Sum Of Sodium Research Articles

Magnesium in Saline Gypsum-Containing Soils of Russia

Statistical analysis of 3802 samples of saline soils from different regions of Russia made possible to substantiate observations of a higher proportion of magnesium in soils containing gypsum compared to saline soils without gypsum. Gypsum is not a toxic salt and its presence does not lead to an increase in salinity. The increase of the salinity degree is mainly associated with sodium and magnesium salts, with the proportion of sodium more often than the proportion of magnesium. The article statistically substantiates that in the studied saline soils that do not contain gypsum, among the cations in the water extract (1 : 5), sodium most often dominates at any degree of salinity. The appearance of gypsum in the soil profile is accompanied by a significant increase in the proportion of magnesium. With a low and medium degree of salinity in horizons containing more than 1% gypsum, according to the median, as well as the arithmetic mean, upper quartile and maximum, the proportion of magnesium from the sum of sodium and magnesium in the water extract (1 : 5) is often more than 50%. Even at a strong and very strong degree of salinity, the proportion of magnesium in gypsum-containing horizons is significant and amounts to 43 and 31%, respectively, on the median, which is 5.8–6.7 times higher than the proportion of magnesium in gypsum-free horizons of the same degree of salinity.

Exhaled breath condensate as an alternative sample for drug monitoring.

Exhaled breath condensate as an alternative sample for drug monitoring.

Elevated Postmortem Vitreous Sodium and Chloride Levels Distinguish Saltwater Drowning (SWD) Deaths From Immersion Deaths Not Related to Drowning But Recovered From Saltwater (DNRD)

A 5-year prospective study of saltwater-related deaths was undertaken in 2 medico-legal centers in Australia. This demonstrated a statistically significant elevation (P<0.01) in postmortem vitreous sodium and chloride (PMVSC) levels and sum of sodium and chloride levels in 15 cases of deaths due to saltwater drowning (SWD) in comparison with 7 immersion deaths not related to drowning but recovered from saltwater (DNRD), and with 50 case controls. From our data, PMVSC was superior to using sodium or chloride levels alone in discriminating SWD from DNRD and controls. It is proposed that in cases where bodies are retrieved from a saltwater environment and SWD is suspected, a PMVSC of 284 mmol/L or higher is consistent with SWD. Conversely, a PMVSC level of less than 258 mmol/L is inconsistent with SWD. A PMVSC between 258 and 284 mmol/L is inconclusive or noninformative, and circumstantial evidence and autopsy findings are needed to determine the cause of death. It is suggested that PMVSC measurement is a worthwhile test in determining the cause of death in cases where bodies are recovered from saltwater, especially in cases where an internal examination of the body may not be authorized or where objections to autopsy are upheld.

Ion concentration homeostasis and the regulation of neuronal firing activity: the role of cation-chloride cotransporters

Ion concentration homeostasis is essential for normal neuronal functions and its changes can underlie different pathological conditions including seizures. However the mechanisms of these processes are poorly understood. Studying the dynamical and biophysical mechanisms of regulation of neuronal intra- and extra-cellular ion concentrations is important for the development of methods to treat neurological disorders. We constructed a conductance-based neuron model [1], which includes dynamic variables representing the intracellular Na+ and extracellular K+ concentrations. In this model, the Na+ and K+ concentrations are affected by sodium, potassium, and leak currents, Na+-K+ pump current, an uptake of potassium ions by glial current, and potassium diffusion. The leak current is represented by the sum of sodium, potassium and chloride leaks. The concentrations couple to the membrane voltage equations via the Nernst reversal potentials. The model also contains a voltage-gated calcium current and a simple model for the intracellular Ca2+ dynamics. The model produces slow and large-amplitude oscillations in ion concentrations similar to oscillations observable during seizures or seizure-like activity in vitro. We extended this model to include Cl- concentration dynamics. In the nervous system, the intracellular Cl- ion concentration (Cl-]i) determines the strength and polarity of GABAergic neurotransmission. This concentration is maintained by the activity of cation-chloride cotransporters (CCCs). We explored in a computational study the roles of two CCCs (the NA-K-2Cl cotransporter, NKCC1, and the K-Cl cotransporter, KCC2) in ion concentration homeostasis and in the generation of pathological oscillatory activity in neurons. Our computational studies show that reciprocal changes in the expression of NKCC1 (which elevates [Cl]i) and KCC2 (which decreases [Cl-]i) can change Cl- reversal potential (ECl) and significantly alter the effects of GABAA receptor (GABAAR) mediated inhibitory input. Under certain circumstances, this can evoke or prevent seizure-like activity, and we investigate dynamical and biophysical mechanisms of these phenomena. The model suggests that regulatory abilities of CCCs are increased with increasing GABAARs activation. Both simulated elevation of concentration of extracellular potassium ion ([K+]o,∞) and NA-K-2Cl cotransporter activity promote seizure-like activity. Our studies show that developmental regulation of expression of NKCC1 and KCC2, in conjunction with concentration dynamics, can alter Cl- electrochemical gradient and strength and polarity of GABAA neurotransmission. The computational studies corroborate that CCCs are potential targets for treatment of neurological diseases, which involve dysfunctions in intracellular ion concentration homeostasis.

Adding lactate to the prime solution during hypothermic cardiopulmonary bypass: a quantitative acid–base analysis

The effect of adding lactate to the cardiopulmonary bypass (CPB) prime was investigated using Stewart's quantitative acid-base approach. According to this quantitative model, serum pH and bicarbonate are determined by three independent factors: the partial pressure of carbon dioxide (PCO(2)), the total concentration of weak acids (e.g. albumin), and the strong ion difference. The apparent strong ion difference is calculated as the sum of sodium, potassium, magnesium and calcium minus chloride concentrations. The pH decreases with a smaller strong ion difference and vice versa. Twenty patients scheduled for coronary surgery were studied prospectively. All patients were treated identically, except for the prime, which either contained lactate or was lactate free. Just before bypass and before coming off bypass, haemoglobin, glucose, plasma osmolality and colloid osmotic pressure were determined; albumin, lactate, sodium, potassium, ionized calcium, magnesium, phosphate, arterial pH, PCO(2), bicarbonate, and base excess were measured for use in Stewart's analysis. Metabolic acidosis had resolved by the end of bypass with the lactated prime. Although the strong ion gap (apparent minus effective strong ion difference) increased significantly in both groups, its composition differed significantly between the groups. The Stewart technique detected polyanionic gelatin as a weak acid component contributing to the unidentified anion fraction. Colloid osmotic pressure was maintained in both groups. Exogenous lactate attenuates acidosis related to CPB. The oncotic and weak acid deficits produced by hypoalbuminaemia may be compensated for temporarily during CPB by polyanionic synthetic colloids such as succinylated gelatin.

Solute composition and heat shock proteins in rat renal medulla.

The high content of heat shock proteins (HSPs) 25 and 72 in the hyperosmotic inner medulla of the concentrating kidney has been ascribed to the high NaCl and urea concentrations in this kidney zone. To assess the effects of variations in the composition of solutes in the renal medulla on the intrarenal distribution of HSPs, rats were fed either a high- or low-Na diet for 3 weeks. These diets result in greatly differing urine and inner medullary solute composition. Sodium dodecyl sulphate polyacrylamide gel electrophoresis and Western blot techniques were used to analyse HSP25 and HSP72 in the cortex, outer medulla and inner medulla. In addition, the amounts of organic osmolytes (sorbitol, myo-inositol, betaine and glycerophosphorylcholine) and urea in the tissue were determined by high-performance liquid chromatography. Intra- and extracellular electrolyte concentrations at the papillary tip were measured by electron microprobe analysis. In the high-Na group, urine osmolality was about 1000 mosmol/kg lower than in rats fed a low-Na diet, due to lower urea concentrations. The sum of urine sodium and potassium concentrations, however, did not differ between the two groups. Neither in the outer nor in the inner medulla was the sum of the concentrations of organic osmolytes affected by the dietary treatment. The sum of sodium, potassium and chloride concentrations did not differ between the two experimental groups, neither in the interstitial nor in the intracellular compartments. However, the urea content and the amounts of HSP25 and HSP72 were significantly lower in the inner medulla of the group of rats fed a high-Na diet. Our results suggest that urea participates in the regulation of the medullary levels of the HSPs and that both HSP25 and HSP72 are components of mechanisms protecting medullary cells against the deleterious effects of high urea concentrations.

Effects of diabetes and insulin treatment on sorbitol and water of rat lenses.

Since increased lens sorbitol and osmotic swelling are central causative features of cataract in diabetic rats, the effects of insulin treatment on lens sorbitol, water, sodium, and potassium were studied. The sorbitol concentration in early stage diabetic lenses was greater than in normal ones by 83 mmol/kg water, and the lens water was greater by 1.3%. Sodium was greater by 9 mmol/kg water; potassium was less by the same amount so that the sum of sodium and potassium was not different. In insulin-treated diabetic lenses, the sorbitol was less than in untreated diabetic lenses by 39 mmol/kg water, and the lens water was not different. Insulin restored the potassium, but not the sodium, to normal concentration so that the sum of sodium and potassium was greater by 16 mmol/kg water. The differences in lens water were less than would be expected on the basis of osmosis due to differences in sorbitol and suggested that the lenses were able to maintain their water content within a narrow range by losing or gaining solutes to offset the differences in sorbitol.

Developmental changes in the mongrel canine brain during postnatal life

Normal values for changes in brain growth, chemical composition and morphologic features of the mongrel dog between birth and maturity were established in studies of 43 puppies between birth and 6 months of age and 3 adult dogs. Brain weight in puppies increased as the sodium, potassium and chloride contents of brain decreased between birth and 60 days; values similar to the adult were observed in puppies at 3 to 6 months of age. The concentrations of sodium and chloride decreased while the concentration of potassium increased in brain water between birth and 60 days, but the sum of sodium, potassium and chloride concentrations in brain water, an index of brain osmolality, did not change during postnatal development. Total protein (mg/g dry brain) did not change, but DNA (mg/g dry brain) decreased with age; ratios of total protein:DNA increased from birth and were maximal at 90 days. Morphologic changes in the canine brain were characterized by an extensive, densely cellular subependymal germinal zone at birth which, although diminished and focally discontinuous, was present at 30 days and had disappeared by 60 days of age. The gross appearance and histologic changes observed in the mongrel canine brain observed between 1 and 60 days of age are similar to changes described for the human brain between 28 and 40 weeks gestation. We conclude that the mongrel canine brain is a suitable model for studying mechanisms of injury to the neonatal human brain.

Effects of indomethacin on renal hemodynamics and on water and sodium excretion by the isolated dog kidney.

Blood-perfused isolated dog kidneys demonstrate steady increases in blood flow and in water and sodium excretion which could be attributed to the accumulation of renal prostaglandins in the perfusing blood. This hypothesis was tested by adding indomethacin, a potent inhibitor of prostaglandins synthesis, to the perfusing blood. Indomethacin completely prevented the vasodilation observed in control kidneys, without affecting glomerular filtration rate. Urine volume was not modified but sodium excretion was enhanced while the steady free water clearance increment observed in the control kidneys was depressed by indomethacin. The sum of sodium and free water clearances which, in the absence of antidiuretic hormone, constitutes an index of the part of the filtered load of solutes which escapes proximal tubular reabsorption, was not modified by indomethacin. Finally, indomethacin partially maintained the osmotic cortico-papillary gradient which was abolished after 2 hrs perfusion in control kidneys. These data suggest that prostaglandins accumulation in the blood is probably the major cause of the vasodilation taking place in isolated blood-perfused kidneys. This vasodilation does not account for decreased proximal reabsorption but partially explains the ADH-resistant diabetes insipidus developing in the isolated kidney. Moreover, indomethacin inhibits sodium reabsorption in the ascending limb of Henle's loop and increases water transport in the collecting duct.

Net uptake of potassium in Neurospora. Exchange for sodium and hydrogen ions.

Net uptake of potassium by low K, high Na cells of Neurospora at pH 5.8 is accompanied by net extrusion of sodium and hydrogen ions. The amount of potassium taken up by the cells is matched by the sum of sodium and hydrogen ions lost, under a variety of conditions: prolonged preincubation, partial respiratory inhibition (DNP), and lowered [K](o). All three fluxes are exponential with time and obey Michaelis kinetics as functions of [K](o). The V(max) for net potassium uptake, 22.7 mmoles/kg cell water/min, is very close to that for K/K exchange reported previously (20 mmoles/kg cell water/min). However, the apparent K(m) for net potassium uptake, 11.8 mM [K](o), is an order of magnitude larger than the value (1 mM) for K/K exchange. It is suggested that a single transport system handles both net K uptake and K/K exchange, but that the affinity of the external site for potassium is influenced by the species of ion being extruded.

Variations in muscle electrolyte composition due to sampling and to aging.

1) A difference in muscle potassium was demonstrated in samples from 2 different sites of the same animal when potassium was expressed in terms of fat free dry muscle solids. This difference did not exist when potassium was expressed in terms of its concentration in calculated intracellular water. We suggest that the discrepancy was related to differences in connective tissue or extracellular solids between the 2 samples, and that potassium expressed in terms of its concentration in intracellular water was the more meaningful expression. 2) A small but significant decrease in potassium associated with growth and aging was also noted. This difference was demonstrated expressing potassium in terms of muscle solids or intracellular water concentration. A reciprocal increase in calculated intracellular sodium was noted such that the sum of sodium and potassium remained constant.

FACTORS AFFECTING THE POTASSIUM CONTENT OF INCUBATED BRAIN SLICES

When rat cerebral cortex slices are incubated in glucose–saline medium in the presence of oxygen, the slices lose half of their potassium almost immediately and then reconcentrate it to some extent. Uptake of potassium proceeds further if glutamate is added to the medium but, since the apparent intracellular space is also increased by glutamate, the intracellular potassium concentration is not increased by glutamate. The difference between the potassium concentrations in the incubated slice and in the medium reaches a maximum when the medium contains about 5 mM potassium. In the absence of oxygen, under ordinary conditions, slices lose potassium rapidly but the final concentration reached remains higher than that of the medium and this difference is marked if the concentration in the medium is high. The greatly depleted potassium content of slices which have been incubated anaerobically can be largely restored by subsequent aerobic incubation. The rate and extent of this restoration decreases with the length of time during which the slices have been deprived of oxygen. If the medium contains pyruvate or if the slices have been subjected to a previous period of aerobiosis, anaerobic glycolysis is stimulated and concomitantly the potassium concentration in the slices increases. The effects of pyruvate and previous aerobiosis are additive. The sum of sodium and potassium in slices incubated under various conditions does not vary greatly but the sum is significantly increased in the presence of glutamate, in phosphate instead of bicarbonate-buffered medium, and, especially, in medium containing a high potassium concentration. The fluid taken up in swelling has approximately the same total cation content as that of the medium.

FACTORS AFFECTING THE POTASSIUM CONTENT OF INCUBATED BRAIN SLICES

When rat cerebral cortex slices are incubated in glucose–saline medium in the presence of oxygen, the slices lose half of their potassium almost immediately and then reconcentrate it to some extent. Uptake of potassium proceeds further if glutamate is added to the medium but, since the apparent intracellular space is also increased by glutamate, the intracellular potassium concentration is not increased by glutamate. The difference between the potassium concentrations in the incubated slice and in the medium reaches a maximum when the medium contains about 5 mM potassium. In the absence of oxygen, under ordinary conditions, slices lose potassium rapidly but the final concentration reached remains higher than that of the medium and this difference is marked if the concentration in the medium is high. The greatly depleted potassium content of slices which have been incubated anaerobically can be largely restored by subsequent aerobic incubation. The rate and extent of this restoration decreases with the length of time during which the slices have been deprived of oxygen. If the medium contains pyruvate or if the slices have been subjected to a previous period of aerobiosis, anaerobic glycolysis is stimulated and concomitantly the potassium concentration in the slices increases. The effects of pyruvate and previous aerobiosis are additive. The sum of sodium and potassium in slices incubated under various conditions does not vary greatly but the sum is significantly increased in the presence of glutamate, in phosphate instead of bicarbonate-buffered medium, and, especially, in medium containing a high potassium concentration. The fluid taken up in swelling has approximately the same total cation content as that of the medium.

A METHOD FOR THE DETERMINATION OF TOTAL BASE (SUM OF SODIUM, POTASSIUM, CALCIUM, AND MAGNESIUM) IN BLOOD

A METHOD FOR THE DETERMINATION OF TOTAL BASE (SUM OF SODIUM, POTASSIUM, CALCIUM, AND MAGNESIUM) IN BLOOD