Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Na2SO4”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2006

Soluble-insoluble-soluble transitions of aqueous poly(N-vinylacetamide-co-acrylic acid) solutions.

Several poly(N-vinylacetamide-co-acrylic acid)s with various copolymer compositions have been synthesized, and their unique phase-transition behavior in aqueous salt (Na2SO4 or NaCl) solutions was investigated. Copolymers containing more than 51 mol % N-vinylacetamide (NVA) show reentrant soluble-insoluble-soluble transitions with increasing temperature. The soluble-insoluble transition temperature (T(p1)) increased linearly with increasing NVA content, whereas the insoluble-soluble transition temperature (T(p2)) was almost constant irrespective of the NVA content. Potentiometric titration of the copolymer solutions suggested that the acrylic acid (AA) carboxyl groups form hydrogen bonds with the NVA amide groups even under soluble conditions. Dehydration of the NVA amides and their consequent hydrogen bonding with the AA carboxyl groups during the soluble-insoluble transition process was indicated by FTIR measurements. Addition of salt (Na2SO4 or NaCl) to the aqueous media reduces the solvent quality and enhances the intra- and interchain interactions of the copolymers. Thus, T(p1) was observed to decrease and T(p2) was observed to increase with increasing salt concentration. However, the addition of urea to the media reverses the concentration dependence of T(p1) and T(p2) by disturbing the intra- and interchain interactions of the copolymers.

Journal Article↗
PubMed2003

Mg-gluconate provides superior protection against postischemic dysfunction and oxidative injury compared to Mg-sulfate.

Cardioprotection by Mg Sulfate (MgSO4) during ischemia/reperfusion (I/R) is attributed largely to the Mg2+ cation. However, Mg-gluconate (MgGl2) may provide added benefit, possibly through its anion's antioxidant properties. Protective effects of both Mg-salts and their anions during 30 min global I and 50 min R were assessed in Langendorff-perfused (Krebs-Henseleit buffer) rat hearts. Recovery of function was compared between untreated hearts and those receiving supplement (2.4 mM MgGl2, MgSO4, or Na2SO4, or 4.8 mM NaGI) for 5 min prior to I and during the initial 30 min R. The final 20 min R was conducted without supplement. End diastolic pressure (EDP, mmHg) of the 50 min reperfused MgGl2 group (2.6) was lower than MgSO4 (16.2) and untreated (35.6) groups, and the NaGI group (25.2) was considerably lower than Na2SO4 (38.8). Recovery of developed pressure (% preischemic DP) at the onset of R for MgGl2 (74.9) was greater than MgSO4 (37.9) and untreated (33.2). After 50 min, MgGl2 (77.9) and MgSO4 (66.9) provided protection compared to untreated (51.8). In separate studies, ESR spin trapping with alpha-phenyl-N-tert-butylnitrone (3 mM PBN) showed that I/R alkoxyl radical production was reduced with MgGl2 (0.0 vs. 2.4 vs. 3.6 mM: 184 vs. 97 vs. 54.8 nM/g tissue x min) to a greater extent than seen with MgSO4 (3.6 mM: 108). Additional studies suggest that Gl(1-), unlike SO4(2-), may scavenge hydroxyl radicals, accounting for the added protection. MgGl2 treated hearts exhibited less postischemic dysfunction and oxidative injury compared to MgSO4, suggesting the contribution of Gl(1-) to cardioprotection.

Animals↗
PubMed1987

Glomerular filtration effects of acute volume expansion: importance of chloride.

The present studies were done to determine the effect on GFR of acute volume expansion (AVE) using solutions of various sodium salts and to explore if degree of tubuloglomerular feedback (TGF) activation plays a role in any GFR differences. Free-flow micropuncture and inulin clearance studies were combined to investigate anesthetized Munich-Wistar rats expanded to 10% body weight with isotonic solutions of NaCl, Ringers bicarbonate (RB), NaHCO3, Na acetate (NaAc) and Na2SO4 as well as euvolemic controls. In the clearance studies, AVE yielded per gram kidney weight GFR's greater than control (1009 +/- 51 microliter/min) in the NaCl and RB (chloride expanded) groups (1397 +/- 89 and 1389 +/- 64) microliter/min, respectively, P less than 0.05 vs. control) but not in the NaHCO3, NaAc, and Na2SO4 (non-chloride expanded) groups. Proximal minus distal single nephron GFR determinations (P-D), an estimate of the degree of TGF, were less than control 13.2 +/- 2.1 nl/min) in the NaCl and RB groups (4.1 +/- 0.7 and 5.3 +/- 1.9 nl/min, respectively, P less than 0.05 vs. control) but were not significantly different from control in any of the non-chloride expanded groups. Early distal (ED) fluid flow correlated positively with P-D in all groups. ED chloride concentration but not TCO2 nor osmolality correlated with P-D for all groups. The correlation was negative for control and chloride expanded groups and positive for non-chloride expanded groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The effects of oxygen solubility and high concentrations of salts on photosynthetic electron transport in chloroplast membranes.

Chloroplast membranes were isolated in different media containing Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid] and high concentrations of sorbitol (0.33 M), potassium citrate (0.75 M) or Na2SO4 (1.0 M). Due to the complexity of the media, the oxygen solubility is strongly modified by high concentrations of salts (oxygen solubility for 0.33 M-sorbitol, 0.21 mmol/litre; for 0.75 M-potassium citrate, 0.121 mmol/litre; and for 1.0 M-Na2SO4, 0.112 mmol/litre). The knowledge of these values is necessary to interpret the rate of O2 evolution. For thylakoids isolated in 'sorbitol buffer' and then tested in high concentrations of potassium citrate, a slight stimulation of O2 evolution is observed (143-173 mumol of O2/h per mg of chlorophyll a) with potassium ferricyanide as electron acceptor. When we monitor the potassium ferricyanide reduction, no stimulation of electron transport is obtained even if the observed phenomenon is identical with the Photosystem-II oxygen evolution. In the same experiments no stimulation of the photophosphorylation was recorded, but when thylakoids are directly isolated in 0.75 M-potassium citrate, O2 evolution, ferricyanide reduction and photophosphorylation are inhibited by high concentrations of salts. The behaviour of thylakoids seems to be influenced by their initial treatment.

Cell Membrane↗
PubMed1987

Comparison of arylsulphatases from Eimeria tenella (parasite) and chicken caecum (host).

Chicken caecal arylsulphatase was purified 700-fold by (NH4)2SO4 fractionation, concanavalin A-Sepharose and cyclic AMP-Sepharose chromatographies. The purified enzyme was a glycoprotein of Mr 97,000. It hydrolysed p-nitrocatechol sulphate, cerebroside 3-sulphate and ascorbic acid 2-sulphate and was strongly inhibited by Na2SO4 (Ki = 50 microM) and Na3PO4 (Ki = 20 microM). Arylsulphatase from Eimeria tenella sporozoites was purified 28-fold by (NH4)2SO4 fractionation. Arylsulphatase of E. tenella sporozoites was not a glycoprotein. It had an Mr of 49,000. It was inhibited by Na2SO4 (Ki = 300 microM), sodium phosphate (Ki = 90 microM) and heparin. It hydrolysed ascorbic acid 2-sulphate, but cerebroside 3-sulphate was not desulphated. The kinetic parameters of chicken caecal arylsulphatase were different from those of the E. tenella enzyme.

Animals↗
PubMed1982

Diagnostic enzymology of alpha-L-iduronidase with special reference to a sulphated disaccharide derived from heparin.

1. Iduronosyl anhydro[1-3H] mannitol 6-sulphate (IMs), iduronosyl anhydro [1 3H] mannitol, phenyl iduronide (PhI) and 4-methylumbelliferyl iduronide have been compared as substrates for the diagnostic estimation of alpha-L-iduronidase activity present in human leucocyte and cultured skin fibroblast homogenates. The pH profile of leucocyte and fibroblast iduronidase activity was dependent on substrate structure and concentration, the ionic strength and the nature of the buffer ion used in the assay mixture. 2. NaCl, KBr and Na2SO4 were shown to be parabolic competitive inhibitors of IMs activity, the Ki with fibroblast homogenates being 34, 13.4 and 0.22 mmol/l respectively. NaCl and KBr were shown to have a primary salt effect on the interaction between enzyme and substrate but Na2SO4 appeared to have a specific ion effect at a cationic binding site. 3. NaCl inhibited the hydrolysis of IMs at all pH values studied, whereas NaCl concentrations of 0.2 mol/l inhibited the hydrolysis of PhI at pH values below 3.8 but activated the enzyme at higher incubation pH values. 4. Cu2+ was shown to be a potent non-competitive inhibitor of IMs enzyme activity with an apparent Ki of approximately 0.02 mmol/l. The enzyme activity was inhibited by Fe2+ (Ki 4 mmol/l), Hg2+ and Ag+, but has no significantly been affected by other univalent or bivalent cations. 5. The presence of solvent and salt effects on apparent Km but not the Vmax. suggest that the binding of IMs to the enzyme involved charge neutralization, and it is inferred that two cationic binding sites are present at the active site. It is postulated that one site specifically binds to the iduronic acid carboxyl group, the other to the 6-sulphate of the anhydromannitol moiety.

Anions↗
PubMed2002

Respective effects of sodium and chloride ions on filament formation and growth and ethanol production in Zymomonas mobilis fermentations.

AIMS: To elucidate the separate effects of the cation and anion in Zymomonas mobilis cultures inhibited by NaCl. METHODS AND RESULTS: In batch cultures containing 0.175 mol l-1 NaCl, Z. mobilis developed filaments and growth and ethanol production were inhibited. Chloride ions (added as 0.175 mol l-1 NH4Cl) produced similar filamentous growth, while sodium ions at the same concentration (as Na2SO4) did not. Growth and ethanol production were more strongly inhibited by Na2SO4 than by NH4Cl. Ammonium and sulphate ions had no inhibitory effects at these concentrations. CONCLUSIONS: Filament formation in NaCl-inhibited Z. mobilis is due entirely to the chloride ion, while the sodium ion has the major effect on growth and ethanol production. SIGNIFICANCE AND IMPACT OF THE STUDY: To avoid filamentous growth, chloride ions should be excluded from ethanol fermentations employing Z. mobilis, e.g. sulphuric is preferable to hydrochloric acid when hydrolysing lignocellulosic substrates prior to fermentation.

Ammonium Chloride↗
PubMed1976

Ionic effects on the uptake of sulfonylurea (glibenclamide) by pancreatic islets.

The accumulation of glibenclamide was studied in the pancreatic islets of non-inbred ob/ob-mice. Microdissected islets were incubated in media of different ionic composition and the accumulation measured as the uptake of drug not accounted for by equilibration in the urea space. In 12 mM N-hydroxyethylpiperazine-N'-2-ethane sulphonic acid (HEPES) buffer the accumulation was only half of that in Krebs-Ringer bicarbonate buffer. Addition of 50 mM NaCl, Na2SO4, KCl, or LiCl to the HEPES buffer restored the accumulation to the level seen in Krebs-Ringer buffer. Studies with different concentrations of NaCl and Na2SO4 showed that the glibenclamide accumulation was sensitive to Na+ with little or no effect being attributable to the anions. CaCl2 or MgCl2 had much stronger effects than NaCl. It is concluded that cations participate in the binding of glibenclamide to beta-cells. The mechanism could be an increased ionic attraction between cell surfaces and hydrophilic regions of the drug, or a shielding of fixed surface anions allowing stronger hydrophobic interactions between drug and beta-cells.

Animals↗
PubMed2006

Effect of different non-chloride sodium sources on the performance of heat-stressed broiler chickens.

1. One hundred and eighty 1-d-old broiler chicks were used to evaluate the effect upon broiler performance during severely hot summer months of three different sodium salts: sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3) and sodium sulphate (Na2SO4), in starter and finisher diets having an identical electrolyte balance (DEB) of 250 mEq/kg. 2. The non-chloride sodium salts were added to contribute the same amount of sodium and were substituted at the expense of builder's sand in the basal diets containing common salt (NaCl) as Na and Cl source. 3. Each diet was fed to three experimental units having 15 chicks each until 42 d of age. Severe heat-stress conditions, maintained in the rearing room, were indicated by high average weekly room temperature (minimum 29.3 degrees C; maximum 38.0 degrees C). 4. Diets containing sodium salts gave better body weight gain, feed intake and feed to gain ratio than the control diet. Sodium salts also enhanced water intake as well as water to feed intake ratio. This effect was more pronounced in broilers fed NaHCO3 supplement (with NaCl in the basal diets). 5. The increased water intake resulted in lower body temperature in heat-stressed birds fed NaHCO3 supplemented diet than in birds fed other sodium salts. A lower mortality rate was noted with NaHCO3 (15.15%), Na2CO3 (13.64%) and Na2SO4 (15.15%) supplements than with the control (33.33%) treatment. 6. Better carcase and parts yield were observed in sodium supplemented broilers. Sodium salts reduced the alkalotic pH and enhanced the blood sodium content, which ultimately improved the blood electrolyte balance and overall performance of heat-stressed broilers. 7. Supplementing broiler diets with sodium salts improved the live performance of heat-stressed broilers and better productive performance was noted with NaHCO3 than other sodium supplements.

Animals↗
PubMed2003

Leaching behavior and ESEM characterization of water-sensitive mudstone in southwestern Taiwan.

This investigation attempts to understand the critical soluble salts in natural mudstone and the leaching, microstructural, and microchemical characteristics in soaked mudstone using scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDAX), X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), conductivity measurement, ion chromatography (IC), and environmental scanning electron microscopy (ESEM)/EDAX techniques. Natural mudstone probably includes soluble salts such as Na2SO4, NaCl, NaCO3, and CaCO3. The dissolution of Na2SO4 controls water-sensitive mudstone very susceptible to slaking and dispersion. ESEM micrographs clearly show evidence of mudstone-slaking during soaking since the visible pores are filled with small aggregative masses. A calcium-bearing precipitate from the soaked mudstone is speculated to be attributable to the decomposition of the hydrated product of the fresh mudstone.

Chemical Precipitation↗
PubMed2006

Notochordal cell produce and assemble extracellular matrix in a distinct manner, which may be responsible for the maintenance of healthy nucleus pulposus.

STUDY DESIGN: Analysis of proteoglycan synthesis, distribution and assembly of notochordal cells and small nucleus pulposus cells embedded in alginate beads and cultured in presence of [S]-Na2SO4. OBJECTIVE: To determine whether the degeneration of the nucleus pulposus of the intervertebral disc is associated with a change in the cell phenotype. SUMMARY OF BACKGROUND DATA: The loss of the notochordal cell from the nucleus pulposus is associated with ageing and disc degeneration. The reduction in their numbers after birth in humans and in the chondrodystrophoid dog has been suggested to result from cell death and replacement or differentiation by chondrocytes. The almost total disappearance of the notochordal cells in the nucleus pulposus correlates with early degenerative changes in the disc and a concomitant reduction in proteoglycan content, increased collagen, and loss of water content. The basic mechanism of this accelerated degeneration with ageing is poorly understood. METHODS: Nucleus pulposus and anulus fibrosus cells were isolated from the lumbar intervertebral discs of chondrodystrophoid and nonchondrodystrophoid dogs. The cells from the nucleus pulposus were further separated by size into notochordal cells and small nucleus pulposus cells. Cells were embedded in alginate beads and cultured in the presence of [S]-Na2SO4 to measure proteoglycan size, rate of synthesis, and distribution into the pericellular and intercellular compartments. RESULTS: Large notochordal cells in the nucleus pulposus of chondrodystrophoid dogs formed 13% of the cell population in young dogs and fell to 0.4% in adults, whereas they were the predominant cell type in the nonchondrodystrophoid dogs at all ages. These cells were capable of 1.5-fold greater rate of synthesis of proteoglycans than the small nucleus pulpous cells. Proteoglycans secreted by the large cells were evenly distributed between the pericellular and intercellular compartments,whereas the small cells distributed 3-fold more proteoglycan into the intercellular phase. By size exclusion chromatography, the proteoglycans synthesized by the small cells of the chondrodystrophoid dogs formed large-size aggregates (Kav = 0.1) within the pericellular region, which then moved to the intercellular region over 5 to 10 days. In contrast, proteoglycans secreted by the notochordal cells were capable of rapid migration to the intercellular phase before assembly into large-sized aggregates. The ability to form aggregates was independent of age of the animal. CONCLUSIONS: Our model shows that a change in intervertebral disc cell phenotype correlates with the grade of disc degeneration and that the notochordal cells synthesize proteoglycans, which exhibit delayed aggregation than those synthesized by the small nucleus pulposus cells. This implies that the cell type composition of the nucleus pulposus of the chondrodystrophoid and nonchondrodystrophoid dogs produces an extracellular matrix that is assembled in a distinct manner, which may affect tissue integrity.

Animals↗
PubMed1978

The steady-state kinetics of yeast phosphoglycerate kinase. Anomalous kinetic plots and the effects of salts on activity.

1. A re-investigation of the kinetics of yeast phosphoglycerate kinase in the direction of 1,3-bisphosphoglycerate formation has been carried out, covering a 1000-fold range in substrate concentrations. A variety of improved spectrophotometric and fluorimetric assay procedures have been used. 2. Kinetic plots proved to be non-linear for each variable substrate. A variety of checks have been carried out to show that this is not due to artifacts in the assay procedures or heterogeneity of the enzyme preparation. 3. The effects of a variety of salts on the activity of the enzyme have been examined. Most salts, especially those with multivalent anions, can cause activation of the enzyme, but inhibit at high concentration. 4. The salt effect is shown to be principally due to anions rather than cations, and not to ionic strength changes. Sulphate, as one of the most effective anions has been used in most comparisons. 5. Salt activation is steepest when the substrate concentrations are low; maximum activation has been about 5-fold with 0.2 mM MgATP and 0.2 mM 3-phosphoglycerate. Inhibition at the higher salt concentrations is strongest at the same substrate concentrations as when activation is steepest, indicating a link between the two effects. 6. The presence of 20 mM or more Na2SO4 converted non-linear kinetic plots to linear ones. A study of the kinetics in the presence of 40 mM Na2SO4 was interpreted in terms of a random sequential binding mechanism, with sulphate acting as a competitive inhibitor. 7. Possible explanations for these anomalous results are discussed in terms of several mechanisms which have been shown to apply in other systems.

Anions↗
PubMed1992

Salt dependence, kinetic properties and catalytic mechanism of N-formylmethanofuran:tetrahydromethanopterin formyltransferase from the extreme thermophile Methanopyrus kandleri.

N-Formylmethanofuran(CHO-MFR):tetrahydromethanopterin(H4MPT) formyltransferase (formyltransferase) from the extremely thermophilic Methanopyrus kandleri was purified over 100-fold to apparent homogeneity with a 54% yield. The monomeric enzyme had an apparent molecular mass of 35 kDa. The N-terminal amino acid sequence of the polypeptide was determined. The formyltransferase was found to be absolutely dependent on the presence of phosphate or sulfate salts for activity. The ability of salts to activate the enzyme decreased in the order K2HPO4 > (NH4)2SO4 > K2SO4 > Na2SO4 > Na2HPO4. The salts KCl, NaCl and NH4Cl did not activate the enzyme. The dependence of activity on salt concentration showed a sigmoidal curve. For half-maximal activity, 1 M K2HPO4 and 1.2 M (NH4)2SO4 were required. A detailed kinetic analysis revealed that phosphates and sulfates both affected the Vmax rather than the Km for CHO-MFR and H4MPT. At the optimal salt concentration and at 65 degrees C, the Vmax was 2700 U/mg (1 U = 1 mumol/min), the Km for CHO-MFR was 50 microM and the Km for H4MPT was 100 microM. At 90 degrees C, the temperature optimum of the enzyme, the Vmax was about 2.5-fold higher than at 65 degrees C. Thermostability as well as activity of formyltransferase was dramatically increased in the presence of salts, 1.5 M being required for optimal stabilization. The efficiency of salts in protecting formyltransferase from heat inactivation at 90 degrees C decreased in the order K2HPO4 = (NH4)2SO4 >> KCl = NH4Cl = NaCl >> Na2SO4 > Na2HPO4. The catalytic mechanism of formyltransferase was determined to be of the ternary-complex type. The properties of the enzyme from M. kandleri are compared with those of formyltransferase from Methanobacterium thermoautotrophicum, Methanosarcina barkeri and Archaeoglobus fulgidus.

Amino Acid Sequence↗
PubMed1995

Nickel/magnesium interactions in nickel-sensitive patients.

Experimentally demonstrated interactions between Ni2+ and Mg2+ were examined in human beings. 110 subjects patch-test-positive to 10 microliters aq. NiSO4 0.1 M were subdivided into groups of 30, 50 and 30 people. Each subgroup was tested to 10 microliters NiSO4 0.1 M solution as a control and to mixed solutions containing NiSO4 0.1 M together with, respectively MgSO4 0.1 and 0.3, 0.3 and 0.5 and 0.5 and 1 M. On increasing the applied concentrations of MgSO4, the % of patients with reduced or suppressed nickel reactions, with 1 exception, proportionally increased. The exception concerned testing with 0.5 M, where a paradoxically exacerbating increase in nickel reactions was seen in a majority of nickel-sensitive subjects. MgCl2 aq. at 0.3, 0.5 and 1 M concentrations was not able to reduce the cutaneous patch test positive reactions to NiCl2 0.1 M in 25 sensitive patients. On increasing the applied concentrations of MgCl2, both the number and intensity of patch test reactions to NiCl2 proportionally increased. A supposed rôle of the sulfate and chloride counterions in the penetration of nickel was examined in 30 NiSO4 5% patch-test-positive patients, testing to 10 microliters of aq. NiSO4 0.1 M, NiCl2 0.1 M, NiSO4 0.1 M + MgCl2 0.3 M, NiCl2 0.1 M + MgSO4 0.3 M, Na2SO4 0.3 M, NaCl 0.3 M, NiSO4 0.1 M + Na2SO4 0.3 M, NiCl2 0.1 M + NaCl 0.3 M. The findings suggest that the addition of sulfate or chloride to nickel could determine the formation of different Ni complexes directed toward different targets, one Mg(2+)-dependent, the other Mg(2+)-independent.

Adult↗
PubMed1979

Inter-relationship of sodium, chloride, bicarbonate and acetate transport by the colon of the pig.

1. Net transport of Na, Cl, HCO3 and acetate was examined in the temporarily isolated colon of conscious pigs weighing 46 +/- 8 kg. 2. The entire colon absorbs 4.1 ml. H2O, 0.8 m-equiv Na, 1.3 m-equiv acetate and secretes 0.5 m-equiv HCO3/min with a solution comparable to the normal contents. The absorptive capacity of the proximal and distal halves of the colon was comparable per unit dry weight of mucosa when each segment was presented with the same solution. 3. A series of studies using ion replacement solutions showed that net Na absorption and net HCO3 accumulation in the lumen solution were both increased in the presence of acetate. Cl absorption was independent of Na absorption and was accompanied by an equivalent net secretion of HCO3 in the absence of Na. When NaCl in the perfusion solution was replaced with Na2SO4, Na and HCO3 were absorbed at equal rates. 4. Final pCO2 values observed in NaCl and Na2SO4 solutions were greater than those observed in plasma while the pCO2 of the Na acetate solution after perfusion was reduced to values below plasma concentrations. 5. Results are consistent with the hypothesis that hydration of CO2 in the lumen solution or mucosal cell provides a continuous source of H ions for absorption of the more permeable undissociated acid. The evidence also suggests an additional source of H ions may be provided by a Na-H exchange process located in one of the limiting cell membranes.

Acetates↗
PubMed1999

Potassium secretion in rat distal colon during dietary potassium loading: role of pH regulated apical potassium channels.

BACKGROUND: Chronic dietary K+ loading increases the abundance of large conductance (210 pS) apical K+ channels in surface cells of rat distal colon, resulting in enhanced K+ secretion in this epithelium. However, the factors involved in the regulation of these K+ channels are at present unclear. AIMS: To evaluate the effect of dietary K+ loading on intracellular pH and its relation to large conductance apical K+ channel activity in surface cells of rat distal colon. METHODS/RESULTS: As assessed by fluorescent imaging, intracellular pH was higher in K+ loaded animals (7.48 (0.09)) than in controls (7.07 (0.04); p<0.01) when surface cells were bathed in NaCl solution, and a similar difference in intracellular pH was observed when cells were bathed in Na2SO4 solution (7.67 (0.09) and 6.92 (0.05) respectively; p<0.001). Ethylisopropylamiloride (EIPA; an inhibitor of Na+-H+ exchange; 1 microM) decreased intracellular pH when surface cells from K+ loaded animals were bathed in either solution, although the decrease was greater when the solution contained NaCl (DeltapH 0.50 (0.03)) rather than Na2SO4 (DeltapH 0. 18 (0.02); p<0.05). In contrast, EIPA had no effect in cells from control animals. As assessed by patch clamp recording techniques, the activity of large conductance K+ channels in excised inside-out membrane patches from distal colonic surface cells of K+ loaded animals increased twofold when the bath pH was raised from 7.40 to 7. 60. As assessed by cell attached patches in distal colonic surface cells from K+ loaded animals, the addition of 1 M EIPA decreased K+ channel activity by 50%, consistent with reversal of Na+-H+ exchange mediated intracellular alkalinisation. CONCLUSION: Intracellular alkalinisation stimulates pH sensitive large conductance apical K+ channels in rat distal colonic surface cells as part of the K+ secretory response to chronic dietary K+ loading. Intracellular alkalinisation seems to reflect an increase in EIPA sensitive Na+-H+ exchange, which may be a manifestation of the secondary hyperaldosteronism associated with this model of colonic K+ adaptation.

Amiloride↗
PubMed1979

Metabolic requirements for anaerobic active Cl and Na transport in the bullfrog cornea.

In the bullfrog cornea, the relationships between the rates of aerobic and anaerobic glycolysis and active Cl and Na transport were studied. In NaCl Ringer (glucose-free), the short-circuit current (SCC) declined much more slowly under aerobic than under anaerobic conditions. The aerobic lactate effluxes in glucose-free and glucose-rich NaCl Ringer were 0.08 and 0.23 micromol/h.cm2, respectively. The transition to anoxia caused these values to increase significantly and was accompanied by depletion of endogenous glycogen in glucose-free Ringer. In Na2SO4 Ringer, amphotericin B (10(-5) M) stimulation of the aerobic SCC was not dependent on the presence of glucose but under anoxia, SCC stimulation required glucose. In Na2SO4 (glucose-rich) Ringer, amphotericin B stimulated the aerobic lactate efflux from 0.26 to 0.36 mumol/h.cm2 and anoxia increased it to 0.55 micromol/h.cm2. In NaCl Ringer, the addition of either 0.5 mM adenosine or 1 mM ATP with 26 mM glucose restored the anaerobic-inhibited SCC and lactate efflux of glucose-depleted corneas. The results show that the reactions of glycolysis are a sufficient energy source for supporting active Na and Cl transport.

Amphotericin B↗
PubMed1976

Renal hydrogen ion secretion after release of unilateral ureteral obstruction.

The effect of 24 h of unilateral ureteral obstruction on HCO3 reabsroption and urinary acidification was studied in dogs. The postobstructed kidney (EK) had a significantly lower glomerular filtration rate and renal plasma flow than the contralateral kidney (CK). Urinary pH prior to HCO3 loading was significantly higher in the EK as was maximal HCO3 reabsorption. Saline loading depressed HCO3 reabsorption to the same degree in both kidneys. Urinary PCO2, during HCO3 loading, and during phosphate infusion, was significantly lower in the EK than the CK. Fractional Na excretion was significantly higher in the EK than the CK after deoxycorticosterone acetate administration. Na2SO4 administration enhanced acid excretion only in the CK. K excretion was significantly lower in the EK than the CK both during HCO3 loading and Na2SO4 administration. There was redistribution of cortical blood flow from the outer cortex toward the inner cortex in the EK as compared to the CK. There was no difference in plasma renin activity from both renal veins. These data demonstrate enhanced proximal H+ secretion (which is abolished by volume expansion) and impaired distal H+ secretion by the postobstructed kidney. The distal defect is likely an effect of a generalized disorder of distal transport in that both K secretion and steroid-responsive Na reabsorption were impaired in the postobstructed kidney.

Animals↗