Electrolyte Homeostasis Research Articles

Beyond Hot and Spicy: TRPV Channels and their Pharmacological Modulation.

Transient receptor potential vanilloid (TRPV) channels are part of the TRP channel superfamily and named after the first identified member TRPV1, that is sensitive to the vanillylamide capsaicin. Their overall structure is similar to the structure of voltage gated potassium channels (Kv) built up as homotetramers from subunits with six transmembrane helices (S1-S6). Six TRPV channel subtypes (TRPV1-6) are known, that can be subdivided into the thermoTRPV (TRPV1-4) and the Ca2+-selective TRPV channels (TRPV5, TRPV6). Contrary to Kv channels, TRPV channels are not primary voltage gated. All six channels have distinct properties and react to several endogenous ligands as well as different gating stimuli such as heat, pH, mechanical stress, or osmotic changes. Their physiological functions are highly diverse and subtype as well as tissue specific. In many tissues they serve as sensors for different pain stimuli (heat, pressure, pH) and contribute to the homeostasis of electrolytes, the maintenance of barrier functions and the development of macrophages. Due to their fundamental role in manifold physiological and pathophysiological processes, TRPV channels are promising targets for drug development. However, drugs targeting specific TRPV channels, that are suitable for drug therapy, are rare. Moreover, selective and potent compounds for further research at TRPV channels are often lacking. In this review different aspects of the structure, the different gating stimuli, the expression pattern, the physiological and pathophysiological roles as well as the modulating mechanisms of synthetic, natural and endogenous ligands are summarized.

The role of salt-inducible kinases on the modulation of renal and intestinal Na+,K+-ATPase activity during short- and long-term high-salt intake

Type 1 salt-inducible kinases (SIK1) has been shown to act as a mediator during the cellular adaptation to variations in intracellular sodium in a variety of cell types. Type 2 SIK (SIK2) modulates various biological functions and acts as a signal transmitter in various pathways. To evaluate the role of both SIK isoforms in renal and intestinal Na+,K+-ATPase (NKA) activity, we made use of constitutive sik1−/− (SIK1–KO), sik2−/− (SIK2–KO), double sik1−/−sik2−/− (double SIK1*2-KO) knockout and wild-type (WT) mice challenged to a standard (0.3% NaCl) or chronic high-salt (HS, 8% NaCl) diet intake for 48 h or 12 weeks.Long-term HS intake in WT was accompanied by 2-fold increase in jejunal NKA activity and slight (~30% reduction) decreases in NKA in the ileum and cecum; none of these changes was accompanied by changes in the expression of α1-NKA. The ablation of SIK1 and SIK2 prevented the marked increase in jejunal NKA activity following the long-term HS intake. The ablation of SIK1 and SIK2 in mice on a long-term HS intake impacted differently in the ileum and cecum. The most interesting finding is that in SIK2–KO mice marked reductions in NKA activity were observed in the ileum and cecum when compared to WT mice, both on normal and long-term HS intake.In summary, SIK1 or SIK2 ablation on chronic high-salt intake is accompanied by modulation of NKA along the intestinal tract, which differ from those after an acute high-salt intake, and this may represent an absorptive compensatory mechanism to keep electrolyte homeostasis.

Lean Mice Show Sex‐Specific Effects of Early Life Stress on Water and Electrolyte Homeostasis and Renal Function

Early life stress (ELS) is associated with increases in body mass index and systolic blood pressure in adult life, leading to obesity and obesity-induced hypertension, major risk factors for cardiovascular disease (CVD). Previously, we have shown that Maternal Separation and Early Weaning (MSEW), a model that mimics the effects of ELS observed in humans, exacerbates hypertensive stimuli responses in male and female mice. The aim of this study was to investigate the status of the water and electrolyte homeostasis (WEH) at baseline in mice exposed to MSEW. Therefore, we determined water intake and excretion, plasma and urinary electrolytes, glomerular filtration rate (GFR) and sodium transporters expression along the nephron in lean mice. MSEW litter pups were separated from dams from postnatal day (PND) 2 to 16, followed by early weaning on PND 17. Litters that remained undisturbed and were weaned on PND 21 served as controls. At weaning, mice were placed on a low-fat diet (LF, 10% Kcal from fat) for 12 weeks. Single mouse metabolic cages were used to measure water intake and urine excretion. GFR was measured using a transcutaneous technique. MSEW males fed a LF showed an increase in water intake compared to controls (4.14 ± 0.32 vs. 3.4 ± 0.36 mL/day respectively, P<0.05), urine excretion (1.01 ± 0.16 vs. 0.61 ± 0.07 mL/day, P<0.05), and potassium excretion (12.05 ± 2.48 vs. 7.29 ± 1.49 µmol/day/g BW, P<0.05). MSEW mice showed no differences in plasma sodium (165.16 ± 2.44 vs. 161.34 ± 2.67 mmol/L), plasma potassium (5.42 ± 0.19 vs. 5.86 ± 0.16 mmol/L) or sodium excretion compared to controls (3.65 ± 0.72 vs. 3.24 ± 1.43 µmol/day/g BW, respectively). In addition, MSEW males showed increased GFR compared to controls (1.12 ± 0.05 vs. 0.90 ± 0.03 mL/min/100g BW, P<0.05). Renal cortex NHE3 expression was increased in MSEW compared to control mice (7.74 ± 2.22 vs. 1.2 ± 0.25 2^ddCt, respectively, P<0.05) while NCC expression was decreased compared to controls (0.38 ± 0.13 vs. 1.25 ± 0.32 2^ddCt respectively, P<0.05). Yet, no significant changes between MSEW and control mice were found in renal transporters NKCC2 (0.91 ± 0.26 vs. 1.23 ± 0.29 2^ddCt, respectively), or in the ENaC subunits ENaCα (0.97 ± 0.09 vs. 1.12 ± 0.21 2^ddCt), ENaCβ (1.14 ± 0.13 vs. 1.14 ± 0.27 2^ddCt), and ENaCγ (0.88 ± 0.13 vs. 1.08 ± 0.17 2^ddCt). Lean female MSEW mice showed no significant differences in water intake, urine excretion, urinary potassium, GFR, or renal transporters expression. Both increased NHE3 and reduced NCC expression have been linked to a greater potassium waste. These results show that the MSEW effects on WEH in lean mice are sex-specific, where only male mice display hyperfiltration and alterations in specific renal transporters expression. Chronic hyperfiltration may result in kidney damage and over time, chronic kidney disease. This could be aggravated in animals exposed to a secondary stressor such as a high-fat or high-salt diet. Ongoing studies of plasma and urine osmolarity may provide insights into the potential mechanisms by which MSEW male mice show hyperfiltration in lean healthy and normotensive mice.

Role of Basolateral K ir 4.1/K ir 5.1 Channel in the Regulation of Electrolyte Balance and ENaC Activity in the Cortical Collecting Duct

Recent genetic studies identified a critical role of basolateral inwardly rectifying K+ (Kir) channels of the distal nephron in K+ homeostasis and blood pressure control, making these channels attractive targets for hypertension treatment. The main aim of the present study was to examine the effect of established and newly discovered inhibitors of basolateral Kir channels amitriptyline, fluoxetine, and VU0134992 on the epithelial sodium channel (ENaC) activity in the cortical collecting duct (CCD). We show that inhibition of heteromeric Kir4.1/Kir5.1, but not homomeric Kir4.1 channel, substantially suppressed both amiloride-sensitive equivalent short-circuit current in cultured polarized epithelial mCCDcl1 cells and single-channel ENaC activity in principal cells of rat and human CCD tubules. Using the combination of confocal microscopy, FluoVolt™ voltage-sensitive dye, and Fluo8HT Ca2+ dye, we show that acute application of amitriptyline or VU992 in concentrations that produce an inhibitory effect on Kir4.1/Kir5.1 channel resulted in substantial depolarization of cellular membrane potential and increase in intracellular Ca2+ level in mCCDcl1 cells that can explain a significant decrease of ENaC open probability without altering channel conductance induced by these drugs. Furthermore, we evaluated the effect of nonspecific Kir inhibitor amitriptyline on electrolyte homeostasis and apical Na+ transporters' expression in the distal nephron in Dahl salt-sensitive (SS) rats. The administration of amitriptyline for three days led to a significant drop in plasma K+, an increase in Na+ and K+ excretion, and diuresis. These changes were accompanied by the compensatory overexpression of ENaC and total and phosphorylated forms of thiazide-sensitive Na+-Cl-- cotransporter. Our data uncovered the putative mechanism of the impact of basolateral Kir4.1/Kir5.1 channel inhibition on ENaC activity and further emphasized a specific role of this channel in regulation of blood K+ level and electrolyte homeostasis.

Regulation of NOS3 by Novel Acetylation Sites

Nitric oxide (NO) is important for cardiovascular and renal health. NO is primarily produced via the enzymatically catalyzed reaction of L-arginine and oxygen to produce NO and L-citrulline by nitric oxide synthase (NOS) isoforms, NOS1, NOS2, and NOS3. NOS3 was first identified in the endothelium but is also present in the kidney epithelium. Endothelial NOS3 maintains cardiovascular health by preventing platelet aggregation, smooth muscle proliferation, and leukocyte adhesion. Epithelial NOS3 controls water and electrolyte homeostasis by regulating ion transporter activity along the nephron. NOS3 activity is tightly controlled by posttranslational modifications. While phosphorylation sites have been well characterized, less is known about regulation by acetylation. Lysine acetylation is a dynamic posttranslational modification observed in both the nucleus and cytosol to regulate intracellular signaling. Our lab and others have shown NOS3 to be regulated by multiple deacetylases. We therefore sought to uncover novel lysine acetylation sites on NOS3 which modulate its activity. Based on posttranslational modification prediction software we chose seven lysines to investigate: K486, K497, K504, K607, K610, K727, and K731. We hypothesized that deacetylation of any or all of these lysine sites increases NOS3-mediated NO production. In order to test this hypothesis, we created NOS3 constructs containing lysine to arginine mutations at these sites mimicking deacetylation. These plasmids were transfected into COS7 cells and expression was confirmed with Western blot. NO production was assessed by measuring nitrite accumulation in the media over 48 hours. Constructs containing either K486R, K497R, or K504R did not show a significant increase in NO production compared to WT (WT: 1703±499.3 pmol NO2/mg protein; K486R: 1984 ± 1003 pmol NO2/mg protein; K497: 1528 ± 1032 pmol NO2/mg protein; K504: 4337±576.7 pmol NO2/mg protein; p < 0.05 vs WT). However, mutations of four lysines, K607R, K610R, K727R, and K731R (K607/610/727/731R), dramatically increased NO production (21971 ± 1941 pmol NO2/mg protein; WT: 1703±499.3 pmol NO2/mg protein; p < 0.0001 vs WT). To further identify which of the four lysines are responsible for the observed phenotype, we made two new constructs containing either K607/610R or K727/731R. K607/610R was similar to WT (WT: 2271 ± 729.3 pmol NO2/mg protein; K607/610R: 3523 ± 805.8 pmol NO2/mg protein: p > 0.05), yet mutations of K727/731R demonstrated a large increase in NO production (9431 ± 1772 pmol NO2/mg protein; WT: 2271 ± 729.3 pmol NO2/mg protein; p<0.05). These studies suggest K727 and/or K731 is basally acetylated and deacetylation increases NO production uncovering novel posttranslational modifications which regulate NOS3 activity. Future studies will identify whether K727, K731, or both sites are responsible for the increase in NO production.

Spatial Transcriptomics of Supraoptic Nucleus and Paraventricular Nucleus of the Hypothalamus

Magnocellular neurosecretory cells (MNCs) in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus release oxytocin (OXY) and arginine vasopressin (AVP) into the peripheral circulation, playing a key role in the regulation of fluid and electrolyte homeostasis. Several groups have investigated transcriptomics in these regions; however, the data lack spatial context important for better understanding physiological functions of genes. Our study leverages spatially-resolved transcriptomics to visualize the relationship between cells, their gene expression profiles, and their relative locations within a tissue sample. Here, we use a novel spatial transcriptomics technology, Visium Spatial Gene Expression, manufactured by 10x Genomics to obtain spatially-resolved gene expression data for the SON and PVN of an adult male Sprague-Dawley rat. Briefly, a fresh frozen brain was sectioned at 10μm thickness to collect four sections (~4x4mm) containing SON and PVN regions. The tissue was then mounted and fixed on the capture areas of a Visium slide containing probes that bind mRNA. Next, hematoxylin and eosin (H&E) staining and high-resolution imaging of the slide was performed prior to tissue permeabilization. The permeabilization releases mRNA from cells that then binds to capture probes on the slide beneath the tissue. cDNA is then synthesized from captured mRNA from which sequencing libraries are prepared. Sequence data is then visualized, using 10x Genomics’ Space Ranger and Loupe Browser applications, to overlay spatial gene expression data with our H&E stained images. Foremost, our results show that gene cluster analysis successfully differentiated myelinated fiber tracts from nuclei and identified several distinct neuronal populations. Gene clusters overlaying fiber tracts contain glia-specific markers (e.g., Mbp and Gfap) and those overlaying SON and PVN regions contain neuron-specific markers (e.g., Syn1 and Nrgn). These data also have the resolution to resolve OXY- and AVP-specific clusters in the SON via targeted gene analysis, with anatomical distribution consistent with immunohistochemistry results for the regions. Additionally, our results show clustering of SON with magnocellular PVN, while parvocellular PVN was a different cluster. Differential expression analysis of these two clusters revealed relevant genes for the distinct regions and neuronal subpopulations in the top 20 globally distinguishing genes (e.g., Avp and Oxt for SON and magnocellular PVN cluster and Trh for parvocellular PVN cluster). This spatially-resolved transcriptomic data allows us to obtain whole transcriptomic data without sacrificing morphological context (e.g., SON and PVN regions). Future spatial transcriptomic studies can be used to investigate changes in MNC gene expression in terms of sex differences and disease models that can potentially inform cellular mechanisms involved in pathophysiology.

Do Counter‐Current Exchange and Glycosaminoglycan Buffering Contribute in Salt Storage in Skin of Rats?

We have previously shown that there is an osmolality and urea gradient from epidermis to dermis and subcutis. This gradient may be a result of the proposed counter-current mechanism for electrolyte homeostasis in skin. Our aims were to test whether there are gradients in salt concentration in skin generated by counter-current exchange and whether glycosaminoglycans (GAGs) can store sodium making it ‘inactive’ in relation to fluid exchange and thereby act as buffers during high salt intake. Sprague-Dawley rats were given low salt diet (LSD, <0.1% NaCl in chow and tap water), high salt diet (HSD, 8% NaCl in chow and 1% saline to drink), and DOCA-salt diet (50mg/week deoxycorticosterone acetate, 150mg/21 days and 1% saline to drink). Rats were randomly assigned to either LSD (n=15), HSD (n=7) or DOCA salt (n=8) diet for measurements of extracellular volume (ECV) in tangential sequential skin sections. Two weeks into the diet regimen the rats were anesthetized, neprectomized and given the extracellular tracer 51Cr-EDTA i.v. that was allowed 120 min circulation time. Directly thereafter, shaved back skin was further processed by cutting sequential sections of 40 µm (epidermis) and 100 µm (dermis and subcutis) thickness in a cryostat taking care to avoid evaporation. The skin sections were weighed and counted in a gamma counter and the extracellular volume found as the plasma equivalent space of 51Cr-EDTA. After counting, the samples were dried until constant weight, then eluted in ultrapure water for seven days. The eluate was analyzed in an ion chromatograph to determine sodium and potassium content in each layer. Sulfated GAGs were determined in whole skin, dermis and subcutis using Blyscan sGAG colorimetric assay to determine sGAG content. When relating sodium content to ECV we found that there was a gradient from epidermis to dermis, and that this gradient was more pronounced in the DOCA rats. The LSD group had a mean sodium of 332.7±194.3 mM in epidermis and 118.3±20.15 mM in the following layer at 140±mM, with corresponding concentrations of 219.2±52 mM and 121.1±41.4 mM in HSD, and 757.8±426.1 mM and 123.7±11.45 mM in DOCA. There was no difference in sulfated GAGs in skin between LSD, HSD and the DOCA salt group in any of the skin regions. Our results suggest that there may be a gradient of salt in the skin with a higher concentration in ECV in epidermis supporting the notion of a counter-current mechanism. However, our data do not support that an increased concentration of sulfated GAGs contribute to salt buffering during high salt conditions.

Hypertension due to loss of water

In the current issue of Acta Physiologica, two papers are published investigating the development of arterial hypertension under conditions of pathological loss of free water in two disease models. Kovaric et al 1 studied rats with chronic renal failure, shedding excessive free water via their remnant kidney due to a hypostenuric concentrating defect. Wild et al. 2 investigated a transgenic mouse model for psoriasis, losing free water via the psoriatic skin lesions. In both cases the animals displayed hypertension, cutaneous vasoconstriction, and metabolic adaptations towards enhanced production of urea and organic osmolytes typical for a phylogenetically ancient water conservation response termed aestivation 3 . The international consortia of investigators spearheaded by Titze, Karbach, and Kitada therefore conclude that in both cases the hypertension was due to cutaneous vasoconstriction in an attempt to limit epidermal water loss. Because in either case the hypertension was associated with loss of water, and thus with hypo- rather than hypervolemia, the authors argue, that this concept of pathogenesis of hypertension is antipodal to the classic view that relies on hypervolemia due to sodium retention.

Mechanistic interactions of uromodulin with the thick ascending limb: perspectives in physiology and hypertension.

Hypertension is a significant risk factor for cardiovascular disease and mortality worldwide. The kidney is a major regulator of blood pressure and electrolyte homeostasis, with monogenic disorders indicating a link between abnormal ion transport and salt-sensitive hypertension. However, the association between salt and hypertension remains controversial. Thus, there is continued interest in deciphering the molecular mechanisms behind these processes. Uromodulin (UMOD) is the most abundant protein in the normal urine and is primarily synthesized by the thick ascending limb epithelial cells of the kidney. Genome-wide association studies have linked common UMOD variants with kidney function, susceptibility to chronic kidney disease and hypertension independent of renal excretory function. This review will discuss and provide predictions on the role of the UMOD protein in renal ion transport and hypertension based on current observational, biochemical, genetic, pharmacological and clinical evidence.

Codonopsis Radix modulates water and electrolytes homeostasis in mice

Codonopsis Radix is a traditional Chinese medicine best known for its effects in treating digestive, cardiovascular, immunological and hematopoitic diseases. It also appears in the traditional Chinese medical prescriptions against ascites. However, the physiological effect and molecular mechanism of Codonopsis Radix in water and electrolytes homeostasis have not been well studied. We found that Codonopsis Radix decoction increased water intake and the urine volume, but decreased food intake in mice. The treatment significantly reduced angiotensin II receptor (AT1R) transcription and serum aldosterone level in animals, suggested perturbed function of renin-angiotensin system. RNAseq analysis of Codonopsis Radix treated NCI–H295R cells detected suppressed AT1R, SP1, and TEF transcription as well. Thus, Codonopsis Radix may regulate water and electrolytes homeostasis by affecting AT1R expression and aldosterone biosynthesis, possibly through downregulating SP1 and TEF transcription.

LIDDLE SYNDROME – DETECTION OF NOVEL MUTATION IN A FAMILY WITH HYPERTENSION

Abstract Objective: Liddle syndrome is a rare monogenic form of arterial hypertension with autosomal dominant inheritance. It is caused by mutation of genes coding one of three subunits of epithelial sodium channel (ENaC), which is located in distal nephron. Under physiological conditions, its expression and activity is regulated to maintain fluid and electrolytes homeostasis by reabsorbing Na+. Mutated channel cannot be degraded and therefore, it is accumulated on cell membrane; this results in enhanced sodium reabsorption. The most common clinical presentation of Liddle syndrome is early onset of hypertension, hypokalemia, suppressed plasma renin activity and low plasma aldosterone level. Up to now, 36 mutations causing Liddle syndrome were described. Design and method: Genetic assessment was performed in a Czech family of three generations (n = 14, see Figure) where hypertension and tendency to hypokalemia was present in several members. We used PCR amplification of specific alleles of SCNN1B and SCNN1G genes which was followed by Sanger sequencing. Results: We present a novel mutation causing Liddle syndrome: Tyr604∗ in beta-subunit of epithelial sodium channel. This mutation is supposed to generate a premature stop codon at position 604, resulting in truncated beta-subunit of EnaC. It was found in 7 members of the family: I-1, II-1 and 2, and III-1 to 4. Phenotypes of these subjects were different: from severe hypertension and hypokalemia (subjects I-1 and III-3, manifestation in 10 and 5 years, respectively) to normotension with normal potassium levels (III-1 and 2, now aged 8 and 10 years, respectively); however, all the seven subjects with mutation had hypoaldosteronism (serum level &lt; 0.13 ng/ml). Conclusions: A new mutation causing Liddle syndrome is described. It is manifested with different severity and mild forms that are not manifested in early childhood exist; thus, Liddle syndrome may be more frequent among adult hypertensive subjects than currently supposed. Proper diagnosis is important as the patients respond well to treatment with ENaC blocker amiloride.

Altered Electrolyte Homeostasis and the Severity of Dengue in Children

Altered Electrolyte Homeostasis and the Severity of Dengue in Children

Effects of molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, on sodium dynamics in hypertensive subtotally nephrectomized rats

Hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitors were developed for treatment of renal anemia. Patients applicable for HIF-PHD inhibitor treatment experience complications such as chronic kidney disease, whereby water and electrolyte homeostasis is disrupted. The effects of hypoxia-inducible factor stabilization on salt accumulation in the setting of reduced renal function remain unclear. In the present study, we investigated the effect of a HIF-PHD inhibitor, molidustat, on salt distribution and excretion in rats with subtotal nephrectomy-induced chronic kidney disease. Male Wistar rats were subjected to 5/6 nephrectomy. After confirming blood pressure elevation (>150 mmHg, at 4 weeks after surgery), rats were treated with molidustat. After 1 week of treatment, molidustat did not significantly improve blood cell volume or blood pressure. Distribution of sodium, potassium, and water in skin, carcass, and bone samples was not affected by molidustat. Furthermore, molidustat had no significant effect on urinary sodium excretion or concentration in response to acute oral salt loading (1 g/kg). In conclusion, molidustat did not affect distribution or excretion of salt in rats subjected to a model of nephron loss.

Особливості гормонального тестування тиреоїдної функції у пацієнтів із цукровим діабетом 1-го типу і хронічною хворобою нирок

Актуальність. Перебіг хронічної хвороби нирок (ХХН) може впливати на метаболізм тиреоїдних гормонів. Встановлено, що зниження ниркової функції може поєднуватися зі змінами функції щитоподібної залози (ЩЗ). Тиреоїдна дисфункція також має наслідки для ренального потоку крові, швидкості клубочкової фільтрації (ШКФ), канальцевого транспорту, електролітного гомеостазу та структури клубочків. Мета дослідження— визначити особливості функції ЩЗ у пацієнтів із цукровим діабетом (ЦД) 1-го типу та ХХН, на підставі чого розробити рекомендації щодо термінів гормонального тестування тиреоїдної патології. Матеріали та методи. З метою визначення оптимальних термінів гормонального тестування була проведена оцінка тиреоїдної функції у 121 пацієнта з ЦД 1-го типу та ХХН. Пацієнти з ЦД 1-го типу та ХХН були розділені на 3 групи: перша— 78 осіб із ШКФ ≤ 60 мл/хв/1,73 м2, група 2— 20 осіб, які отримують нирково-замісну терапію (НЗТ), група 3— 23 особи після трансплантації нирки (ТН) з адекватною функцією трансплантату (тривалість роботи ниркового трансплантату— 3,62 (1,47–4,28) року). Результати. У пацієнтів із ЦД 1-го типу та ХХН знижена діагностична цінність рівня тиреотропного гормону (ТТГ) у зв’язку з відсутністю відмінностей його значень при зниженні вільного тироксину (вТ4) і вільного трийодтироніну (вТ3). Найбільш чутливим маркером тиреоїдної дисфункції є вТ3. Генез тиреоїдних порушень у пацієнтів з ЦД 1-го типу та ХХН має неімунну природу. У пацієнтів із ЦД 1-го типу, які отримують НЗТ, після процедури гемодіалізу відбувається збільшення периферичних загальних вТ4 і вТ3, що обумовлює необхідність моніторингу функціональних порушень ЩЗ безпосередньо після проведення сеансу гемодіалізу. Після ТН відбувається відновлення нормальних значень індексу периферичної конверсії (ІПК) і вТ3 протягом 1–2 років залежно від тривалості отримання НЗТ. У пацієнтів із ЦД 1-го типу з тривалістю роботи ренотрансплантату більше трьох років відбувається збільшення ІПК, що характеризує дисбаланс периферичних тиреоїдних гормонів у бік зниження вТ3 при відносно стабільному вТ4. Висновки. Тиреоїдні дисфункції характерні для всіх стадій патологічного процесу при ХХН у пацієнтів із ЦД 1-го типу, включаючи пацієнтів на термінальній стадії і після успішної трансплантації нирки. Зміни тиреоїдних гормонів асоційовані з тривалістю НЗТ, тривалістю роботи ренотрансплантату, а також можуть потенційно впливати на виживання пацієнтів після ТН.

Bifunctional protein PCBD2 operates as a co-factor for hepatocyte nuclear factor 1β and modulates gene transcription.

Hepatocyte nuclear factor 1β (HNF1β) is an essential transcription factor in development of the kidney, liver, and pancreas. HNF1β-mediated transcription of target genes is dependent on the cell type and the development stage. Nevertheless, the regulation of HNF1β function by enhancers and co-factors that allow this cell-specific transcription is largely unknown. To map the HNF1β interactome we performed mass spectrometry in a mouse kidney inner medullary collecting duct cell line. Pterin-4a-carbinolamine dehydratase 2 (PCBD2) was identified as a novel interaction partner of HNF1β. PCBD2 and its close homolog PCBD1 shuttle between the cytoplasm and nucleus to exert their enzymatic and transcriptional activities. Although both PCBD proteins share high sequence identity (48% and 88% in HNF1 recognition helix), their tissue expression patterns are unique. PCBD1 is most abundant in kidney and liver while PCBD2 is also abundant in lung, spleen, and adipose tissue. Using immunolocalization studies and biochemical analysis we show that in presence of HNF1β the nuclear localization of PCBD1 and PCBD2 increases significantly. Promoter luciferase assays demonstrate that co-factors PCBD1 and PCBD2 differentially regulate the ability of HNF1β to activate the promoters of transcriptional targets important in renal electrolyte homeostasis. Deleting the N-terminal sequence of PCBD2, not found in PCBD1, diminished the differential effects of the co-factors on HNF1β activity. All together these results indicate that PCBD1 and PCBD2 can exert different effects on HNF1β-mediated transcription. Future studies should confirm whether these unique co-factor activities also apply to HNF1β-target genes involved in additional processes besides ion transport in the kidney.

Modulation of the rat angiotensin type 1a receptor by an upstream short open reading frame

The rat angiotensin type 1a receptor (AT1aR) is a peptide hormone G protein-coupled receptor (GPCR) that plays a key role in electrolyte homeostasis and blood pressure control. There is a highly conserved short open reading frame (sORF) in exon 2 (E2) that is downstream from exon 1 (E1) and upstream of the AT1aR coding region located in exon 3 (E3). To determine the role of this E2 sORF in AT1aR signaling, human embryonic kidney-293 (HEK293) cells were transfected with plasmids containing AT1aR cDNA with either an intact or disrupted E2 sORF. The intact sORF attenuated the efficacy of angiotensin (Ang) II (p < 0.001) and sarcosine1,Ile4,Ile8-Ang II (SII), (p < 0.01) to activate AT1aR signaling through extracellular signal-related kinases 1/2 (ERK1/2). A time-course showed agonist-induced AT1aR-mediated ERK1/2 activation was slower in the presence of the intact compared to the disrupted sORF [Ang II: p < 0.01 and SII: p < 0.05]. Ang II-induced ERK1/2 activation was completely inhibited by the protein kinase C (PKC) inhibitor Ro 31–8220 regardless of whether the sORF was intact or disrupted. Flow cytometric analyses suggested the intact sORF improved cell survival; the percentage of live cells increased (p < 0.05) while the percentage of early apoptotic cells decreased (p < 0.01) in cells transfected with the AT1aR plasmid containing the intact sORF. These findings have implications for the regulation of AT1Rs in physiological and pathological conditions and warrant investigation of sORFs in the 5′ leader sequence (5′LS) of other GPCRs.

A cross-sectional study on the prevalence of electrolyte abnormalities in multiple trauma patients in Hamedan, Iran.

IntroductionEvaluation of electrolyte status and homeostasis is one of the most important components of evaluation and treatment of critically ill patients, especially those with multiple trauma. Electrolyte imbalance can be associated with a bad prognosis and the need of specialized consultancy.AimThe aim of this study was to evaluate and determine the electrolyte status of patients with multiple trauma and evaluate the relationship of electrolyte disorders with patient outcome.MethodsIn this cross‐sectional study, 370 patients who were referred to the emergency department of Besat Hospital in Hamadan, Iran with multiple trauma were studied. Demographic parameters clinical characteristics such as blood pressure, heart rate, respiratory rate, consciousness score and body temperature, paraclinical characteristics including radiographic status, ultrasound, and electrocardiography and serum levels of sodium, potassium, creatinine, hemoglobin, hematocrit, and BUN and urine analysis was performed. Data regarding the discharge from emergency department or referral to other units were also complete in a questionnaire for each patient. Statistical analyses were performed using SPSSv24.ResultsThree hundred seventy patients with multiple trauma were studied where 73% of patients were men and 27% were women. One hundred ninety‐six patients were discharged from the emergency department, and 174 patients were referred to other units of the hospital. The most common electrolyte abnormalities were hypotension (62.7%), hypernatremia (9.5%), hypokalemia (6.8%), and hypercreatinine (4.6%). The results of independent t‐test showed that heart rate and potassium level were significantly higher in patients referred to other units than in patients discharged from the emergency department and respiratory rate and hematocrit were significantly lower in patients referred to other units.ConclusionHypotension, hypernatremia, hypokalemia, hypercreatinine, and abnormal urine analysis were more frequent in patients referred to other units than in patients discharged from the emergency department. These variables can be considered in predicting patient status for referral to other units and delayed hospital discharge.

Study of clinical profile of hyponatremia in elderly patients admitted to medical wards at Mandya institute of medical sciences, Mandya

Background: Hyponatremia is the most common electrolyte disturbance in geriatric age group owing to impaired ability to maintain water and electrolyte homeostasis and it contributes to substantial morbidity and mortality. The etiology is multifactorial. Hyponatremia may be euvolemic, hypovolemic or hypervolemic with euvolemic being the most common and most of the patients presents with nonspecific symptoms. As aggressive or inappropriate therapy of hyponatraemia can be more harmful than the condition itself, clinicians should be familiar with the diagnosis and management of various forms of hyponatraemia in order to deliver precise management. The aim is to assess the clinical profile of hyponatremia in medically ill patients, its etiology and associated morbidity and mortality.Methods: This study was a hospital based retrospective cross sectional observational study involving 150 patients aged ≥60 years presenting with signs and symptoms of hyponatremia confirmed by lab investigations (plasma sodium &lt;135 meq/l) admitted to medical ward of tertiary care hospital of MIMS, Mandya from April 2019 to March 2020.Results: The most frequent symptom of presentation was nausea and vomiting (38.66%) and most of the patients had a euvolemic hydration status.Conclusions: The study thus focus the need for appropriate and timely diagnosis for reducing the associated morbidity and mortality associated with hyponatremia.

Epithelial and Endothelial Expressions of ACE2: SARS-CoV-2 Entry Routes.

Angiotensin converting enzyme 2 (ACE2) is a main receptor for SARS-CoV-2 entry to the host cell. ACE2 is one of the key enzymes in renin-angiotensin system and plays a vital role in the maintenance of cardiovascular function. ACE/ACE2 balance is critical in the regulation of blood pressure, electrolyte homeostasis, vascular and cardiac remodeling and inflammation. ACE2 was shown to be abundantly present in human epithelial cells of the lung and enterocytes of the small intestine as well as in endothelial cells of the arterial and venous vessels. ACE2 and TMPRSS2 are colocalized on the cell surface and produced a critical step host cell entry of SARS-CoV-2. TMPRSS2-cleaved ACE2 permits SARS-CoV-2 host cell entry however, ADAM17-cleaved ACE2 produces protective effects in several organs. Differently, basigin (CD147) was suggested as a putative alternate receptor for SARS-CoV-2 entry into endothelial cells. The intestinal ACE2 receptor is associated with the neutral amino acid transporter B0AT1 and ACE2 is necessary for the expression of this transporter on the luminal surface of intestinal epithelial cells. There is a good association between the localization of SARS-CoV-2 binding receptor ACE2 and the disease target organs in respiratory, cardiovascular and gastrointestinal systems. Decreased expression of ACE2, being a receptor for coronavirus, would prevent cellular entry of the virus thereby reducing progression of the infection. However, increased ACE2 expression produces beneficial health effects. Further studies are needed to clarify this conflicting situation. Currently, it is recommended to continue the therapy with ACE2-increasing drugs in patients with COVID-19.

Hyperaldosteronismus

Aldosterone is produced in the adrenal cortex and governs volume and electrolyte homeostasis. Hyperaldosteronism can occur either as primary aldosteronism (renin-independent) or secondary aldosteronism (renin-dependent). As the commonest cause of secondary hypertension, primary aldosteronism is associated with increased cardiovascular risk. Its most prevalent subtypes are aldosterone-producing adenomas as the most frequent unilateral form and bilateral hyperaldosteronism. Unilateral hyperplasia, familial hyperaldosteronism and aldosterone-producing carcinoma are rare. The aldosterone/renin ratio serves as ascreening parameter for primary aldosteronism. If this ratio is elevated, confirmatory testing and adrenal imaging are performed. Adrenal venous sampling is considered the gold standard for the distinction of unilateral from bilateral disease. Unilateral disease can potentially be cured by adrenalectomy, whereas patients that are not candidates for surgery or have bilateral disease are treated with mineralocorticoid receptor antagonists. Over the past 10years, somatic mutations in ion channels or transporters have been identified as causes of aldosterone-producing adenomas and so-called aldosterone-producing cell clusters (potential precursors of adenomas and correlates of bilateral hyperplasia, but also of subclinical hyperaldosteronism). In addition, germline mutations in overlapping genes cause familial hyperaldosteronism. Secondary hyperaldosteronism can occur in patients with hypertension treated with diuretics or in renal artery stenosis.