Presence Of Bicarbonate Ions Research Articles

Adsorption of uranyl species from bicarbonate solution onto hematite particles

The adsorption of uranyl species onto a well-characterized hematite sol has been studied in the presence of bicarbonate ions. The uptake of uranium decreases abruptly with increasing solution pH. The decrease coincides with a decrease in the proportion of (UO 2) 2CO 3(OH) 3 − present. Increasing the adsorption temperature from 25 to 60°C alters little the adsorption behavior. Results of electrophoretic mobility studies suggest that more than one uranium species may be involved in the adsorption and that the adsorbed species are negatively charged. Fourier Transform Infrared spectrum of the adsorption products show that carbonate groups are present, indicating that uranium is retained as carbonate complexes.

Establishing the direct-potentiometric "normal" range for Na/K: residual liquid junction potential and activity coefficient effects.

The observed reference ranges for sodium and potassium as determined by direct potentiometry vary from instrument to instrument, depending on the composition of the calibration standards. To resolve the existing confusion as to which reference intervals are most appropriately considered "normal," we propose a straightforward convention (based on plasma-water concentration units) in which the difference between direct (undiluted sample) and indirect (diluted sample) methodologies is accounted for by the volume displacement effect of proteins, lipids, and other dissolved substances in a typical plasma sample. Thus, the proposed reference intervals for sodium and potassium are approximately 7% greater by direct potentiometry than by procedures involving dilution. Data consistent with this convention can be obtained with a variety of aqueous-based calibrants, provided care is taken to minimize the errors resulting from activity coefficient and liquid junction potential effects. Additional experimental results are presented to show that these effects also account for the apparent suppression of the sodium ion concentration observed in the presence of bicarbonate ion.

Regulation of glucose utilization in chick embryo fibroblasts by bicarbonate ion.

The amount of glucose consumed by chick embryo fibroblasts in primary culture is strongly influenced by the presence of bicarbonate ion in the culture medium. Cells grown on glucose at physiologic concentration (5.5 mm) and in the absence of bicarbonate ion have a reduced rate of glucose utilization when compared to their counterparts cultivated in medium containing the usual 25 mM bicarbonate. The presence or absence of bicarbonate is without effect on chick embryo fibroblast proliferation over a 6-day growth period. Both lactic acid accumulation per mole of glucose consumed and the utilization of glutamine increase as a function of bicarbonate ion in the growth medium.

Active sulfate reabsorption in the proximal convolution of the rat kidney: specificity, Na+ and HCO3- dependence.

Using the standing droplet technique in the proximal convolution and simultaneous microperfusion of the peritubular capillaries, the decrease in luminal sulfate concentration with time and the zero net flux transtubular concentration difference of sulfate (delta CSO42-) at 45 s was determined - the latter being taken as a measure of the rate of active sulfate reabsorption. Starting with 0.5 mmol/l sulfate in both perfusates the delta CSO42- value of 0.35 mmol/l was approached exponentially with a half value time of 4.3 s. The delta CSO42- values in the early proximal and late proximal convolution did not deviate from each other. If the Na+ concentration in the perfusates was reduced, the delta CSO42- approached zero and extrapolated to a slightly negative value (Ci greater than Co). When 1 mmol/l ouabain was added to the perfusates delta CSO42- decreased by 66% (the latter experiments were performed in the golden hamster which is more sensitive to ouabain than the rat). 1 mmol/l thiosulfate diminished delta CSO42- by 68% and 1 mmol/l molybdate by 24%. Omitting or replacing bicarbonate by HEPES or glycodiazine reduced the sulfate reabsorption significantly, while acetazolamide (0.1 mmol/l) and increasing the CO2-pressure from 4.66 to 14.0 kPa (i.e. 5-15% CO2) had no effect. SITS 1 mmol/l had no effect on sulfate reabsorption. The data indicate that the sulfate reabsorption is driven by a Na+ gradient and inhibited by thiosulfate and molybdate, i.e. molecules which have a similar tetrahedral molecule structure. The sulfate reabsorption depends in an undefined manner on the presence of bicarbonate ions.

Reduction of ferrihemoglobin in erythrocytes of birds and mammals

1. 1. Species differences exist in ferrihemoglobin reduction rates in bird and mammalian red cells, bird erythrocytes being very active reducers. 2. 2. Glucose and lactate enhance ferrihemoglobin reduction. In horse and quail red cells β-hydroxybutyrate has this effect as well. 3. 3. Malate and pyruvate do not enhance ferrihemoglobin reduction. 4. 4. Plasma addition to red cell suspensions enhances ferrihemoglobin reduction; addition of lactate mimics this effect in all species except the dog. 5. 5. Incubation conditions are very important for measuring ferrihemoglobin reduction. Especially the presence of bicarbonate ions is essential. In our experiments no inhibition of reduction rates by chloride ions is found. 6. 6. Mitochondrial NADH production does not play a role in ferrihemoglobin reduction in bird red cells.

Regulation of glucose transport in chick fibroblasts: bicarbonate, lactate and ascorbic acid.

The rate at which chick embryo fibroblasts in primary or secondary culture transport glucose or 3-O-methyl glucose is strongly influenced by the presence of bicarbonate ion in the culture medium. Cells growing or maintained on glucose at physiologic concentration (5.5 mM) have an 8 to 10 fold higher rate of glucose uptake than their counterparts cultivated without bicarbonate. These cells also produce more lactate as a consequence of their more rapid intake of glucose. The hydrogen acceptors, methylene blue and dehydroascorbate added to the culture medium reduce the cell capacity to transport glucose and 3-O-methyl glucose to levels obtaining in the bicarbonate-free medium. There is a concomitant reduction in glucose utilized by cells during 24 hours and further reduction in lactate formed per molecule of glucose metabolized.

Mass transfer of CO 2 across membranes: Facilitation in the presence of bicarbonate ion and the enzyme carbonic anhydrase

A theoretical and experimental analysis of facilitated transport of CO 2 across membranes containing NaHCO 3 and the enzyme carbonic anhydrase (carbonate hydro-lyase EC 4.2.1.1) is presented. The necessary diffusion reaction equations are derived and the system constraints defined. For the CO 2HCO 3 − system, mathematical simplifications based on the magnitude of various reaction and concentration terms are made to make the equations tractable to solution. The resultant equations are solved by a number of analytical and numerical techniques, each having a limited, though useful, range of validity. The experimental arrangement consists of a liquid membrane (created by soaking a porous filter paper in the test solution), a diffusion chamber, and gas metering and analysis equipment. Conditions were selected to cover the range from diffusion- to reaction-dominated behavior. The flux of CO 2 across a membrane containing 1 M NaHCO 3 was measured at various partial pressures of CO 2 (2–28 in Hg) and with membrane thicknesses of 0.02, 0.06 and 0.10 cm. The extent of facilitation (defined as the ratio of reaction-related flux to the expected Fick's Law flux in the absence of reaction) ranged from near zero to nearly 5 in these experiments. The agreement between model calculations and experimental observation was found to be excellent over the entire range of near-diffusion to near-equilibrium behavior. In the presence of enzyme carbonic anhydrase (0.10 mg/ml, activity approx. 80%) and 1 M NaHCO 3, the CO 2 flux across a 0.02 cm membrane was 3–10-fold higher than the corresponding flux in the absence of enzyme. From experiments at various enzyme concentrations and membrane thicknesses, it appeared that the apparent CO 2 reaction rate was directly proportional to the enzyme concentration. The model calculations for the enzyme-catalyzed reactions agreed with the experimental observations to within ±10%.

Studies on the Mechanism of Activation of Adipose Tissue Pyruvate Dehydrogenase by Insulin

Abstract Incubation of rat epididymal adipose tissue fragments with insulin led to increases of up to 2.4-fold in the activity of pyruvate dehydrogenase subsequently assayed in tissue homogenates. The activation of pyruvate dehydrogenase by insulin was greatest when tissue was incubated in the presence of bicarbonate ions and when 2 mg of glucose or fructose per ml was added to the incubation medium. Several other agents known to inhibit lipolysis and to decrease cyclic AMP levels in fat cells, including niacin, 5-methylpyrazole-3-carboxylic acid, and prostaglandin E1 were also effective in activating pyruvate dehydrogenase. Severe depletion of tissue ATP levels caused by the addition of oligomycin or dinitrophenol, by anaerobic incubation, or by prolonged incubation with epinephrine in the absence of albumin also activated pyruvate dehydrogenase. Incubation of adipose tissue with 1 mm oleate, 1.5 mm octanoate, 1.5 mm heptanoate, 1 mm butyrate, or 3 mm dl-β-hydroxybutyrate decreased pyruvate dehydrogenase activity 20 to 70%. The addition of 5 mm acetate, 5 mm propionate, or 3 mm 4-pentenoate led to 70 to 160% activation of pyruvate dehydrogenase, whereas 1.5 mm pentanoate had no effect. High concentrations of glucose (20 mg per ml) or of pyruvate-lactate (5 and 30 mm, respectively) also increased tissue pyruvate dehydrogenase activity.

Mechanisms of ion transport across the choroid plexus.

1. Mechanisms of ion transport across the choroidal epithelium were investigated using an in vitro preparation of the frog choroid plexus.2. Sodium was actively transported across the plexus from the vascular to the ventricular surface by an ouabain sensitive electrically silent pump. As in other epithelial membranes the rate of sodium transport was stimulated by the presence of bicarbonate ions in the Ringer solutions. Chloride and bicarbonate ions accompany the net flux of sodium across this tissue.3. Some experiments suggest that potassium is actively transported from the ventricular to the serosal surface, and that the rate of transport is a function of the extracellular potassium concentration.4. No evidence was obtained to suggest that calcium is actively transported across this tissue in either direction.5. Diamox, ethoxyzolamide, pitocin, pitressin, hydrocortisone, amiloride, spironolactone and anoxia all failed to influence sodium transport.6. The sequence of passive ion permeation across the plexus was P(Rb) approximately P(K) > P(Cs) approximately P(Na) approximately P(Cl) approximately P(HCO3) > P(Li) as deduced from diffusion potential measurements. At least for Na, K and Cl there was a good correlation between the permeability coefficients derived from unidirectional flux measurements and from electrical parameters. This indicates that exchange diffusion is unimportant as a mechanism for passive ion transport.7. The instantaneous current-voltage curves were linear in both symmetrical and asymmetrical salt solutions and the choroid plexus conductance was found to be directly proportional to the external salt concentration. These and other lines of evidence suggest that the major route of passive ion permeation across this epithelium is via the tight junction route and not through the cell interior.8. These results are discussed in relation to the in vivo studies of c.s.f. secretion and the mechanisms of active and passive ion transport across other epithelial membranes such as the gall-bladder, intestine and renal proximal tubule.

Electrophysiological studies in guard cells of tobacco

The measurement of the electrical potential of guard cells of tobacco relative to that of an external bathing solution is described. The method employs a salt bridge provided by a glass capillary inserted into an individual cell. It is shown that the intracellular potential, for example-76 mv in 11 mN KCl, is similar to that found for other cells in higher plants and appears to be independent of light intensity and the presence of bicarbonate ions. Spontaneous oscillations in the potential, with a period of 6 min, resemble those which have been observed in plant roots. Evidence that the permeability of the guard cell membrane to sodium is the same as that for potassium is discussed.

The uptake of iron by seedlings ofEucalyptus camaldulensis dehn

Higher rates of iron uptake and iron translocation inEucalyptus camaldulensis seedlings were found to occur in the presence of bicarbonate ions.

Reactivity of lime and related oxides. VI. crystal changes in carbonatated lime at different temperatures

AbstractThe ‘wet’ carbonatation of calcium hydroxide has been compared at 22° and 95° to determine the effect of temperature on the rate of formation, solubility and subsequent rate of ageing of the products, as indicated by changes in lattice structure and in surface area and average crystallite size. Direct precipitation of calcium carbonate from solution by double decomposition has been similarly compared, the conversion of the aragonitic and vateritic products to calcite being studied in solution at 95° and 22°, and in the solid state at temperatures up to 450°. Partly‐carbonatated lime has been hydrated to assess the extent to which the carbonate layer around each lime crystal inhibits further hydration.In ‘wet’ carbonatation at lower pH levels (8–12), especially in the presence of bicarbonate ions, the calcium carbonate layer developed around each lime particle ages more rapidly at the higher temperature, becoming almost non‐porous before carbonatation is complete; at higher pH levels, the carbonate is more porous, and splits off more readily. Similar ageing of calcite inhibits the conversion of aragonite to calcite. In highly alkaline media, at pH 13–14, the conversion of both aragonite and of vaterite to calcite are inhibited at 95°, but occurs readily in the solid state above 400° with considerable loss of surface area, vaterite also sintering extensively at 300°. When partly‐carbonatated lime is hydrated, the presence even of thin carbonate layers reduces the splitting of the lime particles, and the capacity of the carbonate to age afterwards partly restores their stability.