Reduction In Potassium Concentration Research Articles

Ion concentrations in cerebrospinal fluid in wakefulness, sleep and sleep deprivation in healthy humans.

Sleep is controlled by a circadian rhythmicity, via a reduction of arousal-promoting neuromodulatory activity, and by accumulation of somnogenic factors in the interstitial fluid of the brain. Recent experiments in mice suggest that a reduced neuronal excitability caused by a reduced concentration of potassium in the brain, concomitant with an increased concentration of calcium and magnesium, constitutes an important mediator of sleep. In the present study, we examined whether such changes in ion concentrations could be detected in the cerebrospinal fluid of healthy humans. Each subject underwent cerebrospinal fluid collection at three occasions in a randomized order: at 15:00 hours-17:00 hours during waking, at 06:00 hours-07:00 hours immediately following 1 night of sleep, and at 06:00 hours-07:00 hours following 1 night of sleep deprivation. When compared with wakefulness, both sleep and sleep deprivation produced the same effect of a small (0.1mm, about 3%), but robust and highly significant, reduction in potassium concentration. Calcium and magnesium concentrations were unchanged. Our results support a circadian modulation of neuronal excitability in the brain mediated via changes of the interstitial potassium concentration.

Icing treatment in rats with crush syndrome can improve survival through reduction of potassium concentration and mitochondrial function disorder effect.

Crush syndrome (CS), a serious medical condition, which is characterized by damage to myocytes due to pressure and is associated with high mortality, even when patients receive fluid therapy. Icing therapy over the affected muscle has been reported to be effective in improving mitochondrial dysfunction and inflammation. These effects are thought to be secondary to improvements in the leakage of potassium and myoglobin from the damaged myocytes in the early stages of disease. However, their effects on the various symptoms of CS are unclear. It was hypothesized that treatment with icing will inhibit the influence of potassium by vasoconstriction, exert anti-inflammatory effects in the affected myocytes and improve mitochondrial function The CS model constructed by subjecting anesthetized rats to bilateral hindlimb compression with a rubber tourniquet for 5 h. The rats were then randomly divided into six groups: i) Sham; ii) CS without treatment (CS); iii) and iv) icing for 30 or 180 min over the entire hindlimb on CS rats (CI-30 and -180), respectively; and v) and vi) local icing for 30 or 180 min over the affected area on CS rats (CLI-30 and -180), respectively. Under continuous monitoring and recording of arterial blood pressures, blood and tissue samples were collected for biochemical analyses at designated time points prior to and following reperfusion. The survival rate, vital signs, and blood gas parameters in the CS group were lethal compared with the sham group. These were also improved in the CI-30 and CLI-30 groups compared with the CS group; however, they worsened in the CI-180 and CLI-180 groups due to hypothermia. The CI-30 and CLI-30 groups demonstrated tendencies of improvements compared with the CS group. Systemic inflammation and mitochondria dysfunction had improved in these groups compared with the CS group. We suggest icing therapy to temporarily prolong the viability after crush injury. Its effectiveness can be improved by combining it with other infusion therapies.

Reduction in potassium concentration of stored red blood cell units using a resin filter

Hyperkalemia is a serious complication of rapid and massive blood transfusion due to high plasma potassium (K) in stored red blood cell (RBC) units. A potassium adsorption filter (PAF) was developed in Japan to remove K by exchanging with sodium (Na). We performed an in vitro evaluation of its efficacy and feasibility of use. Three AS-3 RBC units were filtered by each PAF using gravity; 10 PAFs were tested. Blood group, age, flow rate, and irradiation status were recorded. Total volume, K, Na, Cl, Mg, total Ca (tCa), RBC count, hemoglobin (Hb), hematocrit (Hct), and plasma Hb were measured before and after filtering each unit. Ionized Ca (iCa), pH, and glucose were measured for some units. After filtration, the mean decrease in K was 97.5% in the first RBC unit, 91.2% in the second unit, and 64.4% in the third unit. The mean increases in Na, Mg, and tCa were 33.0, 151.4, and 116.1%, respectively. iCa and pH remained low; glucose was unchanged. RBC count, Hb, and Hct decreased slightly after filtration of first units; plasma Hb was unchanged. After filtration, there was no visual evidence of increased hemolysis or clot formation. The PAF decreased K concentration in stored AS-3 RBC units to minimal levels in the first and second RBC units. Optimally, one filter could be used for 2 RBC units. Although Na increased, the level may not be clinically significant. PAF may be useful for at-risk patients receiving older units or blood that has been stored after gamma irradiation.

Potassium Depletion and Diastolic Dysfunction

Changes in extracellular potassium concentration affect nearly all aspects of myocardial function. Reductions in potassium concentration alter the resting membrane potential, membrane conductance for sodium and potassium, repolarization time, relative refractory time, and conduction velocity. The arrhythmogenic consequences of these effects of potassium depletion are well recognized by the medical community. However, the potential influence of hypokalemia on mechanical function of the heart has not been as thoroughly appreciated. More than 10 years ago, Fitzovich et al1,2 analyzed changes in left ventricular mechanical function of dogs who were either potassium replete or moderately depleted as a result of 7 days of low-potassium intake together with a high-sodium intake and thiazide diuretics. The depleted dogs had a mean plasma potassium concentration of 3.2 mmol/L. The investigators observed in the depleted dogs significant impairment of both systolic and diastolic function, with the most striking effect noted in peak rate of ventricular filling, reduced by &49% during acute elevation of preload. The same group extended the study to normal volunteers age 22 to 30 years whose cardiac mechanical function was studied noninvasively by echo and Doppler techniques.2,3 Compared with the potassium replete state, during potassium depletion (plasma potassium reduced by 1.0 mmol/L), the peak rate of ventricular filling was …

Impact of wet deposited nickel on the cation content of a mat-forming lichen Cladina stellaris

The impact of experimentally sprayed aqueous nickel solution on the concentrations of potassium, calcium, magnesium and nickel in three horizontal strata (top, 0–20 mm; middle, 20–40 mm; and base, 40–60 mm) of the cushion-forming lichen Cladina stellaris was investigated. The experimental nickel deposition range used corresponded with that from the pristine forests of the Finnish border to polluted industrial sites of Russian Kola Peninsula (0–1000 mg Ni 2+ m −2 year −1). The lichen mat retained ca. 31–66% of the nickel deposited during two growing seasons and the relative retention efficiency was highest at the low deposition end. The concentrations of cations in lichen thalli were significantly reduced only after the highest nickel deposition. Furthermore, the separate horizontal strata responded differently to nickel exposure indicating that the cation exchange sites of the top stratum were not completely saturated by nickel even after the most severe treatment. However, nickel deposited in high doses caused considerable reduction in potassium concentration indicating damage to cell membranes. Episodically deposited high concentrations of nickel can probably affect membrane integrity before detectable changes in total concentrations of cations in the lichen thallus take place. Thus, ratios of total concentrations of cations in the lichen thallus are fairly insensitive to nickel deposition, which reduces the risk of compounding effects when the ratios are used to indicate long-term acid deposition in areas with multiple pollution problems such as Kola Peninsula.

Relationship of nutrients in water with biomass and nutrient accumulation of submerged macrophytes of a tropical wetland.

The paper describes monthly biomass, seasonal and annual net primary productivity and monthly and seasonal nutrient content of four submerged macrophytes in a lentic wetland situated in the campus of Banaras Hindu University. The seasonal variation of six nutrients (NO3 -N, PO4 -P, K, Ca, Mg, Na) in water is described and their mean concentrations used in multiple regression equations to examine the relationship between nutrients in water, plant biomass and nutrient accumulation in plant body. Hydrilla verticillata (L.f.) Royle, Potamogeton crispus L., P. pectinatus L. and Aponogeton natans (L.) Engle and Krause are the constituent species. Plants show rapid growth in post-monsoon and pre-winter months. All the four species showed biomass accumulation in the rainy season. The highest rate of production in the submerged zone was 0.73 g m-2 d-1 and the minimum was 0.29 g m-2 d-1 . Maximum annual production of any species was 69 g m-2 in P. pectinatus. In all the four species the nutrient concentration decreased in the following order: calcium > nitrogen > potassium > magnesium > sodium > phosphorus. Seasonal variation of nutrient content was dependent on the period of germination, growth and development of the species. Nitrogen, phosphorus and potassium were higher in the season of growth of particular species and calcium was higher when plants matured. There was no definite trend for sodium, though magnesium varied with species. Uptake and accumulation of nutrients in submerged plants largely depend upon nutrient concentration of water, except nitrogen which was also dependent on biomas change. Sources of nutrient for plants are both sediment and water. Translocation of potassium from the overlying water to the mud by Hydrilla plants is possible as there is reduction in potassium concentration of water around Hydrilla.

Contractile properties of frog twitch fibres after D600 paralysis.

Twitch and contracture tensions were measured in single intact fibres of semitendinosus muscles with a sensitive miniature transducer. After a fibre was paralysed by a conditioning depolarization in the presence of 30 microM D600 at low temperature (around 5 degrees C), no twitch tension could be detected. When a paralysed fibre was warmed, its ability to give potassium-contractures recovered almost completely but its twitch tension revived to a variable extent, ranging from fully to partially or not at all. This variable recovery of twitch tension appeared to correlate very well with the variable repriming of Q gamma observed previously in revived fibres. The optimal temperature at which twitch tension could be revived readily lay within a narrow window roughly between 8 to 16 degrees C, within which the rate and extent of revival of twitch tension were temperature-dependent. Removal of D600 from the bathing solution after conditioning depolarization facilitated the revival of twitch tension but was neither a necessary nor a sufficient condition for revival. A reduction of potassium concentration in the high K solution or an abbreviation of the duration of conditioning depolarization could bring a fibre to a partially paralysed state (or equivocally a partially revived state) without going through complete paralysis. The paralysing actions of submaximal condition depolarizations were additive. The partially revived state was unstable and affected by repetitive stimulations in a use-dependent manner. The effect of a 0.1 Hz train of action potentials on twitch tension was generally biphasic, with a small initial suppression followed by an enhancement. It is speculated that this use-dependent enhancement could be due to a competition between D600 molecules and intracellular Ca2+ ions.

Effect of salinity level on uptake and distribution of chloride, sodium and potassium ions in citrus plants

Seedlings of the Citrus rootstocks Rangpur lime (Citrus reticulata var. austera hybrid?), Kharna khatta (C. karna Raf.) and Etrog citron (C. medica L.), were grown in a porous medium under glasshouse conditions and irrigated with 0, 25, 50 or 100 mM NaCl for 6 weeks. Chloride concentrations in roots of all three rootstocks were increased by salt treatment. Increasing the level of salinity from 25 to 100 mM NaCl did not increase further the chloride concentrations in roots of any rootstock, implying an upper limit to the extent of chloride loading in roots. The upper limit appeared to be similar for all rootstocks. Differences between the rootstocks were found in chloride concentrations in leaves and to a lesser extent in stems, emphasizing pronounced rootstock differences in root to shoot transport of chloride, i.e. in their ability for chloride exclusion. This ability increased in the order: Etrog citron, Kharna khatta, and Rangpur lime. Root, stem and leaf sodium concentrations increased with salt treatment, but a concurrent reduction in potassium concentrations with salt treatment occurred only in roots and stems. Shoot growth of Etrog citron and Kharna khatta plants was reduced significantly by 50 mM NaCl, but growth of Rangpur lime plants showed a marked reduction only at 100 mM NaCl. Shoot-growth and salt-induced changes in the concentrations of chloride, sodium and potassium in leaves and roots of each rootstock were unaffected by sodium to calcium ratios in the range 6.25 : 1 to 25 : 1 for plants treated with 50 mM NaCl, and in the range 12.5 : 1 to 50 : 1 for plants treated with 100 mM NaCl. Shoot growth and ion uptake patterns

The relationship between stimulation-induced potassium release and amylase secretion in the mouse parotid

1. The output of amylase from superfused mouse parotid segments in response to stimulation with acetylcholine (ACh), phenylephrine and isoprenaline during exposure to solutions with varying potassium concentrations was monitored by an on line automated fluorometric method. 2. During stimulation with ACh or phenylephrine a 10-fold increase in superfusion fluid potassium concentration caused an immediate very marked reduction in amylase output which was fully reversible. A 10-fold reduction in potassium concentration resulted in a prominent rise in amylase output. During stimulation with isoprenaline there was no effect on the amylase output of varying the extracellular potassium concentration. Acetylcholine and phenylephrine caused potassium release from the mouse parotid whereas isoprenaline had no such effect. 3. It appears that under conditions where stimulation-induced potassium release is enhanced there is also an enhanced amylase secretion and vice cersa. There may therefore be a link between passive potassium transport and amylase secretion.

SEASONAL VARIATIONS OF SODIUM AND POTASSIUM CONCENTRATIONS IN DIFFERENT PARTS OF THE FROG MYOCARDIUM.

Sodium and potassium concentrations in different parts of the frog heart (sinus venosus, atrium and ventricle) were investigated at various seasons of the year. The sodium concentration showed a marked periodicity in all three parts of the heart: minimum in winter, maximum in summer. Potassium concentration showed no seasonal variations, except for reduction in potassium concentration of the ventricle in the second half of the year. The experimental results for sodium can be fitted by a sine curve, the differences between minimum (in winter) and maximum (in summer) representing 46.4% (for sinus venosus), 30.4% (atrium) and 34.0% (ventricle) of the spring-autumn values. Variation in the electrolyte concentration could be explained by changes in salt. and water metabolism induced by fluctuations in the temperature on one hand, and by the removal of the animals from their natural environment on the other.

Mode of action of acetazolamide on pancreatic exocrine secretion.

In unanesthetized dogs with chronic gastric and pancreatic fistulas, an intravenous infusion of acetazolamide (Diamox), superimposed on a steady-state infusion of secretin, caused a prompt reduction in the volume and bicarbonate concentration of pancreatic secretion and a delayed reduction in potassium concentration. These changes were not caused by alterations in serum electrolytes or by the development of a metabolic acidosis. The reductions in volume and bicarbonate concentration were too rapid and extensive to be accounted for by compensatory respiratory mechanisms, and hence reflect a direct effect of acetazolamide on pancreatic secretion. Reductions in bicarbonate concentration during the infusion of acetazolamide appeared to bear a physiologic relationship to the induced slower flow rates.

A comparison of the inhibition by cardiac glycosides of the isolated intestine from the rat and the guinea pig.

A method described by Bieltvedt & Briseid (1966) and Bieltvedt (1967) for the determination of the inhibition by cardiac glycosides of the isolated, histamine‐stimulated guinea pig ileum was modified to estimate the inhibition of the acetylcholine‐stimulated rat jejunum. The glycoside concentrations causing 50 % inhibition of submaximal, isotonic contractions were determined, and the procedure was based on 20‐minute contact periods between the muscle preparations and the cardioactive substances, and then 22‐minute equilibration periods with chemical stimulation. The degree of inhibition was found to depend on the potassium content of the Tyrode solutions used. In a low potassium Tyrode solution (1.8 mM) the inhibition of the rat intestine by cardiac glycosides was found to be of the same order of magnitude as the inhibition of the guinea pig intestine. When the potassium chloride concentration was increased to 2.7 mM, the well known species difference was observed, the concentration of cardiac glycoside required for inhibition of the rat intestine being about 30 times higher than that required for inhibition of the guinea pig intestine. The range of potency of the different cardiac glycosides and aglycones which were tested in the low potassium. Tyrode solution, was the same for the two species. Presupposing an inhibition of Na+, K+‐activated transport ATPases as the basic mechanism for the inhibition by cardiac glycosides of the isolated intestine preparations, a theory of qualitative differences between the transport enzymes in the two species is advanced. In the rat intestine the presence is suggested of one ATPase which is rather resistant to inhibition by cardiac glycosides, but sensitive to a reduction in potassium concentration, in addition to a glycoside‐susceptible ATPase also present in the guinea pig intestine.

An inherited glutathione deficiency and a concomitant reduction in potassium concentration in sheep red cells.

Se medió glutation reducido (GSH) en glóbulos rojos de 427 ovejas pertenecientes a 6 razas diferentes. 25% de las ovejas de raza «Finnish Landrace» dieron un contenido de GSH de un tercio del valor obtenido en el resto. Datos familiares indican que esta deficiencia es heredada como un factor autosómico recesivo. En las ovejas que tienen esta deficiencia, la concentracion media de potasio en glóbulos rojos fué significativamente menor que la observada en las ovejas con niveles normales de GSH.

Order–Disorder Transformation in Potassium Graphite

DURING an X-ray diffraction investigation of the potassium graphites1, we concluded that the reduction in potassium concentration within the intercalate layer, which occurs on passing from stage 1 (C8K) to stage n (C12nK), is accompanied by a loss of long range order within the layer. A study of the stage 2 compound has now shown that this disordered intercalate structure (form I) transforms reversibly to an ordered state (form II) at a temperature of about −175°C.

Mechanism anti-hypertensive action of thiazides.

SummaryThe non-diuretic thiazide, diazoxide, lowers blood pressure of renal hypertensive rats in association with a decrease in aorta wall potassium content. At the same time, sodium and water concentration and their distribution in the tissue compartments of the aortas of such rats remain unchanged. It is suggested that the anti-hypertensive effect of thiazides is mediated through the reduction in potassium concentration of arterial smooth muscle.

Some factors influencing the plateau-formation in Co-treated or Nitreated single myelinated nerve fibres.

In Co-treated or Ni-treated myelinated nerve fibres, the effect of various agents on the plateau of the action current was investigated.1. Lithium could effect as a substitute for sodium in these fibres, too. Complete replacement of sodium with lithium produced reversibly an increase in the rheobase and only a slight curtailment of the plateau.2. By replacement of NaCl with choline chloride, the plateau duration was curtailed. Spike height was reduced proportionally with the reduction in sodium concentration, while the curtailment of plateau duration was saturated under higher concentrated choline.3. By replacement of NaCl with sucrose, both the spike height and the plateau duration were diminished linearly with proportion to the logarithm of sodium concentration. The plateau duration was more sensitive to changes in sodium concentration than the spike height.4. Co or Ni ion counteracted the depolarizing action of potassium ion. High concentrated potassium prolonged the plateau duration without the depolarization. On the contrary, when it depolarized the nodal membrane, the plateau duration was curtailed. The reduction of potassium concentration did not cause any appreciable change in the plateau duration.5. The deficiency of calcium ion in the surrounding media produced decrease in the rheobase, reduction in the spike height and prolongation of the plateau duration. Co or Ni ion augmented the spike height diminished by Ca-deficiency and increased the lowered rheobase. The increase in Ca concentration curtailed the plateau duration.6. Narcotics, such as urethane or cocaine curtailed the plateau duration. As Co or Ni ion counteract the reducing effect of narcotics on the spike height, the curtailment sometimes occurred without appreciable change in the spike height under the action of their suitable concentrations.7. Catelectrotonus curtailed the plateau duration, increasing its slope. On the other hand, under anelectrotonus its slope became slower, but its duration was not changed.8. Brief inward current applied during the plateau abolished the portion of the action potential following the application at a certain strength in all-ornone manner. The threshold intensity depended mainly upon the relative position of the pulse on the action potential. Much stronger pulses were needed in the early stage of the plateau than in its later stage.9. During the relative refractory period, the spike height recovered as rapidly as in the normal fibre. However, the plateau duration did not completely recover until the end of the supernormal phase which became apparent after application of these metal ions.10. Some characters of the excitation mechanism of the nodal membrane were discussed briefly.This work was aided partly by grants from the Ministry of Education of Japan.