% and creatinine permeation by 20–62%. Membranes have the ability to be used more than once.

Permeation of urea and water through sulfonated poly(styrene‐isobutylene‐styrene) membranes with counterion substitution

AbstractThis study describes the influence of counterion substitution on the transport of urea and water through sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) membranes. SIBS was sulfonated to 66.4% to allow for enough ionic domains to transport urea and water through the membrane. Counterions, including alkyl‐substituted ammonium ions, influenced the ionic domains creating a selective barrier that hindered the transport of urea and water through SIBS. Permeability measurements demonstrated that counterion substitution significantly affected the transport of urea. Membranes with higher charge counterions exhibited a more pronounced reduction in permeability due to the formation of crosslinks and increased restriction on molecular diffusion. Membranes substituted with ammonium salts showed reduced permeability due to the alkyl chains' hydrophobic nature, which created a physical barrier against the passage of urea molecules. Pure water flux tests indicated that counterion substitution also reduced the water flux of the membranes. Membranes with +1 counterions showed a small reduction in the water flux, while membranes with higher charge counterions and alkyl chain substitutions exhibited larger reductions, highlighting the influence of crosslinking and hydrophobicity on water transport.

Urea and water are transported through different pathways in the red blood cell membrane.

Several studies of the urea transporter UT-B expressed in Xenopus oocytes and in genetically modified red blood cells (RBC) have concluded that UT-B also transports water. In the present study, we use unmodified RBC to test that conclusion. We find that the permeability of urea, Pu (cm/s), has a 10-fold donor variation, while the diffusional water permeability, Pd (cm/s), remains unchanged. Additionally, we observe that phloretin inhibits Pu but not Pd, and that the time course of maximum p-chloromercuribenzosulfonate inhibition of Pu and Pd differs-Pu inhibition takes <2 min, whereas Pd inhibition requires ≥1 h of incubation. The findings in the present study are in line with a previous comparative study using unmodified RBC from four animals and a solvent drag study using human RBC, and they lead us to reject the conclusion that the UT-B transporter represents a common pathway for both solutes.

Phosphatases Decrease Water and Urea Permeability in Rat Inner Medullary Collecting Ducts.

We previously showed that the phosphatases PP1/PP2A and PP2B dephosphorylate the water channel, AQP2, suggesting their role in water reabsorption. In this study, we investigated whether protein phosphatase 2A (PP2A) and protein phosphatase 2B (PP2B or calcineurin), which are present in the inner medullary collecting duct (IMCD), are regulators of urea and water permeability. Inhibition of calcineurin by tacrolimus increased both basal and vasopressin-stimulated osmotic water permeability in perfused rat IMCDs. However, tacrolimus did not affect osmotic water permeability in the presence of aldosterone. Inhibition of PP2A by calyculin increased both basal and vasopressin-stimulated osmotic water permeability, and aldosterone reversed the increase by calyculin. Previous studies showed that adrenomedullin (ADM) activates PP2A and decreases osmotic water permeability. Inhibition of PP2A by calyculin prevented the ADM-induced decrease in water reabsorption. ADM reduced the phosphorylation of AQP2 at serine 269 (pSer269 AQP2). Urea is linked to water reabsorption by building up hyperosmolality in the inner medullary interstitium. Calyculin increased urea permeability and phosphorylated UT-A1. Our results indicate that phosphatases regulate water reabsorption. Aldosterone and adrenomedullin decrease urea or osmotic water permeability by acting through calcineurin and PP2A, respectively. PP2A may regulate water reabsorption by dephosphorylating pSer269, AQP2, and UT-A1.

The Effect of Temperature, Sulfonation, and PEG Addition on Physicochemical Characteristics of PVDF Membranes and Its Application on Hemodialysis Membrane

Polyvinylidene fluoride (PVDF) membrane and its derivative have been investigated the permeation ability for creatinine and urea. The membrane was made by an inversion precipitation system in N,N-dimethyl acetamide (DMAc) and water as non-solvents. In this study, the modification of PVDF membrane permeability with PEG additives, CBT variations, and sulfonation was successfully carried out. The membrane solidification process was carried out on three variations of the coagulation bath temperature (CBT): 30, 45, and 60 °C. Eight types of membranes were characterized by using FT-IR and TGA/DSC, followed by the analysis of their porosity, hydrophilicity, water uptake, swelling degree, tensile strength, and permeability of creatinine and urea. The FT-IR spectra indicate that PVDF modification has been successfully carried out. The porosity, hydrophilicity, water uptake, and swelling degree values increase with the modification of functional groups. Furthermore, improvements in creatinine and urea permeability and clearances are achieved by increasing CBT and sulfonation in the PVDF/PEG membrane. The presence of sulfonate groups improves the membrane permeability through the interaction of intermolecular hydrogen with water and dialysate compounds. The existence of PEG as a porogen enhanced membrane porosity. Creatinine and urea clearance values increase from 0.29–0.58 and 6.38–20.63 mg/dL, respectively.

Molecular dynamics simulation of human urea transporter B

ABSTRACT We applied a new large two membrane model of human urea transporter B (UT-B) with urea concentration gradient between intracellular and extracellular solution to explore the structure and dynamics of urea permeation. The first solved human UT-B X-ray crystal structure (PDB 6QD5) was studied using atomistic force field based large scale molecular dynamics (MD) simulations. The urea binding sites in UT-B were identified by the combination of first principles molecular dynamics docking and hybrid steered molecular dynamics (hSMD). In the simulations, urea molecules bound to the two binding sites although urea molecules did not go through the channels. The potential of mean force (PMF) of urea along the channel was calculated by hSMD to investigate the selectivity of the urea permeation across the channel pore. The simulations provide an opportunity to explore the binding sites spontaneously to help understand the urea permeation gating and transportation mechanism. A clearer analysis of the selectivity filter is shown in more detail. We also furthered the research about small organic molecules in the specific environment, such as channels in this work.

INFLUENCE OF OXYGENATOR EXTRACORPORAL CIRCUIT TREATMENT WITH ADAPTATION COMPOSITION (AdC) ON MORPHOLOGICAL CHANGES OF ERYTHROCYTES.

Summary. The study highlights a method of treatment extracorporeal circuit with «adaptation composition» (AdC) for the reduction of negative impact on state of erythrocytes.&#x0D; Materials and methods. A total of 90 patients were enrolled, they were divided into two groups. The group 1 (45 patients, 39/6 male/female) included patients who underwent surgical procedures without treatment of an extracorporeal circuit with AdC. The group 2 (45 patients, 39/6 male/female) included patients who underwent surgery with the treatment of an extracorporeal circuit with AdC. According to the study protocol, patient blood was sampling for complete blood cell count (CBC) and erythrocyte morphology at 4 stages of surgery: before surgery, at 10 min. CPB-time, at 60 min. CPB-time and after separation from CPB.&#x0D; Results. The albumin of AdC creates a protective nanolayer on the surface of the oxygenator membrane and tubes. There were no statistically significant differences of parameters in the groups before CPB. Level of Ht 2 (group 2) at 60 min CPB-time and after CPB, were lower than Ht 1 (group 1) (p=0.021 and p=0.035 correspondingly) because MCV1 was higher (р=0.025 and p&lt;0.0001 correspondingly). The increase MCHC in groups at 10 min. CPB-time relatives with the decrease in MCV at 10 min CPB-time. At 60 min, there are changes of RDWa2 76.05 ± 5.46 and RDWa1 72.35 ± 7.26, p&lt;0.000. After CPB higher content of reticulocytes (р &lt;0.0001), echinocytes (р &lt;0.0001) and spherocytes (р &lt;0.0001) is observed in group 1. The lowering of mechanical resistance (р = 0.04) and increasing membrane permeability for urea were in group 1. After CPB the best aсid hemolysis resistance was in group 2 (р = 0.05), erythrocytes were more resistant to hypoosmotic factor (р = 0.01) in group 2.&#x0D; Conclusion. The treatment of oxygenator with AdC reduces the negative influence СРВ on state of RBC. Membranes of erythrocytes were more resistant to traumatic factors in the group with AdC.

Aldosterone Decreases Vasopressin-Stimulated Water Reabsorption in Rat Inner Medullary Collecting Ducts.

Aldosterone indirectly regulates water reabsorption in the distal tubule by regulating sodium reabsorption. However, the direct effect of aldosterone on vasopressin-regulated water and urea permeability in the rat inner medullary collecting duct (IMCD) has not been tested. We investigated whether aldosterone regulates osmotic water permeability in isolated perfused rat IMCDs. Adding aldosterone (500 nM) to the bath significantly decreased osmotic water permeability in the presence of vasopressin (50 pM) in both male and female rat IMCDs. Aldosterone significantly decreased aquaporin-2 (AQP2) phosphorylation at S256 but did not change it at S261. Previous studies show that aldosterone can act both genomically and non-genomically. We tested the mechanism by which aldosterone attenuates osmotic water permeability. Blockade of gene transcription with actinomycin D did not reverse aldosterone-attenuated osmotic water permeability. In addition to AQP2, the urea transporter UT-A1 contributes to vasopressin-regulated urine concentrating ability. We tested aldosterone-regulated urea permeability in vasopressin-treated IMCDs. Blockade of gene transcription did not reverse aldosterone-attenuated urea permeability. In conclusion, aldosterone directly regulates water reabsorption through a non-genomic mechanism. Aldosterone-attenuated water reabsorption may be related to decreased trafficking of AQP2 to the plasma membrane. There may be a sex difference apparent in the inhibitory effect of aldosterone on water reabsorption in the inner medullary collecting duct. This study is the first to show a direct effect of aldosterone to inhibit vasopressin-stimulated osmotic water permeability and urea permeability in perfused rat IMCDs.

Rapid effects of aldosterone and phosphatase inhibition on water and urea permeabilities

Aldosterone promotes renal sodium uptake, thereby increasing water reabsorption. But our previous data showed that aldosterone decreases UT‐A1 urea transporter expression, suggesting aldosterone could inhibit water reabsorption. In this study, we investigated the rapid effect of aldosterone on vasopressin‐stimulated osmotic water permeability in rat inner medullary collecting ducts (IMCDs). In IMCDs from male Sprague Dawley rats weighing 50–75g, we saw that aldosterone significantly decreased osmotic water permeability from 152 ± 21 to 122 ± 17 μm/s (45 min, n=4, p&lt;0.01). Given the rapid nature of the response, we further investigated whether the effect of aldosterone might be through phosphatase‐mediated modulation of transporter phosphorylation. Inhibition of PP1/PP2a phosphatases by calyculin increased basal osmotic water permeability from 58 ± 8 to 92 ± 14 μm/s (n=4, p&lt;0.01). In the presence of vasopressin, stimulation by calyculin remained significant in both male and female rats 77 ± 10 to 119 ± 15 μm/s (30 min, n=6, p&lt;0.01). Addition of aldosterone to the bath in the presence of calyculin reversed the increase in osmotic water permeability from 119 ± 15 to 89 ± 10 μm/s (45 min, p&lt;0.01). Inhibition of pp2B with tacrolimus also stimulated water permeability (88 ± 13 to 108 ± 19 μm/s), which was reversed by addition of aldosterone (81 ± 10 μm/s). Urea permeability was also increased by both calyculin (25 ± 7 × 10−5 to 32 ± 7 × 10−5 cm/s; n=3, p&lt;0.05) and tacrolimus (15 ± 1 × 10−5 to 18 ± 1 × 10− 5 cm/s; n=4, p&lt;0.05). Aldosterone decreased pser256‐ and increased pser261‐AQP2. Inhibition of PP2B by tacrolimus increased pser256‐ and decreased pser261‐AQP2. Calyculin increases pser256‐AQP2 and this was reversed by aldosterone. Treatment of inner medullary tissue with 50 nM calyculin or 62 nM tacrolimus resulted in significantly increased UT‐A1 phosphorylation. We conclude that aldosterone is able to rapidly inhibit water and urea reabsorption, possibly by altering phosphatase activity and changing the phosphorylation states of AQP2 and UT‐A1.Support or Funding InformationAHA 18CDA34060053NIH/NIDDKRO1‐DK41707

Hybrid flat sheet cellulose acetate/silicon dioxide ultrafiltration membranes for uremic blood purification

Monophasic hybrid cellulose acetate/silica (CASiO2) integrally skinned membranes with tailored hemocompatible surfaces and permeation properties that assure the kidney metabolic functions of preferential permeation of urea and the retention of albumin were synthesized by an innovative method which combines the phase inversion and sol–gel techniques. The morphological and topographical characterization of the hybrid CASiO2 membranes with silica contents between 5 and 18 wt% was performed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Static contact angles were measured through the sessile drop method and permeation experiments were performed to determine the hydraulic permeability and rejection coefficients to reference solutes pertaining to the metabolic functions of the kidney. SEM confirmed asymmetric membrane cross-section structures and AFM showed that the introduction of silica reduced the submicron surface roughness at least 3 times when compared to the pure CA membrane, reaching a roughness mean value below 2.5 nm. Contact angles revealed that the wettability increased for membranes containing 11 and 18 wt%. Permeation studies show that the integration of silica into CA membranes increased the hydraulic permeability of the hybrid CASiO2 membranes by a factor of ~ 2 and that all hybrid membranes fully permeated urea and completely rejected albumin. In terms of hemocompatibility, all CASiO2 membranes were non-hemolytic, low thrombogenic and did not promote the highest stages of platelet activation.

Water channel pore size determines exclusion properties but not solute selectivity

Aquaporins (AQPs) are a ubiquitous family of transmembrane water channel proteins. A subgroup of AQP water channels also facilitates transmembrane diffusion of small, polar solutes. A constriction within the pore, the aromatic/arginine (ar/R) selectivity filter, is thought to control solute permeability: previous studies on single representative water channel proteins suggest narrow channels conduct water, whilst wider channels permit passage of solutes. To assess this model of selectivity, we used mutagenesis, permeability measurements and in silico comparisons of water-specific as well as glycerol-permeable human AQPs. Our studies show that single amino acid substitutions in the selectivity filters of AQP1, AQP4 and AQP3 differentially affect glycerol and urea permeability in an AQP-specific manner. Comparison between in silico-calculated channel cross-sectional areas and in vitro permeability measurements suggests that selectivity filter cross-sectional area predicts urea but not glycerol permeability. Our data show that substrate discrimination in water channels depends on a complex interplay between the solute, pore size, and polarity, and that using single water channel proteins as representative models has led to an underestimation of this complexity.

The vertebrate Aqp14 water channel is a neuropeptide-regulated polytransporter

Water channels (aquaporins) were originally discovered in mammals with fourteen subfamilies now identified (AQP0-13). Here we show that a functional Aqp14 subfamily phylogenetically related to AQP4-type channels exists in all vertebrate lineages except hagfishes and eutherian mammals. In contrast to the water-selective classical aquaporins, which have four aromatic-arginine constriction residues, Aqp14 proteins present five non-aromatic constriction residues and facilitate the permeation of water, urea, ammonia, H2O2 and glycerol. Immunocytochemical assays suggest that Aqp14 channels play important osmoregulatory roles in piscine seawater adaptation. Our data indicate that Aqp14 intracellular trafficking is tightly regulated by the vasotocinergic/isotocinergic neuropeptide and receptor systems, whereby protein kinase C and A transduction pathways phosphorylate highly conserved C-terminal residues to control channel plasma membrane insertion. The neuropeptide regulation of Aqp14 channels thus predates the vasotocin/vasopressin regulation of AQP2-5-6 orthologs observed in tetrapods. These findings demonstrate that vertebrate Aqp14 channels represent an ancient subfamily of neuropeptide-regulated polytransporters.

Grafting of Heparin on Blend Membrane of Citric Acid Crosslinked Chitosan/Polyethylene Glycol-Poly Vinyl Alcohol (PVA-PEG)

Heparin, an active sulfate group material, grafted onto blend membrane citric acid cross-linked chitosan/poly (vinyl alcohol)-poly(ethylene glycol) (PVA-PEG) to improve the membrane properties. The physical tests shown that grafting reaction of citric acid crosslinked chitosan increased the mechanical strength and membrane swelling. The permeability test results, it was found that the grafted chitosan membrane was improved permeability of both urea and creatinine as compared to chitosan pure and chitosan crosslinked membrane. The negative charge of the sulphonate group of heparin increased the number of the active side of the carrier in the membrane, which then correlated to the membrane’s permeability process.

Skin Permeation of Urea Under Finite Dose Condition

In a previous study investigating the relationships between solute physicochemical properties and solvent effects on skin permeation of solutes under finite dose conditions, urea was found to have the highest percent dose absorbed among the model solutes studied. The objective of this study is to probe the mechanism of the observed high skin permeation of urea at finite dose, in contrast to its permeability coefficient obtained under infinite dose condition. Skin permeation experiments were performed with Franz diffusion cells and human epidermal membrane. Dose-dependence and penetration enhancing effects of urea permeation were investigated. Tape stripping was performed. A small hydrophilic solute ethylene glycol with molecular weight similar to urea was studied for comparison. The results suggest that urea did not have penetration enhancing effect to enhance solute permeation across skin under the finite dose conditions. Tape stripping data are consistent with skin permeation mechanism of solute deposition and diffusion. The skin permeation behavior of urea could be attributed to its small molecular size. This suggests that, under the finite dose conditions examined in this study, solutes with molecular sizes similar to or less than urea and ethylene glycol could lead to high percent of skin absorption despite their hydrophilicities.

Transepithelial Na and Urea Transport Pathways in Rat Inner Medullary Thin Limbs of Henle's Loop

Identification of key transport pathways for Na and urea in thin limbs of Henle's loops will further explain how solute recycling and countercurrent mechanisms are integrated to produce the corticomedullary osmotic gradient. We studied transepithelial Na and urea fluxes by in vivo microperfusion of papillary descending and ascending thin limbs (DTLs and ATLs, respectively) and by in vitro microperfusion of isolated DTLs and ATLs from the upper and lower 50% of the inner medulla (IM). In vitro studies have shown that transepithelial water permeability (Pf) is high in DTLupper and low in DTLlower, ATLupper and ATLlower. In vivo microperfusion studies confirmed the low Pf in papillary DTLs and ATLs. Mean transepithelial Na and urea permeabilities (PNa, Purea) with in vitro lumen perfusion rates of ~30 nl/min in DTLupper were ~60 E‐5 cm/sec and in DTLlower and ATL were ~350 to 450 E‐5 cm/sec; Na and urea fluxes in DTLlower are directly proportional to lumen perfusion rates between 5 to 30 nl/min. In vivo microperfusion studies confirmed the high PNa and Purea in papillary DTLs and ATLs. With in vitro microperfusion, Purea in DTLupper and DTLlower was not inhibited by peritubular phloretin (0.25 mM) indicating that urea fluxes occur independently of known facilitated urea transporters such as UT‐A1, UT‐A2 or UT‐A3. Furthermore, Purea in DTLlower was not inhibited by ouabain (10 mM) or by a lumen‐to‐bath Na concentration gradient (143 mM/lumen and 0 mM/bath) indicating the absence of Na‐dependent urea transport. On the other hand, Purea in DTLupper and DTLlower were almost completely inhibited by peritubular lanthanum (5 mM), with Purea recovering in both segments following 20 min lanthanum washout. Lanthanum (5 mM) also completely inhibited PNa in DTLlower; however, PNa remained completely inhibited following 20 min washout. Activation energy for transepithelial Na and urea transport determined by in vitro microperfusion during 37°‐ to −16° C temperature transitions was found to be low in DTLupper (~1–2 kJ/mol) compared to DTLlower and ATL (~13 kJ/mol). Urea transport in DTLupper and Na and urea transport in DTLlower and ATL likely occur in large part, by way of a plasma membrane or paracellular channel‐like pathway. The distinctive transport characteristics suggest that there are different mechanisms involved with PNa and Purea in upper and lower DTLs, respectively.Support or Funding InformationNIDDK DK083338 (TP)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Vapor-gap membranes for highly selective osmotically driven desalination

In this study, we demonstrate nanostructured osmosis membranes that employ vapor-phase water transport to simultaneously achieve high rejection of solutes and a high permeability. The membranes consist of a hydrophobic, thermally conductive silica nanoparticle (SiNP) layer with tunable thickness supported by a hydrophilic track-etched membrane. The membrane permeability for water vapor is 1–2 orders of magnitude higher than hydrophobic microporous membranes used for osmotic distillation. This permeability is only mildly lower (~ 3 times) than the equivalent water permeability of typical forward osmosis (FO) membranes. We also demonstrate the high selectivity of the SiNP membrane via urea permeation tests, where this membrane exhibits a 2–3 orders of magnitude lower urea permeability coefficient than a thin-film composite (TFC) FO membrane. Further measurements and theoretical analysis using the dusty-gas model suggest that membranes with a smaller SiNP layer thickness are capable of having comparable water fluxes to TFC FO membranes while maintaining higher selectivity. Our work demonstrates that thin, hydrophobic nanostructured membranes composed of thermally conductive materials have a great potential to significantly extend the applications of osmosis-driven processes to treat challenging water sources.

Desmopressin Causes Different Effects on Water and Urea Permeability of Principal Cells in OMCD and IMCD

Desmopressin Causes Different Effects on Water and Urea Permeability of Principal Cells in OMCD and IMCD

Polar/nonpolar gas transfer through PEO-based copolymers membranes

ABSTRACTTwo PEG-based copolymers containing two different chain extenders, as hard segments, were synthesized by 4,4′-methylenediphenyl diisocyanate (MDI). The chain extenders were 1,4-butane diol (BDO) and 1,2-ethane diamine (EDA). The application of the polyurethane (PU) and poly(urethane-urea)s (PUU)s synthesized polymers, which were characterized by Fourier transform infrared spectrometer (FTIR), differential scanning calorimetry (DSC) and atomic Force Microscopy (AFM), in the gas permeability was investigated. The obtained results indicated that by replacing the urea linkage in the polymers, the microphase separation of hard and soft segments increased. The synthesized PEG-based copolymers were semi-crystalline at room temperature. According to the DSC results, the crystallinity of the synthesized polyurethanes decreased as temperature increased. In addition, a reduction in mean surface roughness could be seen based AMF information. The gas (carbon dioxide and methane) separation properties of the polymers revealed that by replacing the urea linkage, the diffusivity, permeability and selectivity of the gases increased slightly.The solubility and diffusivity of gases indicated he solubility domination of gas transport in these membranes. However, the sorption coefficient (S) of a particular gas was surprisingly constant for the two synthesized polymers. The CO2 permeability increased with increasing feed pressure, while CH4 permeability remained almost constant at both temperatures of 25°C and 35°C. The increase in temperature led to an increase in the permeability of the gases and a decrease in the gas selectivity for the both synthesized polyurethanes.