Monovalent Ion Transport Research Articles

In situ generation of (sub) nanometer pores in MoS2 membranes for ion-selective transport

Ion selective membranes are fundamental components of biological, energy, and computing systems. The fabrication of solid-state ultrathin membranes that can separate ions of similar size and the same charge with both high selectivity and permeance remains a challenge, however. Here, we present a method, utilizing the application of a remote electric field, to fabricate a high-density of (sub)nm pores in situ. This method takes advantage of the grain boundaries in few-layer polycrystalline MoS2 to enable the synthesis of nanoporous membranes with average pore size tunable from <1 to ~4 nm in diameter (with in situ pore expansion resolution of ~0.2 nm2 s−1). These membranes demonstrate selective transport of monovalent ions (K+, Na+ and Li+) as well as divalent ions (Mg2+ and Ca2+), outperforming existing two-dimensional material nanoporous membranes that display similar total permeance. We investigate the mechanism of selectivity using molecular dynamics simulations and unveil that the interactions between cations and the sluggish water confined to the pore, as well as cation-anion interactions, result in the different transport behaviors observed between ions.

Microporous membrane with ionized sub-nanochannels enabling highly selective monovalent and divalent anion separation

Membranes tailored for selective ion transport represent a promising avenue toward enhancing sustainability across various fields including water treatment, resource recovery, and energy conversion and storage. While nanochannels formed by polymers of intrinsic microporosity (PIM) offer a compelling solution with their uniform and durable nanometer-sized pores, their effectiveness is hindered by limited interactions between ions and nanochannel. Herein, we introduce the randomly twisted V-shaped structure of Tröger’s Base unit and quaternary ammonium groups to construct ionized sub-nanochannel with a window size of 5.89–6.54 Å between anion hydration and Stokes diameter, which enhanced the dehydrated monovalent ion transport. Combining the size sieving and electrostatic interaction effects, sub-nanochannel membranes achieved exceptional ion selectivity of 106 for Cl-/CO32- and 82 for Cl-/SO42-, significantly surpassing the state-of-the-art membranes. This work provides an efficient template for creating functionalized sub-nanometer channels in PIM membranes, and paves the way for the development of precise ion separation applications.

Perfect confinement of crown ethers in MOF membrane for complete dehydration and fast transport of monovalent ions.

Fast transport of monovalent ions is imperative in selective monovalent ion separation based on membranes. Here, we report the in situ growth of crown ether@UiO-66 membranes at a mild condition, where dibenzo-18-crown-6 (DB18C6) or dibenzo-15-crown-5 is perfectly confined in the UiO-66 cavity. Crown ether@UiO-66 membranes exhibit enhanced monovalent ion transport rates and mono-/divalent ion selectivity, due to the combination of size sieving and interaction screening effects toward the complete monovalent ion dehydration. Specifically, the DB18C6@UiO-66 membrane shows a permeation rate (e.g., K+) of 1.2 mol per square meter per hour and a mono-/divalent ion selectivity (e.g., K+/Mg2+) of 57. Theoretical calculations and simulations illustrate that, presumably, ions are completely dehydrated while transporting through the DB18C6@UiO-66 cavity with a lower energy barrier than that of the UiO-66 cavity. This work provides a strategy to develop efficient ion separation membranes via integrating size sieving and interaction screening and to illuminate the effect of ion dehydration on fast ion transport.

Toward Selective Transport of Monovalent Metal Ions with High Permeability Based on Crown Ether-Encapsulated Metal-Organic Framework Sub-Nanochannels.

Achieving selective transport of monovalent metal ions with high precision and permeability analogues to biological protein ion channels has long been explored for fundamental research and various applications, such as ion sieving, mineral extraction, and energy harvesting and conversion. However, it still remains a significant challenge to construct artificial nanofluidic devices to realize the trade-off effects between selective ion transportation and high ion permeability. In this work, we report a bioinspired functional micropipet with in situ growth of crown ether-encapsulated metal-organic frameworks (MOFs) inside the tip and realize selective transport of monovalent metal ions. The functional ion-selective micropipet with sub-nanochannels was constructed by the interfacial growth method with the formation of composite MOFs consisting of ZIF-8 and 15-crown-5. The resulting micropipet device exhibited obvious monovalent ion selectivity and high flux of Li+ due to the synergistic effects of size sieving in subnanoconfined space and specific coordination of 15-crown-5 toward Na+. The selectivity of Li+/Na+, Li+/K+, Li+/Ca2+, and Li+/Mg2+ with 15-crown-5@ZIF-8-functionalized micropipet reached 3.9, 5.2, 105.8, and 122.4, respectively, which had an obvious enhancement compared to that with ZIF-8. Notably, the ion flux of Li+ can reach up to 93.8 ± 3.6 mol h-1·m-2 that is much higher than previously reported values. Furthermore, the functional micropipet with 15-crown-5@ZIF-8 sub-nanochannels exhibited stable Li+ selectivity under various conditions, such as different ion concentrations, pH values, and mixed ion solutions. This work not only provides new opportunities for the development of MOF-based nanofluidic devices for selective ion transport but also facilitates the promising practical applications in lithium extraction from salt-like brines, sewage treatment, and other related aspects.

Freestanding two-dimensional nanofluidic membranes modulated by zwitterionic polyelectrolyte for mono-/di-valent ions selectivity transport

Effective separation of mono-/di-valent metal ions based on membrane technology is highly desirable in the energy storage and environmental protection field, but requires membranes capable of selective recognition of ions with similar nano-scale size. In this work, we designed and synthesized the sulfonate polyethylenimine (PEI-SO3H), as a zwitterionic polyelectrolyte, and integrated it into two-dimensional (2D) graphene oxide (GO) confined channels. Stable and sub-nanometer ion-selective transport channels enable fast transport of monovalent metal ions with high mono-/di-valent ion selectivity for K+/Mg2+ (12.2), Na+/Mg2+ (11.4) and Li+/Mg2+ (10.1) under electric field. Notably, the hydration compensation-promoting diffusion (HCPD) mechanism based on the synergistic effect of amino groups as compensation sites and sulfonic acid groups as recognition sites was proposed to understand the high-efficiency ion-selective transport process. In addition, instructed by abovementioned theory, the 2D vermiculite membrane was also designed to well realize the mono-/di-valent ions separation. This study provides a new strategy to construct freestanding 2D membranes with efficient ion-selective transport channels instructed by HCPD theory, which is expected to expand the potential for using membranes in the lithium extraction.

Water-coupled monovalent and divalent ion transport in polyviologen networks

Electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) revealed the ion-electron transport mechanism of viologen electrodes is dependent on anion valency, specifically the divalent sulfate ion exhibited mixed ion movement.

Rapid transport of water and monovalent ions through ultrathin polyamide nanofilms for highly efficient mono/bivalent ions separation

Defect-free ultrathin polyamide nanofilms enable superior separation performance, which can be prepared by interfacial polymerization (IP) at free oil–water interface (also known as support-free IP). However, the current free IP methods usually suffer from complicated process, or complex equipment. Herein, an easily-manufactured plate-and-frame assembly for free IP was designed for more efficient fabrication of ultrathin membranes. Piperazine (PIP)-based negatively-charged NF membranes were fabricated by this method, combining with introduction of a rigidly-contorted spirobisindane monomer that simultaneously enhanced the mechanical strength, microporosity, and electronegativity of membrane. The resulting defect-free ultrathin membranes not only exhibit super-high Na2SO4 rejection (∼99.7 %), and allow rapid transport of water and monovalent ions, thus leading to a Cl-/SO42- selectivity of up to 240. Furthermore, the polymerization of acyl chloride and macromolecule polyethyleneimine (PEI) at free oil–water interface was also investigated. The resulting positively-charged ultrathin membranes show outstanding calculated monovalent/bivalent cation selectivity (54.8 for Li+/Mg2+, 43.2 for Na+/Mg2+), further demonstrating the effectiveness of ‘thickness reduction’ strategy to enhance ions selectivity. In addition, the cause of different surface charge properties for PIP and PEI membrane system was revealed by molecular simulation.

Highly efficient monovalent ion transport enabled by ionic crosslinking‐induced nanochannels

AbstractCharge‐governed ion transport is of significant importance to industrial development, and advanced membrane materials with fast and selective ionic transport are essential components. In cell membranes, ionic transport is mainly determined by the charge‐governed protein channels, representing an architecture with functional differentiation. Inspired by this, a novel class of membranes was developed by ionically crosslinking sulfonated (poly[ether ether ketone]) and quaternized poly(2,6‐dimethyl‐1,4‐phenylene oxide) to construct the cationic conductive biomimetic nanochannels. Ionic crosslinking was tailored to realize nanophase separation and efficient ion transport mainly based on surface chemistry without altering the scaffold feature of polymeric pore channels. The best‐performing ionic crosslinking membrane exhibited a high ionic permeation (2.23 mol·m−2·h−1 for K+) and high cationic selectivity (7.91 for K+/Mg2+), which were comparable with the commercial monovalent cation permselective CIMS membrane, owing to the negligent surface resistance toward monovalent cations but strong positively charged repulsion against divalent cations.

Porous organic cage supramolecular membrane showing superior monovalent/divalent salts separation

Nanofiltration process has been perceived as one of the promising approaches in desalination and separation of monovalent/divalent salts. Despite significant progresses has been made in permeability and salt rejection, the industrial separation for monovalent/divalent salts is limited by the insufficient selectivity for ions with different charges and sizes. This work firstly proposed a porous organic cage supramolecular membrane with topologically structured “window-to-window” channels for the fast transport of monovalent ions and water molecules. Specifically, porous organic cage (RCC3) molecule and nonpolar alkyl of dodecyltrimethylammonium bromide (DTAB) were assembled into supramolecular RCC3@DTAB through hydrophobic interaction by molecular recognition of polar cavity. Furthermore, terephthaloyl chloride (TPC) was employed as a crosslinker by interfacial polymerization to construct RCC3@DTAB-TPC supramolecular film onto the surface of polydopamine modified polysulfone (PSf) substrate. The results suggested that RCC3@DTAB-TPC membrane displayed a high permeability of 13.9 L m−2 h−1 bar−1, and attractive performance for monovalent/divalent salts separation and small molecule solutions desalination. The salt rejections to Na2SO4, MgSO4, NaCl and MgCl2 are 98.5%, 90.1%, 19.8% and 12.8%, and the selectivities of NaCl/Na2SO4 and NaCl/MgSO4 reached 42.6 and 7.8, respectively. Besides, the separation factors for NaCl/medicine and NaCl/dye mixtures are 95.5 of δNaCl/DG and 76.6 of δNaCl/CR, respectively. The excellent separation performance of RCC3@DTAB-TPC supramolecular membrane provides a new idea for developing high-efficiency membranes for monovalent/divalent salts separation.

Highly efficient Li+/Mg2+ separation of monovalent cation permselective membrane enhanced by 2D metal organic framework nanosheets

Monovalent cation permselective membranes (MCPMs) manifest remarkable effectiveness and potential in lithium extraction whereas facing the challenge to achieve high permselectivity and high Li+ permeability simultaneously. In this work, Zn-TCPP, a kind of two-dimensional nanosheet with abundant negative charges, was successfully synthesized via surfactant-assisted method and introduced into surface cross-linked SPES membrane to fabricate MCPMs. The physicochemical properties, electrochemical properties and Li+/Mg2+ separation performance of resulted MCPMs were systematically estimated. As ions passing through the membrane, dense PVA/GA crosslinked layer separated Li+ and Mg2+ by pore-size sieving effect. Afterwards, uniformly distributed Zn-TCPP nanosheets with rich negative charges and physically adsorbed water molecules elevated the charge density and water content in the membrane and thus expedited Li+ transporting. Therefore, high Li+/Mg2+ permselectivity (PMg2+Li+= 8.99) and Li+ permeation flux (JLi+= 9.12 × 10−9 mol cm−2∙s−1) were obtained. Furthermore, membrane surface resistance was reduced from 108.99 Ω cm2 to 24.12 Ω∙cm2. This study points out the feasibility of the new method for accelerating monovalent ion transport and alleviating the restriction between ion permeation and permselectivity in selective ion exchange membranes.

Indications of ion dehydration in diffusion-only and pressure-driven nanofiltration

Recent insights into the permeation of small ions through polyamide membranes highlighted the role of ion dehydration in the transport and selectivity observed. However, such insights were a by-product of studies exploring different transport phenomena without a systematic methodology that focuses on ion dehydration itself. In this study, we quantified the intrinsic permeability and its underlying Eyring's enthalpy and entropy of activation for a systematic set of cations and anions in polyamide nanofiltration membranes to gain better understanding of ion dehydration. Our results in a diffusion-only system expose a distinct correlation between the hydration strength of the ions and the enthalpic barrier they experience during permeation, with a permeability order that is similar to the mobility order in solution. Smaller entropic losses are observed for smaller bare ions, indicating their higher freedom of motion after dehydration compared to larger bare ions. Comparing the measured activation enthalpies to quantum chemical calculations for the ions' hydration in solution suggests that ions are only partially dehydrated. Last, our simulated ion permeability at higher temperatures and experimental results in a pressure-driven system expose higher permeation rates with reversed ion-ion selectivity, indicating the activation of ion transport in the form of ion dehydration when additional energy is supplied. • Transport of monovalent ions is explored in diffusion-only and pressurized NF. • More strongly hydrated ions face higher enthalpic barrier during permeation. • Smaller bare ions face lower entropic losses during permeation. • Experimental barriers correlate to simulated stripping of 1–3 water molecules. • Diffusion-only and pressurized filtration expose reversed ion-ion selectivity.

Graphene oxide membrane regulated by surface charges and interlayer channels for selective transport of monovalent ions over divalent ions

Separation of ions has wide applications both in industry and health care. Among them, the separation of mono-/di-valent ions remains great challenging, even for highly efficient membrane separation technology. The emerging two-dimensional-material (typically, graphene oxide, GO) membranes have shown outstanding molecular separation performance such as for water desalination and gas separation, while unattractive permeance and/or selectivity for separating mono/divalent ions. In this work, we designed a new type of GO membranes to separate mono-/di-valent ions, in which rationally-selected polyelectrolyte coating was introduced to simultaneously tune the surface charge and interlayer channels of assembled GO laminate. The resulting positively-charged membrane surface showed stronger repulsive force towards divalent cations over monovalent cations according to the Coulomb’s law; meanwhile, the regulated interlayer channels rejected divalent cations over monovalent cations with smaller size. The ion transport mechanism was understood by mathematic models of ion diffusion and DLVO theory. By utilizing the synergistic effect of electrostatic interaction and size sieving, the designed GO membrane exhibited excellent separation performance for various mono-/di-valent ion pairs, including K+/Mg2+, Na+/Mg2+, Li+/Mg2+. Especially, the K+ transport rate of ∼ 0.29 mol m−2 h−1 and K+/Mg2+ selectivity of ∼ 116 are demonstrated in single-salt solution test, outperforming the-state-of-the-art 2D-material membranes. In mixed-salt solution test, the K+/Mg2+ selectivity reached 45 and good structural stability was displayed during 80 h continuous operation on the GO membrane. This facile polyelectrolyte coating approach provides a new avenue to develop high-performing 2D-material membranes for efficient separation of mono/divalent ions.

Separation of mono-/di-valent ions via charged interlayer channels of graphene oxide membranes

Separation of mono-/di-valent ions is widely used in the fields of energy security and environmental protection. Compared with traditional separation methods, membrane separation could achieve higher efficiency with less energy. In this work, we reported graphene oxide (GO) membrane with charged interlayer channels for separation of mono-/di-valent ions by utilizing the synergistic effect of size-sieving and electrostatic repulsion. Positively-charged polyethyleneimine (PEI) were introduced into the interlayer of negatively charged GO layers via layer-by-layer assembly. Characterizations indicated that the introduction of PEI not only controlled the charge property of the interlayer channels, but also increased the hydrophilicity of the membrane surface. The effects of the number of GO-PEI bi-layer, PEI concentration and salt concentration on the membrane performance for mono-/di-valent ions were systematically investigated. The optimal GO-PEI membrane with ∼100 nm thick exhibited K + , Na + , and Li + permeation rates of 0.474, 0.378, and 0.306 mol m −2 h −1 , as well as the selectivity for K + /Mg 2+ , Na + /Mg 2+ , and Li + /Mg 2+ of 33.8, 27.0, and 21.9, respectively. Density functional theory (DFT) was employed to understand the transport mechanism of charged interlayer channels for selective transport of monovalent ions over divalent ions. • Graphene oxide membrane with charged interlayer for mono-/di-valent ions separation. • Ion separation is realized by effect of size-sieving and electrostatic repulsion. • Outstanding membrane performance for K + /Mg 2+ separation.

Cation-Chloride Cotransporters, Na/K Pump, and Channels in Cell Water/Ionic Balance Regulation Under Hyperosmolar Conditions: In Silico and Experimental Studies of Opposite RVI and AVD Responses of U937 Cells to Hyperosmolar Media.

Studying the transport of monovalent ions across the cell membrane in living cells is complicated by the strong interdependence of fluxes through parallel pathways and requires therefore computational analysis of the entire electrochemical system of the cell. Current paper shows how to calculate changes in the cell water balance and ion fluxes caused by changes in the membrane channels and transporters during a normal regulatory increase in cell volume in response to osmotic cell shrinkage (RVI) followed by a decrease in cell volume associated with apoptosis (AVD). Our recently developed software is used as a computational analysis tool and the established human lymphoid cells U937 are taken as an example of proliferating animal cells. It is found that, in contrast to countless statements in the literature that cell volume restoration requires the activation of certain ion channels and transporters, the cellular responses such as RVI and AVD can occur in an electrochemical system like U937 cells without any changes in the state of membrane channels or transporters. These responses depend on the types of chloride cotransporters in the membrane and differ in a hyperosmolar medium with additional sucrose and in a medium with additional NaCl. This finding is essential for the identification of the true changes in membrane channels and transporters responsible for RVI and AVD in living cells. It is determined which changes in membrane parameters predicted by computational analysis are consistent with experimental data obtained on living human lymphoid cells U937, Jurkat, and K562 and which are not. An essential part of the results is the developed software that allows researchers without programming experience to calculate the fluxes of monovalent ions via the main transmembrane pathways and electrochemical gradients that move ions across the membrane. The software is available for download. It is useful for studying the functional expression of the channels and transporters in living cells and understanding how the cell electrochemical system works.

Boosting ion exclusion of two dimensional TMD lamellar membranes via in-plane engineering strategy

Transition metal dichalcogenide (TMD) derived stratiform membranes exhibit sub-nanometer scale interlayer distances and exceptional anti-swelling property in water environments but they are frustrated in ion rejections. Herein, the in-plane regulating concept to improve ion exclusion of TMD laminates was proposed. We demonstrate this concept using flexible and hydrophilic polyvinyl alcohol (PVA) polymers as the intercalators to implant TMDs. The resulting TMD/PVA membranes show obviously decreasing ion permeation. Taking the TaS2/PVA membrane as an example, its monovalent, divalent and trivalent ion transport rates reduce by 87, 131 and 168 times respectively compared with the pristine TaS2 membrane. Additionally, the ion permeation behaviors of TMD/PVA membranes reveal long-term and cyclic stability. For the practical desalination process under the forward osmosis mode, the TaS2/PVA membrane shows an extraordinarily high water flux of 3.9 L m−2h−1 together with a promising NaCl rejection of 98.7%, which is superior to the existing two dimensional membranes.

A continuum PNP model of double species ion transport between graphene

In this paper, we employ Poisson–Nernst–Planck equations in conjunction with the Navier–Stokes equations and the mean-field theory to investigate the charge transport of double species monovalent ions in double-layered graphene sheets, driven by an external electric field. Unlike most classical models, we develop a simple mechanical model by incorporating the microscopic effects of the physical systems so that the ionic interactions between ions and the host material, and the steric repulsions among ions are considered. Taking Li+-PF6−1 monovalent ions as an example, we find that the transport pattern for the present double species ionic systems and that for the pure lithium ions are dramatically different. Due to the mutual attractive ionic forces between ions and their counter-ions, such double species systems turn out to be more stable than that of the single species systems. In addition, the storage patterns of the former systems are richer, which depend heavily on initial ionic states, however less on the strength of applied electric fields and external temperatures when the graphene separation is not too large. The fluid flows, the electric conductivities and the stability of such double species systems are subsequently scrutinized. The current study could form a theoretical basis to help designing high-performance lithium batteries and explaining ion transport in biological channels.

Paracellular Gatekeeping: What Does It Take for an Ion to Pass Through a Tight Junction Pore?

Tight junction pores are physiological gatekeepers of paracellular transport in epithelial tissues. Conventionally, tight junction permeability is determined via in vitro electrophysiology measurements; however, the macroscopic readout does not provide molecular-level understanding into the mechanism of ion permeation. Insight into the factors governing selectivity across the paracellular space is just emerging. In this study, we investigated tight junction pores comprising of claudin-2 and claudin-5 proteins that are structurally similar to subnanometer radii but have measurably different in vitro ion permeabilities. To evaluate the mechanistic differences in ion transport across the pores, we computed the free-energy profiles and relative rate constants for the transport of monovalent (Na+, K+, Cl-) and divalent (Mg2+ and Ca2+) ions through the pores using replica exchange metadynamics. In claudin-2, we demonstrate how a single residue dictates selective permeability of Na+ and K+ ions. In claudin-5, we found no clear preference for anion or cation selectivity; thus, pores formed by claudin-5 are indeed barriers to ion permeation. Mutations to claudin-5 that widen the pore's steric radius did not significantly impact pore selectivity, indicating that electrostatics dominate pore selectivity. The key takeaways from this work are as follows: (a) two pores that are similar in diameter and length can have dissimilar ion conductance, (b) existence of a physical pore does not guarantee ion permeability, and (c) the electrostatic environment created by the pore-lining residues dictates the ion conductivity. These mechanistic understandings of the tight junction pores are critical for the interpretation of tight junction physiology.

Ion Homeostasis during the Growth of Human Mesenchymal Stem Cell Culture. II. Age-Related Changes in Cell K+ Content

Ionic homeostasis of human mesenchymal stem cells (MSCs) during their long-term cultivation was studied. It was found that, at early passages (second to fourth), the intracellular K+ content calculated for total cellular protein was almost 40% higher than in cells of the same clone after 12–15 passages. Under the same conditions, the intracellular Na+ content remains practically unchanged in MSCs with age. Flow cytometry assay of MSC proliferation at various passages revealed that a decrease in the intracellular K+ content correlated with the cell accumulation in the G1 phase of the cell cycle and was accompanied by a slower cell division. On the basis of data on monovalent ion transport in permanent cell lines of different origin, human stem cells as well as activated human lymphocytes, the mechanism of implication of K+ in the cell proliferation has been discussed. It is suggested that changes in cellular K+ content per total cell protein accompanying triggering or inhibition of cell proliferation show the involvement of K+ in the cell volume regulation. The high intracellular K+ content is important for successful proliferation of hMSCs, and the cell K+ content per cell protein is an informative test for assessing the functional status of stem cells in vitro.

Identification of key genes and pathways in human clear cell renal cell carcinoma (ccRCC) by co-expression analysis.

Human clear cell renal cell carcinoma (ccRCC) is the most common solid lesion within kidney, and its prognostic is influenced by the progression covering a complex network of gene interactions. In our study, we screened differential expressed genes, and constructed protein-protein interaction (PPI) network and a weighted gene co-expression network to identify key genes and pathways associated with the progression of ccRCC (n = 56). Functional and pathway enrichment analysis demonstrated that upregulated differentially expressed genes (DEGs) were significantly enriched in response to wounding, positive regulation of immune system process, leukocyte activation, immune response and cell activation. Downregulated DEGs were significantly enriched in oxidation reduction, monovalent inorganic cation transport, ion transport, excretion and anion transport. In the PPI network, top 10 hub genes were identified (TOP2A, MYC, ALB, CDK1, VEGFA, MMP9, PTPRC, CASR, EGFR and PTGS2). In co-expression network, 6 ccRCC-related modules were identified. They were associated with immune response, metabolic process, cell cycle regulation, angiogenesis and ion transport. In conclusion, our study illustrated the hub genes and pathways involved in the progress of ccRCC, and further molecular biological experiments are needed to confirm the function of the candidate biomarkers in human ccRCC.

Reaction of osmoregulatory system in juveniles of Russian sturgeon Acipenser gueldenstaedtii (Acipenseridae) on influence of comatotropin of carp Cyprinus carpio

For the first time by the example of juveniles of Russian sturgeon Acipenser gueldenstaedtii Brandt, the role of growth hormone of hypophysis in the osmotic regulation of acipenserids was studied, also the process of transformation of reserve chloride was described. In Russian sturgeon juveniles, administration of growth hormone of carp Cyprinus carpio at a dose of 1 mg per 1 g body weight causes changes in the fine structure of numerous reserve (undifferentiated) gill epithelial cells and thus stimulates their transformation into mature chloride cells involved in transport of monovalent ions. Increase in the number of chloride cells, on account of reserve cells, was accompanied by higher enzymatic activity of Na+/K+-ATPase in gill homogenates of the injected fish adapting to a hyperosmotic environment of salinity 12.5‰ (403 mosm/l) than in the intact fish under the same conditions but without hormonal treatment. Morphophysiological changes observed in the injected juveniles provided the more efficient dynamics of blood serum osmolarity under saline exposure than that in the intact fish. Their serum osmolality during the maximum rise (24 hours after the transfer of fish into the water of 12.5‰ salinity) was lower (p <0.01), than that of the intact fish. The inclusion of growth hormone in the osmoregulatory process was established.