Electrolyte Gradient Research Articles

A Sensitivity Study of Micellar/Polymer Flooding

Abstract The compositional simulator of Pope and Nelson has been extended to include a number of additional effects. The efficiency of the oil displacement has been calculated as a function of slug size, polymer drive size, surfactant and oil concentrations in the slug, slug/oil bank and drive/slug mobility ratios, surfactant and polymer absorption, interfacial tension (IFT), phase type, binodal curves, plait point location, capillary desaturation curves for each point location, capillary desaturation curves for each phase, relative permeabilities, waterflood residuals, phase, relative permeabilities, waterflood residuals, dispersion, electrolyte gradient, and amount of surfactant injected. High-concentration slugs in a Type II (+) (or plait point left) phase environment were found to be less dependent on low IFT than low-concentration slugs or slugs in a type II (-) phase environment. For the Type II (-) case, oil phase environment. For the Type II (-) case, oil recovery is not sensitive to plait point location. However, the best oil recovery for a given amount of injected surfactant occurs where a salinity higher than optimal exists downstream of the slug and a salinity lower than optimal exists upstream of the slug (in the polymer drive) and the slug itself traverses as much of the reservoir as possible in the low-tension Type III environment. The low final salinity promotes low final retention of surfactant. For the cases studied, the salinity, surfactant concentration, oil concentration, and polymer concentration of the slug itself then made relatively little difference. Introduction Several authors have examined one-dimensional simulation of surfactant flooding and the various complex compositional effects that occur during the displacement of oil with surfactants and polymers. Nelson and Pope presented laboratory results showing the importance of the Type III phase environment and how oil recovery can result from mechanisms other than low IFT. Actually, several key phenomena affecting oil recovery are strongly coupled and need to be considered simultaneously both to understand and to simulate the process. The simulator of Pope and Nelson was a first attempt to model these effects, which include IFT, phase behavior, fractional flow, adsorption, and polymer properties as a function of electrolyte. Ion exchange properties as a function of electrolyte. Ion exchange has been shown to have an important impact on the process as well, since the electrolyte environment process as well, since the electrolyte environment affects many of the most important fluid properties involved. Pope and Nelson have shown how the displacement of oil is "miscible-like" under certain conditions, even when dispersion and adsorption are considered and small slugs are used. However, to be practical, a very carefully designed electrolyte practical, a very carefully designed electrolyte gradient must exist (or some other equivalent gradient of another variable such as surfactant molecular weight, alcohol, etc.). Here we continue the investigation of these process variables by presenting results of a sensitivity study. Both presenting results of a sensitivity study. Both water and oil-rich surfactant slug cases are simulated. Model Changes Pope and Nelson presented a description of the Pope and Nelson presented a description of the original simulator. Several changes that have been made will be discussed briefly. The IFT functions are now those proposed by Healy and Reed. ....... (1) ....... (2) SPEJ P. 357

Studies on the crystalline lens. XXVII. Kinetic and bioelectric measurements of galactose cataracts in rats

The pathogenesis of galactose cataract in rat lenses was investigated by measuring changes in bioelectric potential, hydration, ion distribution and kinetics of sodium and potassium movement in cataractous lenses. During initial and vacuolar stages of cataract formation, the potential decreased in parallel with the decrease in concentration of potassium. The latter results primarily from dilution consequent to an increase in hydration. Throughout these stages, concentrations of sodium and chloride in cataractous lenses increased gradually with time on the galactose ration up to the thirteenth day. The concentration of sodium and chloride rose abruptly by the fifteenth day at which time the concentration of potassium fell abruptly. These changes were parallel to the sudden appearance of nuclear cataract and were accompanied by almost total loss of potential reflecting the disappearance of the electrolyte gradient. The rate of efflux of 86Rb (as a substitute for 42K) in cultured lenses of rats maintained on a galactose ration for 3 days was found to increase while the rate of active transport appeared to decrease compared with that of normal lenses. These findings are incompatible with the constant level of potassium found in lenses in situ. That these results might not apply to lenses in vivo because of injury associated with their removal from the globe is discussed in light of experimental evidence showing that the bioelectric potential is reduced by half following excision of the lens from the globe. However, these observations do not preclude the possibility that the rate of active transport of potassium in cataractous lenses in situ had not, in fact, increased. Further studies involving saturation kinetics of potassium transport showed that in rabbit lenses the rate of active transport increases with increasing concentration of intracellular sodium. These observations may provide a rational basis for any possible increased activity in the cation pump in sodium-rich cataractous rat lenses.

Origin of acetyl strophanthidin-induced ventricular arrhythmias.

To examine the origin of digitalis-induced ventricular tachycardia (VT), acetyl strophanthidin (AS) (25 mug/min) was perfused into a limited zone of myocardium in intact anesthetized dogs through a catheter placed fluoroscopically in the left anterior descending artery without ischemia. A second catheter in the great cardiac vein sampled venous effluent from this region. His and left bundle branch depolarizations were recorded and bipolar intramural electrograms from endocardial and epicardial sites within the anterior descending region were obtained. No conduction alterations preceded arrhythmia. Cardiac venous K+ rose from 3.3 +/- to 4.4 +/- 0.2 meq/liter (P less than 0.001), indicating egress from the perfused zone. 10 animals (Group 1) were sacrificed 2 min after onset of VT while 11 (Group 2) continued until fibrillation (4-14 min). All showed normal (endocardial leads to epicardial) transmural depolarization during sinus rhythm, but 10/21 demonstrated reversal, usually late during VT, including 8/11 in Group 2. Epicardial activation preceded fascicular activation and QRS. Recordings from the border and circumflex regions in 10 additional dogs (Group 3) demonstrated activation reversal only in the border zone. Myocardial K+ was reduced (mean 63 +/- 1 mueq/g) and Na+ increased (mean 41 +/- 2 mueq/g) in the perfused zone (nonperfused circumflex area K+ 72 +/- 1, Na+ 33 +/- 1 mueq/g, P less than 0.001 for both); changes were similar in inner and outer ventricular wall. In related experiments, subepicardial injections of AS induced activation reversal within the immediate area, similar to recordings during coronary infusion. Reversed transmural activation with early epicardial depolarization suggest VT arises within myocardium; electrolyte gradients between adjacent regions may be causative.

Electrolyte- and urea concentration profiles of the kidney in experimental asymmetric glomerulonephritis (author's transl)

Bilateral studies on kidney function concerning the electrolyte and urea concentration-profiles in renal medulla were performed in experimental unilateral acute glomerulonephritis in rabbits. 1. Both in the intact and in the glomerulonephritic kidneys sodium is concentrated mainly in the outer medulla and urea in the inner medulla. 2. In the glomerulonephritic kidneys the reduction of the filtered load seems to impair the regions of mainly passive concentrating mechanisms more than those of mainly active transport mechanisms. 3. Potassium gradients are not involved, the tissue concentrations of the glomerulonephritic kidneys however are diminished by 20 %. 4. According to the decreasing interstital electrolyte and urea gradients the osmolarity of the collecting ducts of the glomerulonephritic kidneys are diminished. These results support the conclusion, that the urinary concentrating defect in Masuginephritis is due mainly to the unability to concentrate urea.

Indomethacin inhibition of bumetanide diuresis in dogs.

Abstract: Clearance experiments in conscious, trained, intact dogs and also a one minute urine collection in conscious, ureterostomized dogs show that indomethacin pretreatment significantly alters the renal haemodynamic end excretional effects of bumetanide. The haemodynamic parameters (inulin and PAH clearance) are significantly reduced during the time interval 10–40 minutes after bumetanide administration in indomethacin pretreated dogs. In the same conditions urine volume, and sodium and chloride excretion are reduced while potassium excretion is less influenced. Indomethacin pretreatment does not affect the abolition of the cortico‐medullary electrolyte gradient caused by bumetanide administration. The results support evidence for an important role of prostaglandins in the diuretic effect of bumetanide.

Observations of the early diuretic response after intravenous administration of bumetanide and furosemide in dogs.

A transient natriuretic peak was observed in dogs the third minute after the i.v. administration of the highly active diuretics bumetanide and furosemide. The peak is dependent on the sodium balance such that it is potentiated during positive sodium balance and is not observed in sodium depleted dogs. A relationship exists between the simultaneous occurrence of the peak and abolition of the cortico-medullary electrolyte gradient.

Comparison of double layer potentials in lipid monolayers and lipid bilayer membranes

It is shown that the Gouy-Chapman double layer analysis adequately describes the variation of the surface potential of monolayers of acidic natural lipids over a wide range of surface charge density and salt concentration. It is also shown that the potential which initially appears when an electrolyte gradient is rapidly imposed across a bilayer membrane is due to a difference in the double layer potentials on the two sides of the membrane. This conclusion follows from the fact that the observed bilayer potentials arise much more rapidly than can be accounted for by charge migration across the membrane and from the observation that the bilayer membrane concentration potentials, when measured immediately after establishment of a gradient, are equal to the surface potential change observed when the subphase concentration of a monolayer of the same lipid is changed by an amount equal to the gradient across the bilayer. The bilayer potential and monolayer potential changes, so measured, agree in a number of different electrolyte solutions over a wide range of electrolyte concentrations and surface charge densities. Because of this agreement and the applicability of the Gouy theory to monolayers, initial bilayer potentials may be calculated if the composition of the mixture used to form the membrane is known, provided that the pK's and areas of such components are available. In the absence of this information, membrane potentials may be calculated from electrophoretic data on the membrane lipid mixture; the conditions under which the latter approach is possible have been determined. The experimental results indicate that the composition of monolyers and bilayers spread from the same lipid mixture in decane are very similar, that the composition of the two types of film closely resembles the composition of the solution used to generate them, and that bilayer membranes are close-packed. The evidence further indicates that if any hydrocarbon solvent remains in these bilayers, it must be so situated that it contributes little, if anything, to the surface area. The steady state potential in the bilayer membrane system is frequently not identical with the initial potential which supports the hypothesis that in many cases only a fraction of the electrical conductance of unmodified membranes is caused by the ions which constitute the bulk electrolyte. An expression for the relationship between diffusion and double layer potentials has been derived which shows that, in the absence of any intrinsic selectivity of the hydrocarbon region of the membrane for hydrogen, hydroxyl, or impurity, the two potentials should be identical.

The effect of reversal of Na + and K + electrochemical potential gradients on the active transport of amino acids in Ehrlich ascites tumor cells

1. 1. The net uptake of α-aminoisobutyric acid (AIB) in Ehrlich ascites tumor cells has been studied under a variety of transmembrane concentration gradients of Na +, K + and AIB itself. 2. 2. Before the transport measurements, the cells were prepared in such a way as to abolish or minimize exchange of extracellular AIB with endogenous amino acids, although the incubation with AIB was shown to have no significant effect on the intracellular concentrations of endogenous amino acids, as determined by an amino acid autonanalyzer. 3. 3. The results are in agreement with the ion gradient hypothesis, in that the uptake of AIB rises in proportion to the increase of the parallel electrochemical potential gradient of Na + and the antiparallel electrochemical potential gradient of K +. 4. 4. Reversal of the net AIB flux was observed only after very drastic inversion of the above-mentioned gradients, i.e. if the driving forces were on the order of — 4000 joules·mole −1 in opposition to the inward movement of AIB. 5. 5. We have concluded that an additional driving force of at least 4000 joules·mole −1 (approximately 950 cal·mole −1) must be present in addition to the electrolyte gradients. This unexplained driving force may be provided by direct coupling of amino acid transport to cellular metabolism, although alternative explanations such as an unequal distribution of alkali metal ions in the cellular space, e.g. between the nucleus and cytoplasm, cannot be completely excluded at this time. 6. 6. In the presence of 0.5 mM ouabain, the deficit in driving force is reduced to 2240 joules·mole −1, but it is not abolished.

Role of hemodynamic changes in the effect of furosemide on the renal concentrating mechanism

Renal blood flow (RBF) was measured in anesthetized dogs with a square-wave electromagnetic flowmeter. When RBF to one kidney was held constant during infusion of furosemide (20 μg/kg/min) the effect of a drug on electrolyte and water excretion appeared to the greater in the unrestricted kidney. Inasmuch as restricting blood flow reduced renal perfusion pressure, the difference in excretion between the two kidneys could not be unequivocally attributed to the difference in blood flow. A low dose of furosemide (0.1 mg/kg, i.v.) abolished the cortico-medullary electrolyte gradient within 10 min even when the increase in RBF was prevented. Apparently, an increase in RBF per se is not responsible for decreasing the concentrating ability. The abolishment of the electrolyte gradient by furosemide can be explained in terms of a change in solute concentration but not in terms of a change in solute content. The data suggest, therefore, that furosemide induces a redistribution of RBF toward the medulla. It is concluded that the increase in RBF and more importantly, the redistribution of RBF, produced by furosemide can markedly enhance the effect of the drug, particularly on the concentrating mechanism.

Measurement of Electrolyte Gradient in an Operating Fuel Cell

Reference mercury, mercuric oxide electrodes have been developed for monitoring the concentration of potassium hydroxide in hydrogen‐oxygen fuel cells operating at 27° and 70°C.

Renal medullary electrolyte and urea gradient in chickens and turkeys.

Renal medullary electrolyte and urea gradient in chickens and turkeys.

Uphill transport of urea in the dog kidney: effects of certain inhibitors.

To study the renal medullary transport and accumulation of urea in dogs independent of water transport, we obliterated the medullary electrolyte gradient by a sustained ethacrynic acid diuresis. Infusions of urea were also given at various rates to vary urinary urea concentration. In the steady state, the kidneys were removed, and slices were analyzed for water, urea, and electrolytes. In every experiment in 15 dogs over a range of urinary urea concentration from 19 to 230 mmoles per L and urine flow from 0.5 to 9.7 ml per minute per kidney, an intrarenal urea gradient persisted, and urinary urea concentration was always lower than papillary water urea concentration. The magnitude of this uphill urinary-papillary gradient (mean +/- SE = - 21 +/- 2.9 mmoles per L) was not affected by hemorrhagic hypotension or a nonprotein diet. In 12 additional experiments begun similarly, inhibitors were infused into one renal artery. Both iodoacetate, an inhibitor of anaerobic glycolysis, and acetamide, an analogue of urea, markedly and significantly reduced both the intrarenal urea gradient and the uphill urinary-papillary gradient. In contrast, cyanide, an inhibitor of oxidative metabolism, had no observable effect on the urea gradients. The data are best explained by postulating an active transport system for urea in the medullary collecting duct deriving its energy from anaerobic glycolysis.

The effects of new diuretics on net ion movements in sodium-rich smooth muscles.

The effects of furosemide, ethacrynic acid, triamterene, and an aldosterone antagonist (Su-11927) were studied on recovery of electrolyte gradients by Na-rich pieces from rabbit uteri and aortas. In sufficient concentration furosemide and ethacrynic acid appeared to inhibit Na extrusion. Only furosemide inhibited K uptake as well. A small concentration of ethacrynic acid (0.1 μg/ml) increased Na extrusion from Na-rich uterine pieces but did not increase K uptake. Thus K gain and Na extrusion were not always reciprocally related. Triamterene and Su-11927 altered recovery of electrolyte gradients, but convincing evidence for inhibition of Na active transport was not obtained. Whether inhibition of Na extrusion without inhibition of K uptake, as by ethacrynic acid, could be considered convincing evidence of inhibition of active transport was discussed.

The effect of various diuretic agents on renal electrolyte and urea concentration gradients in rats.

Die Konzentrationsgradienten von Na+und Harnstoff im Rattennierengewebe werden durch intravenose Applikation von Merallurid, Salyrgan und Hydrochlorothiazid nicht beeinflusst. Die Anderung des Na-Gradienten nach Aminophyllin hangt von der Injektionszeit ab. Acetazolamid-, Chlorothiazid- und Furosemid-Injektion fuhrt jedoch zur Senkung oder zum Verschwinden eines Na-Gradienten. Die Kaliumkonzentration in der Rinde und Papilla wird durch Hg- und Sulfonamid-Diuretica erniedrigt.

SEPARATION OF SUBCELLULAR PARTICLES BY DENSITY-GRADIENT ELECTROPHORESIS.

Abstract 1. 1. Data on the separation of mitochondrial and microsomal fractions from rat liver by density-gradient electrophoresis with and without electrolyte gradients are described. Physiological cations were deliberately excluded from the system. The theoretical basis of electrophoresis in density and electrolyte gradients is discussed. 2. 2. A mitochondrial fraction prepared in the presence of EDTA is shown to consist principally of mitochondria and other particles which are probably nuclear fragments. 3. 3. Microsomes (glucose 6-phosphatase particles) have been separated from ferritin, and by means of electrophoresis on an electrolyte gradient a complex charge distribution has been demonstrated for microsomes. Other minor components are present.

Carbohydrate metabolism and electrolyte content of rabbit diaphragm in vitro: effect of Na pyruvate.

Effects of carbohydrate intermediates on conservation of electrolyte gradients in muscle were studied by incubating segments of rabbit diaphragm in substrate-free media or media containing either 5.6 mm glucose, fructose-1, 6-diphosphate, pyruvate, or α-ketoglutarate. These were without effect on Na+-K+ gradient in glycogen-rich diaphragm. Loss of K+ and gain of Na+ were slightly greater in pyruvate- than in glucose-fortified media. Glycogen-poor diaphragm, however, lost considerably less K+ and gained less Na+ in glucose than in substrate-free media. Other substrates did not reduce decay of electrolyte gradients. Loss of K+ was 19% greater with α-ketoglutarate, 33% with fructose-1,6-diphosphate, and 51% with pyruvate than with glucose. Sodium gain was accelerated by 8%, 16%, and 49% with α-ketoglutarate, fructose-1,6-diphosphate, and pyruvate, respectively. Only pyruvate facilitated chloride accumulation in muscle. Although the ability of glucose to decelerate loss of K+ and gain of Na+ in glycogen-poor diaphragm agrees with the hypothesis that Na+-K+ transport is ATP dependent in muscle, inhibitory effects of pyruvate and fructose-1,6-diphosphate remain to be explained.