Salt Absorption Research Articles

8-(4-Chlorophenylthio)-Guanosine-3′,5′-Cyclic Monophosphate-Na Stimulates Human Alveolar Fluid Clearance by Releasing External Na+ Self-Inhibition of Epithelial Na+ Channels

Salt absorption via alveolar epithelial Na(+) channels (ENaC) is a critical step for maintaining an airspace free of flooding. Previously, we found that 8-(4-chlorophenylthio)-guanosine-3',5'-cyclic monophosphate-Na (CPT-cGMP) activated native and heterologous ENaC. To investigate the potential pharmacological relevance, we applied this compound intratracheally to human lungs and found that ex vivo alveolar fluid clearance was increased significantly. Furthermore, this compound eliminated self-inhibition in human lung H441 cells and in oocytes expressing human αβγ but not δβγ channels. To further elucidate this novel mechanism, we constructed mutants abolishing (β(ΔV348) and γ(H233R)) or augmenting (α(Y458A) and γ(M432G)) self-inhibition. The mutants eliminating self-inhibition lost their responses to CPT-cGMP, whereas those enhancing self-inhibition facilitated the stimulatory effects of this compound. CPT-cGMP was unable to activate a high P(o) mutant (β(S520C)) and plasmin proteolytically cleaved channels. Our data suggest that elimination of self-inhibition of αβγ ENaC may be a novel mechanism for CPT-cGMP to stimulate salt reabsorption in human lungs.

Synthesis of Cationic and Ampholytic Starch Graft Acrylamide and their Aqueous Salt Absorption

Acrylamide was grafted onto starch using ceric(IV) ion as initiator. Starch–graft-polyacrylamide was then modified through Mannich reaction using formaldehyde and diethylamine to give poly(N, N′-[(diethylamino) methyl]-acrylamide). The modified-graft copolymer was quaternized using different reagents; methyl iodide, n-butylbromide, sodium chloroacetate and propane sultone to give cationic and ampholytic graft materials. The absorbing properties of the produced materials toward deionized water and aqueous salt solutions were investigated. Studies of the absorbing properties of polyampholytes have revealed that these materials do not shrink upon increasing salt concentration. Kinetics of swelling in deionized water is also discussed.

The phosphorylation of anti-adrenergic quaternary ammonium salts related to choline.

Abstract Quaternary ammonium salts related to choline with anti-adrenergic properties have been phosphorylated. The resulting betaines were used to investigate a possible means for improving the oral absorption of quaternary ammonium salts. One of these was converted to the α-glycerophosphate for similar study.

Plasmin activates human epithelial sodium channels in oocytes

Salt absorption via epithelial sodium channels (ENaC) is a rate limiting process that is driven by basolaterally located Na/K-ATPase in epithelial cells. In injured lungs, plasminogen activator inhibitor (PAI-1) level is extremely high, possibly eliminating plasmin content in lung edema fluid. Plasmin cleaved heterologous mouse γ ENaC (Passero CJ, et.al JBC 283:36586–36591, 2008). To examine the regulation of human ENaC by plasmin expressed in oocytes, we incubated oocytes with plasmin and evaluated ENaC activity using dual-electrode voltage clamp technique. We found that plasmin (10μg/ml for 1 hour) stimulates ENaC currents up to 13 fold (from −1656.58 ± 127 nA to – 21711.189 ± 1797 nA, N=8, P<0.05). Plasmin activates αβγ ENaC activity in a time-dependent manner with maximal activation in one hour. To identify the potential proteolytic domains in α and γ subunits, we applied plasmin to six deletion mutants, termed, αΔ173–178, αΔ201–204, αΔ432–444, γΔ131–138, γΔ178–193 and γΔ410–422. Interestingly, four deletion mutations (αΔ432–444, γΔ131–138, γΔ178–193 and γΔ410–422) lost their responses to plasmin. Furthermore, several critical amino acid residues are able to reduce the stimulatory effects of plasmin on ENaC, including γR135M, γR137M, γK179M and γk181M. Our results suggest that plasmin may up-regulate heterologous human αβγ ENaC channels via multiple proteolytic domains in both α and γ subunits. Supported by NIH grants HL87017 and HL95435.

Carl W. Gottschalk Distinguished Lecture of the American Physiological Society Renal Section

AnnouncementsCarl W. Gottschalk Distinguished Lecture of the American Physiological Society Renal SectionPublished Online:01 Apr 2011https://doi.org/10.1152/ajprenal.00098.2011This is the final version - click for previous versionMoreSectionsPDF (140 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmail Jeff Garvin, PhD, will present the Carl W. Gottschalk Lectureship at the annual Experimental Biology meeting on April 11, 2011, in Washington, DC. Dr. Garvin is a well-respected leader in renal physiology and hypertension, whose work has gained recognition over his career.Dr. Jeff. GarvinDownload figureDownload PowerPointDr. Garvin earned his PhD at Duke University under the mentorship of Dr. Lazlo Mandel. There he began his interest in ion transport, identifying sodium channels in the toad bladder and tongue. He then joined the lab of Mark Knepper, PhD at the National Institutes of Health (NIH) as a postdoctoral fellow. During this period, he carried out a series of very influential studies on ammonium transport in proximal tubules and thick ascending limbs. These studies established beyond any doubt that both renal tubule segments are capable of significant transport of ammonium ions. This was an extremely important set of observations, which added substantially to our understanding of renal acid base transport in the mammalian kidney.At NIH, he developed a myriad of technical skills, which provided a solid basis for his research career. However, his work generated from the perfusion of isolated rat proximal tubules in vitro has led to his most novel findings. In his first faculty position at Henry Ford Hospital in Detroit, Michigan, he focused on the regulation of solute and fluid transport in proximal tubule, thick ascending limb and collecting duct using the isolated, perfused tubule technique and cultured cell techniques. He has shown convincingly that angiotensin II stimulates salt and fluid absorption from the rat proximal tubule and that atrial natriuretic factor inhibits angiotensin II stimulated fluid absorption. Later, he focused on the roles of nitric oxide and superoxide in regulation of solute transport in the thick ascending limb (TAL). One of his most important discoveries was the novel observation that superoxide stimulates salt transport in the TAL. Subsequent studies have tested function in other nephron segments and have explored the regulation of tubuloglomerular feedback. All of these studies have derived from unique applications of difficult techniques to further understanding of salt and water handling by the nephron and how it affects systemic blood pressure.Dr. Garvin has published more than 110 studies and his work has been supported by numerous NIH grants. He presented the Dahl Lecture at the Council for High Blood Pressure Research meeting in 2005. He is currently an Associate Editor of the American Journal of Physiology-Renal Physiology and was Chair of the FASEB Summer Research Conference on Renal Hemodynamics in 2010. In addition, Dr. Garvin has mentored a productive group of trainees now working as independent scientists.Dr. Garvin is an outstanding scientist who continues to make important and novel discoveries in how the kidney regulates salt and water balance. The Renal Section is honored to have Dr. Garvin present the Gottschalk Distinguished Lecture for 2011.The Carl W. Gottschalk Lecture selection committee was composed of Bill Welch (Chair), Tom Kleyman, and David Pollock.This article has no references to display. Previous Back to Top Next FiguresReferencesRelatedInformation More from this issue > Volume 300Issue 4April 2011Pages F1044-F1044 Copyright & PermissionsCopyright © 2011 the American Physiological Societyhttps://doi.org/10.1152/ajprenal.00098.2011History Published online 1 April 2011 Published in print 1 April 2011 PDF download Metrics Downloaded 76 times

841 CIRCULATING LEVELS OF TNF-LIKE CYTOKINE 1A (TL1A) AND ITS DECOY RECEPTOR 3 (DCR3) IN NASH: MARKERS OF ADVANCED DISEASE

Background: FGF-19, a novel intestinal hormone, is secreted in the terminal ileum postprandially and during bile salt absorption. Non-alcoholic fatty liver disease (NAFLD) is common in obesity but the molecular mechanisms of NAFLD development in non-obese patients remain yet to be defined. FGF-19 might play a protective role in NAFLD by improving insulin sensitivity, increasing hepatic beta-oxidation and inhibiting lipogenesis. The aim of our study was to investigate FGF-19 serum concentrations in non-obese (BMI 30kg/m) patients and healthy volunteers in a fasted state and after a defined oral fat load. Patients and Methods: In total, 14 NAFLD patients (mean BMI 27.7 kg/m), 21 obese individuals and 16 healthy controls were recruited. FGF-19 levels were determined by ELISA after 10 hours of overnight fasting. Subsequently, all individuals received 1 g fat (Calogen) per kg body weight orally. FGF-19 serum concentrations were measured at baseline and after 2, 4 and 6 hours. No other food intake was permitted during this time but water was allowed ad libitum. Results: Basal serum FGF-19 levels in the fasted state do not differ between overweight NAFLD patients, obese subjects and normal controls. The oral fat load increases FGF-19 levels in all three groups. FGF-19 serum levels peak after 4 hours in all three groups and were highest in controls (378.9±202.1 pg/ml). In comparison to men, women display significantly higher FGF-19 levels after 6 hours (283.4±189.6 vs. 172.1±82.1 pg/ml, p < 0.05). Of note, non-obese NAFLD patients display the lowest FGF-19 levels at all time points. In particular, FGF-19 levels 2 hours post oral fat load are significantly lower (p = 0.004) in overweight NAFLD patients (143.7±61.4 pg/ml) as compared to both healthy volunteers and obese patients (287.4±177.7 pg/ml and 281.4±235.0 pg/ml respectively). Conclusions: We established an oral fat load test (“OFLT”), which demonstrated impaired FGF-19 release in non-obese NAFLD patients. The hepatic mechanisms consequences of impaired FGF-19 signaling require further investigation.

Specific features of the intestinal mucosa of obese Zucker rats

Metabolic syndrome is a group of obesity-related metabolic abnormalities that increase an individual’s risk of developing type 2 diabetes and cardiovascular disease. The obese Zucker rats (OZR) may represent a valuable animal model for studying several aspects of this increasingly prevalent problem in worldwide. In fact, the genetically obese (fa/fa) Zucker rats, due a recessive mutation of the leptin receptor gene (lepr), exhibit hyperphagia and develop hallmark features of metabolic syndrome, including hyperlipidemia, hypertension, insulin resistance, and increased adiposity and oxidative stress. Here, we report the preliminary results from our current studies aimed to investigate different metabolic markers in the OZR intestinal mucosa, compared with their lean counterparts (LZR). Starting from the important role attributed to carbohydrates in regulating the critical equilibrium of the intestinal environment, we applied lectin histochemistry to visualize the glycosylation pattern expressed in the OZR intestinal mucosa. The investigation was mainly focused to identification and in situ characterization of sialylated and fucosylated glycomponents which were directly demonstrated with SNA, MAL II, LTA, and UEA lectin binding. In addition, in order to look for additional and complementary information about sialic acid acetylation degree and sites, PNA and DBA lectin histochemistry was combined with sialidase predigestion, potassium hydroxide deacetylation, and differential periodate oxidation. As a parallel study, the distributional patterns of carbonic anhydrase (CA), the enzyme which is differently expressed in the gastrointestinal tract with several functions, such as regulation of cellular and extracellular acid-base homeostasis, salt absorption and fluid balance, were visualized. The immunohistochemical localization of the CA isoenzymes CAIV, CA IX, CA XII, and CA XIV was performed with the relevant specific antibodies. The complex of the data obtained suggest a marked modulation of the sialoglycoconjugate expression in the OZR intestinal epithelium, when compared with the LZR, to be considered as an interesting topic for further investigations.

The Role of Salt in the Pathogenesis of Fructose-Induced Hypertension

Metabolic syndrome, as manifested by visceral obesity, hypertension, insulin resistance, and dyslipidemia, is reaching epidemic proportions in the Western World, specifically the United States. Epidemiologic studies suggest that the increased prevalence of metabolic syndrome directly correlates with an increase in the consumption of fructose, mainly in the form of high-fructose corn syrup. This inexpensive alternative to traditional sugar has been increasingly utilized by the food industry as a sweetener since the 1960s. While augmented caloric intake and sedentary lifestyles play important roles in the increasing prevalence of obesity, the pathogenesis of hypertension in metabolic syndrome remains controversial. One intriguing observation points to the role of salt in fructose-induced hypertension. Recent studies in rodents demonstrate that increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload, thus setting in motion a cascade of events that will lead to hypertension. These studies point to a novel interaction between the fructose-absorbing transporter, Glut5, and the salt transporters, NHE3 and PAT1, in the intestine and kidney proximal tubule. This paper will focus on synergistic roles of fructose and salt in the pathogenesis of hypertension resulting from salt overload.

Dietary fructose, salt absorption and hypertension in metabolic syndrome: towards a new paradigm.

The worldwide increase in the incidence of metabolic syndrome correlates with marked increase in total fructose intake in the form of high-fructose corn syrup, beverage and table sugar. Increased dietary fructose intake in rodents has been shown to recapitulate many aspects of metabolic syndrome by causing hypertension, insulin resistance and hyperlipidaemia. Recent studies demonstrated that increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload and thus causing hypertension. The absorption of salt (sodium and chloride) in the small intestine is predominantly mediated via the chloride/base exchangers DRA (Down Regulated in Adenoma) (SLC26A3) and PAT1 (Putative Anion Transporter 1) (SLC26A6), and the Na(+) /H(+) exchanger NHE3 (Sodium Hydrogen Exchanger3) (SLC9A3). PAT1 and NHE3 also co-localize on the apical membrane of kidney proximal tubule. Luminal fructose stimulated salt absorption in the jejunum and kidney tubules, responses that were significantly diminished in PAT1 null mice. These studies further demonstrated that Glut5 (SLC2A5) is the major fructose-absorbing transporter in the small intestine (and kidney proximal tubule) and plays an essential role in the systemic homeostasis of fructose. Increased dietary fructose intake for several weeks upregulated the expression of NHE3, PAT1 and Glut5 in the intestine and resulted in hypertension in wild-type mice, a response that was almost abolished in PAT1 null mice and abrogated in Glut5 null mice. This article will discuss the interaction of Glut5 with salt-absorbing transporters and review the role of dietary fructose in enhanced salt absorption in intestine and kidney as it relates to the pathogenesis of hypertension in metabolic syndrome.

3D Gastric Computed Tomography as a New Imaging in Patients with Failure or Complication After Bariatric Surgery

The number of bariatric operations performed each year is increasing. As a result, a rising number of patients in possible need for revisional surgery are referred to bariatric surgeons. But the standard methods of evaluation are often insufficient, and the best strategy remains difficult to choose. In our centre, we have developed 3D gastric computed tomography with air (3D-GCT). The aim of this pilot study was to assess the usefulness of this new image modality as an aid in the decision-making process in patients with failure or complications after bariatric surgery. Twenty patients referred for failure or complications after various bariatric procedures were included in the study. 3D-GCT was performed on a multidetector CT scanner after absorption of effervescent salt diluted in 10 ml of water and IV injection of butylscopolamine. Thin-slice data were transferred to a dedicated 3D workstation creating three-dimensional volume-rendering images of the oesophagus, gastric cavities and anastomoses. The volume of the gastric pouches and the diameter of stoma or anastomoses were measured. No failure or complications were observed. In all patients, 3D-GCT resulted in very impressive precise 3D images of post-surgical anatomy of the stomach. Imaging findings allowed us to identify or to eliminate the common complications of each procedure with a good accuracy, resulting in an aid to choose the best strategy in each patient. In conclusion, our pilot study suggests that 3D-GCT is useful as a decision-making aid in patients with failure or complications after bariatric surgery.

Short-chain fatty acids and commensal microbiota in the faeces of severely malnourished children with cholera rehydrated with three different carbohydrates

Short-chain fatty acids (SCFAs) liberated by fermentation of complex carbohydrates might stimulate water and salt absorption, and provide energy. The aim of the study was to assess the number and proportion of faecal bacteria and the concentration of SCFAs of severely malnourished children with cholera receiving oral rehydration solution (ORS) containing glucose, amylase-resistant starch (ARS) or rice. Serial faecal samples were collected from 30 malnourished children with cholera until rehydration and partial nutritional recovery. SCFAs were identified and quantitated by high-performance liquid chromatography. In situ hybridization combined with flow cytometry was used to analyse the microbiota in the faeces. Before treatment the concentration of total SCFA in faecal sample of cholera children was found to be 4.7±0.6 mmol/kg and it increased steadily until 95.0±8.7 mmol/kg at day 28. Among different ORS groups, concentration was significantly higher in the Rice-ORS group at day 1 (P<0.011) and at day 2 (P<0.025). During recovery faecal output was significantly reduced and the number of bacteria also increased faster in the Rice-ORS group than in the glucose-ORS group at day 1 and day 2 (P<0.01), and a modest increase in bacterial number was observed in the glucose-ORS plus ARS group (day 1, P=0.07; day 2, P=0.09). Clinical recovery was associated with an increase in bacterial and SCFA concentrations with all three carbohydrates in ORS. However, the increases were significantly higher in children receiving Rice-ORS.

Green banana-supplemented diet in the home management of acute and prolonged diarrhoea in children: a community-based trial in rural Bangladesh

To determine the effectiveness of green banana in the home management of acute (<7 days) or prolonged (≥ 7 days) diarrhoea at the community level. A cluster randomized field trial was conducted among 2968 Bangladeshi rural children 6-36 months old. Wards (villages) were randomly assigned to either a standard care group or a standard care plus green banana group where mothers were instructed to add cooked green banana to the diets of diarrhoeal children. Through a village-based surveillance system, diarrhoeal morbidity data (severity, duration, compliance) were collected for 14 days. Treatment effects were determined by analysing cumulative probability of cure by testing Cox proportional hazards models and relative risk (RR). The cumulative probability of cure was significantly (P < 0.001) different in children receiving GB for both acute [hazard ratio (HR) = 0.63 (95% CI: 0.56-0.67)] and prolonged diarrhoea [HR = 0.38 (95% CI: 0.26-0.59)]. The recovery rates of children with acute diarrhoea receiving GB (vs. control) were significantly more by day 3: 79.9%vs. 53.3% [(RR) = 0.47, 95% CI: 0.41-0.55], (P < 0.001) and day 7: 96.6%vs. 89.1% (RR = 0.32; 0.22-0.46), (P < 0.001). Children with prolonged diarrhoea receiving green banana had significantly higher recovery rates by day 10: 79.8%vs. 51.9% (RR = 0.42; 0.23-0.73), (P < 0.001) and day 14: 93.6%vs. 67.2% (RR = 0.22; 0.08-0.54), (P < 0.001). A green banana-supplemented diet hastened recovery of acute and prolonged childhood diarrhoea managed at home in rural Bangladesh.

Alexander Beaumont Hope (1928–2008): an Australian biophysicist

Alex Hope was for many years a Foundation Professor of Biology in Biophysics and later Emeritus Professor at The Flinders University of South Australia. Throughout his career he strove to understand the energetics of plant cells, and devoted the latter two-thirds of his research career to the study of photosynthesis. His earlier, highly successful, research had focused on electrical properties and ionic relations of plant cells. The change of research direction, however, was only an apparent one, since a continuing theme was the role of electrochemical potential gradients in energy capture and conversion. His life work was ‘‘driven by electricity’’ (Hope 2002, 2004, 2006). Alex was born in Launceston (in Tasmania), the first Australian city to have hydroelectricity as early as 1895. Electricity was seemingly ‘‘in the air’’, as several members of his family appear to have made their careers based on electricity. Alex studied at The University of Tasmania, majoring in physics. During his Honours degree year in 1949, he chose to investigate the electric fields in and around plant roots and shoots, suggested by his supervisor Alexander Leicester McAulay as possibly contributing to developmental forces in plant growth. McAulay, Professor of Physics from 1926 to 1959 (and son of a professor of mathematics and physics), was almost certainly Australia’s first biophysicist, having pioneered the study of mutations caused in yeast by ultraviolet radiation. Decades later, Alex was instrumental in establishing in the Australian Society for Biophysics a prize for innovative biophysics to honour the memory of McAulay, helped by Alex’s generous personal donation in support of that prize. Reluctantly, Alex let the Australian Society for Biophysics extend the name of the prize to The McAulay–Hope Prize for Original Biophysics. In his PhD work (1950–1952), Alex continued under the supervision of McAulay to investigate the mechanism by which nutrient minerals entered plant roots, with financial support from an appointment as a Temporary Research Officer in the Commonwealth Scientific and Industrial Research Organisation (CSIRO) for the final 2 years. The CSIRO Division of Food Preservation and Transport, as it was then called, had a Plant Physiology Unit headed jointly by the influential (later Sir) R. N. Robertson (see Robertson 1992) and F. V. Mercer for the study of salt absorption by plant cells. Alex was appointed on the understanding that he would be available for future employment in the Division! W. S. Chow (&) Division of Plant Science, Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT 0200, Australia e-mail: Fred.Chow@anu.edu.au

An Analysis to the Driving Forces for Water and Salt Absorption in Roots of Maize Seedlings Under Salt Stress

When maize seedlings were subjected to salt stress, a decline in root xylem pressure was observed within seconds, followed by a gradual increase in Na + deposition in the seedlings. The magnitude of xylem pressure response was positively correlated with, but not proportional to the intensity of the stress. A continuous recording of the xylem pressure profile showed that self-regulation of the xylem pressure existed before and after the imposition of salt stress when the environmental conditions were relatively stable. The salt induced increase in xylem tension dominated the total water potential of the plant when the salt stress was mild, but the osmotic potential became more prominent when the NaCl concentration in the root bathing solution was raised to over 100 mol m −3. The average transpiration rate of the seedlings dropped by 40% when the NaCl concentration in the root ambient was increased to 150 mol m −3. Although salt stress resulted in the decline of both the xylem pressure potential and the osmotic potential in the root xylem, the changes in the total water potential of the root xylem solution were always smaller than the changes in the water (osmotic) potentials of the solution bathing the root. An analysis to the water relations of maize seedlings showed that not only the water potential components, but the radial reflection coefficient of the roots was also dependent on the level of salinity. When the NaCl level in the root bathing solution was raised from 25 to 150 mol m −3, the radial reflection coefficient of the root declined from 0.43 to 0.31. This small change resulted in a remarkable increase in the normalised relative NaCl absorption by 2.4 times, indicating that the radial reflection coefficient of root played a very important role in regulating the absorption of NaCl in maize seedlings under salt stress.

Bile salts and cholestasis

Bile salts have a crucial role in hepatobiliary and intestinal homeostasis and digestion. Primary bile salts are synthesized by the liver from cholesterol, and may be modified by the intestinal flora to form secondary and tertiary bile salts. Bile salts are efficiently reabsorbed from the intestinal lumen to undergo enterohepatic circulation. In addition to their function as a surfactant involved in the absorption of dietary lipids and fat-soluble vitamins bile salts are potent signaling molecules in both the liver and intestine. Under physiological conditions the bile salt pool is tightly regulated, but the adaptive capacity may fall short under cholestatic conditions. Elevated serum and tissue levels of potentially toxic hydrophobic bile salts during cholestasis may cause mitochondrial damage, apoptosis or necrosis in susceptible cell types. Therapeutic nontoxic bile salts may restore impaired hepatobiliary secretion in cholestatic disorders. The hydrophilic bile salt ursodeoxycholate is today regarded as the effective standard treatment of primary biliary cirrhosis and intrahepatic cholestasis of pregnancy, and is implicated for use in various other cholestatic conditions. Novel therapeutic bile salts that are currently under evaluation may also prove valuable in the treatment of these diseases.

Absorption and fluorescence spectra of hypericin sodium salt in complexes with albumins

The spectra of absorption and fluorescence of hypericin sodium salt (Na-Hy) in organic solvents and in complexes with human serum albumin, bovine serum albumin, and lipoproteins of low and high density have been studied. It was shown that, as the proton donor properties of the solvent enhance, the absorption and fluorescence maxima shift toward the blue region, and as the proton-accepting properties increase, the maxima shift toward the red region. The absorption spectra of complexes of Na-Hy with bovine serum albumin significantly differ from those of complexes of this ligand with human serum albumin, which is evidenced by a lesser width of absorption bands and a lower value of the Stokes shift. The positions of the absorption and fluorescence maxima and the value of the Stokes shift for the complex of Na-Hy with human serum albumin increases when D20 instead of common water is used as a solvent. It was concluded that H-bonds of hypericin play a significant role in the interaction with human serum albumin.

Primary cilium is required for vasopressin mediated aquaporin‐2 trafficking

The collecting duct cell lines PCDNA (cilia (−)) and BAP2 (cilia (+)/rescue) derived from a PKD mouse model (orpk mouse) were used to determine the role of the primary cilium in vasopressin (AVP) mediated aquaporin 2 (AQP2) trafficking and fluid absorption. With apical AVP addition, cilia (−) cells grown on impermeable supports demonstrated an increased net fluid absorption as evident by the formation of epithelial domes, which were not seen in cilia (+) cells. Immunofluorescence studies showed AQP2 localization along the ciliary shaft and in subapical membrane compartment in cilia (+). Moreover, after apical AVP treatment, there was an increase in AQP2 expression at the apical membrane in cilia (−) but not in cilia (+) cells. This was confirmed by biotinylation and Western blot analysis, which demonstrated an AVP induced elevated glycosylated form of apically located AQP2 in cilia (−) vs. cilia (+) cells. Interestingly, in cilia (−) cells there was evidence for basolateral membrane insertion of AQP2. In the absence of cilia, there appears to be an AVP mediated targeting of the V2 receptor to the apical membrane and enhanced AQP2 localization at both apical and basolateral membranes. Thus, we propose AQP2 trafficking requires a normal cilium and when absent, the collecting duct cells becomes dedifferentiate leading to enhanced salt and water absorption which may contribute to the hypertension observed in PKD patients.

Effects of pretreatments and salt concentration on rohu (Labeo rohita) roes for preparation of roe pickle.

In India, fish egg (roes) is the underutilized rich source of protein and essential fatty acids. An attempt was made to utilize the roes for the preparation of pickle product. Roes of rohu (Labeo rohita) were subjected to pretreatments such as pasteurization and blanching in varying molar concentrations of salt solutions to improve the texture and sensory quality. Losses in protein content and absorption of salt by roes were assessed in both pasteurized and blanched roes for processing them into roe pickle. The pasteurized roes were very soft coupled with high fishy odour. Roes blanched in 1M NaCl solution were found to be good in taste in terms of salt, minimum loss in protein content and reduced fishy odour. The blanched roes were used to prepare fish roe pickle. The pickle was analyzed for physico-chemical parameters, microbial and sensory quality during storage. The roe pickle packed in glass bottle was shelf-stable and scored good for sensory characteristics of flavour, texture, taste and overall acceptability during a storage period of 6 months at room temperature (28 ± 2°C).

Regulation of ENaC-Mediated Sodium Reabsorption by Peroxisome Proliferator-Activated Receptors

Peroxisome proliferator-activated receptors (PPARs) are members of a steroid hormone receptor superfamily that responds to changes in lipid and glucose homeostasis. Peroxisomal proliferator-activated receptor subtype γ (PPARγ) has received much attention as the target for antidiabetic drugs, as well as its role in responding to endogenous compounds such as prostaglandin J2. However, thiazolidinediones (TZDs), the synthetic agonists of the PPARγ are tightly associated with fluid retention and edema, as potentially serious side effects. The epithelial sodium channel (ENaC) represents the rate limiting step for sodium absorption in the renal collecting duct. Consequently, ENaC is a central effector impacting systemic blood volume and pressure. The role of PPARγ agonists on ENaC activity remains controversial. While PPARγ agonists were shown to stimulate ENaC-mediated renal salt absorption, probably via Serum- and Glucocorticoid-Regulated Kinase 1 (SGK1), other studies reported that PPARγ agonist-induced fluid retention is independent of ENaC activity. The current paper provides new insights into the control and function of ENaC and ENaC-mediated sodium transport as well as several other epithelial channels/transporters by PPARs and particularly PPARγ. The potential contribution of arachidonic acid (AA) metabolites in PPAR-dependent mechanisms is also discussed.

Preparation of Rice Based ORS by Solution Method

A new method has been established to make rice based ORS through absorption of salts in rice by soaking the rice in the solution of salts. The soaked rice was dried, fried, powdered and packaged. The rice powder thus prepared when mixed with water in the desired proportion, the suspensions contain Na + , K + and Cl - as prescribed. The process is named ‘solution method’ according to the preparation procedure. DOI: 10.3329/cerb.v13i2.3132 Chemical Engineering Research Bulletin 13 (2009) 47-50