The effects of monovalent cations Li+, Na+, K+, NH4+, Rb+ and Cs+ on the solid and solution structures of the nucleic acid components. Metal ion binding and sugar conformation.

The interactions of the monovalent ions Li+, Na+, K+, NH4+, Rb+ and Cs+ with adenosine-5'-monophosphoric acid (H2-AMP), guanosine-5'-monophosphoric acid (H2-GMP) and deoxyguanosine-5'-monophosphoric acid (H2-dGMP) were investigated in aqueous solution at physiological pH. The crystalline salts M2-nucleotide.nH2O, where M = Li+, Na+, K+ NH4+, Rb+ and Cs+, nucleotide = AMP, GMP and dGMP anions and n = 2-4 were isolated and characterized by Fourier Transform infrared (FTIR) and 1H-NMR spectroscopy. Spectroscopic evidence showed that these ions are in the form of M(H2O)n+ with no direct metal-nucleotide interaction, in aqueous solution. In the solid state, Li+ ions bind to the base N-7 site and the phosphate group (inner-sphere), while the NH4+ cations are in the vicinity of the N-7 position and the phosphate group, through hydrogen bonding systems. The Na-nucleotides and K-nucleotides are structurally similar. The Na+ ions bind to the phosphate group of the AMP through metal hydration shell (outer-sphere), whereas in the Na2-GMP, the hydrated metal ions bind to the base N-7 or the ribose hydroxyl groups (inner-sphere). The Na2-dGMP contains hydrated metal-carbonyl and metal-phosphate bindings (inner-sphere). The Rb+ and Cs+ ions are directly bonded to the phosphate groups and indirectly to the base moieties (via H2O). The ribose moiety shows C2'-endo/anti conformation for the free AMP acid and its alkali metal ion salts. In the free GMP acid, the ribose ring exhibits C3'-endo/anti conformer, while a C2'-endo/anti sugar pucker was found in the Na2-GMP and K2-GMP salts and a C3'-endo/anti conformation for the Li+, NH4+, Rb+ and Cs+ salts. The deoxyribose has C3'-endo/anti conformation in the free dGMP acid and O4'-endo/anti in the Na2-dGMP, K2-dGMP and a C3'-endo/anti for the Li+, NH4+, Rb+ and Cs+ salts. An equilibrium mixture of the C2'-endo/anti and C3'-endo/anti sugar puckers was found for these metal-nucleotide salts in aqueous solution.     

The modifications of the final stages of the complement reaction by alkali metal cations.

We studied the effects of alkali metal cations on the terminal stages of complement lysis of human and sheep HK erythrocytes. Sensitized erythrocytes (EA) were reacted with limited amounts of complement for 1 hr at 37 degrees C in buffer containing 147 mM NaCl (Na buffer), which resulted in 10-40% lysis. The unlysed cells were washed with Na buffer at 0-2 degrees C and incubated for 1 hr at 37 degrees C in buffers containing 147 mM of the various alkali metal cations. Although additional lysis (25 to 65%) occurred with K, Rb, or Cs buffer, only minor degrees developed with Na or Li buffer, only minor degrees developed with Na or Li buffer. Intermediate levels occurred with 100 mM of the divalent alkali cations. Halogen ions and SCN-(147 MM), Ca++ (0.15mM), and Mg++ (0.5 mM) did not alter the effect of the alkali metal cations. Lysis occurring in K+, Rb+ or Cs+ proceeded without lag, was temperature dependent with an optimum of 43 degrees C, and had a pH optimum of 6.5. Lysis in K and Na buffers was unaffected by 10(-3) to 10(-5) M ouabain. Experiments with mixtures of cations indicated that Na+ had a mild inhibitory effect that could be totally overcome by K+, partially by Rb+, and not at all by Cs+. Li+ had a strong inhibitory effect, 6 X 10(-5) M causing 50% inhibition in buffers containing 147 mM K+, Rb+, or Cs+. By using intermediate complexes of EA and purified complement components we demonstrated that K+ enhances the lytic action of C8 on EAC1-7 as well as that of C9 on EAC1-8. It was known that Li+ facilitates lysis when acting on the entire complement reaction. We found that Li+ enhanced the lytic action of C8 on EAC1-7, with a kinetic that differed from that of the K+ effect. In addition, Li+ inhibited the enhancing effect of K+ upon lysis of EAC1-8 by C9. This occurred at concentration of Li+ similar to those which inhibited the additional lysis by K+, Rb+, and Cs+ of cells that were pretreated in Na buffer with the entire complement sequence. We propose that the major effects of alkali metal cations on complement lysis are due to their interaction with C8 and/or membrane constitutes.     

Induction of ion transport in rat heart mitochondria by fluorescamine

This report describes experimental results which show that the fluorescent reagent fluorescamine induces mitochondrial energy-independent swelling when the incubation media contain the chloride salts of the cations Li+, Na+, K+, Rb+, and Cs+. The reaction depends on the concentration of the dye and is inhibited by Mg2+, and its extension is closely related to the amount of the primary amino groups titrated by fluorescamine. Analysis of the labeled inner membrane in polyacrylamide gel shows that the amount of aminofluorescamine complex is lower when mitochondria are in the presence of Mg2+.     

Complex Interplay between Absorber Composition and Alkali Doping in High‐Efficiency Kesterite Solar Cells

Sodium treatment of kesterite layers is a widely used and efficient method to boost solar cell efficiency. However, first experiments employing other alkali elements cause confusion as reported results contradict each other. In this comprehensive investigation, the effects of absorber composition, alkali element, and concentration on optoelectronic properties and device performance are investigated. Experimental results show that in the row Li–Na–K–Rb–Cs the nominal Sn content should be reduced by more than 20% (relative) to achieve the highest conversion efficiency. The alkali concentration resulting in highest device efficiencies is lower by an order of magnitude for the heavy alkali elements (Rb, Cs) compared to the lighter ones (Li, Na, K). Utilization of a wide range of characterization techniques helps to unveil the complex interplay between absorber composition and alkali doping. A ranking of alkali for best device performances, when employing alkali treatment, resulted in the order of Li > Na > K > Rb > Cs based on the statistics of more than 700 individual cells. Finally, a champion device with 11.5% efficiency (12.3% active area) is achieved using a high Li concentration with an optimized Sn content.     

Selectivity of alkali cation influx across the plasma membrane of oat roots: cation specificity of the plasma membrane ATPase

Influx of alkali cations (Li(+), Na(+), K(+), Rb(+), Cs(+)) across plasma membranes of cells of excised roots of Avena sativa cv. Goodfield was selective, but different, in the absence and in the presence of 1 mm CaSO(4). Ca(2+) reduced the influx rates of all of the alkali cations-especially Na(+) and Li(+). Transport selectivity changed as the external concentrations of the alkali cations increased.Plasma membrane ATPase, purified from Avena sativa roots, was differentially stimulated by alkali cations. This specificity, however, was not altered by Ca(2+) or the external cation concentrations. A close correspondence existed between the relative influx rates of K(+), Rb(+), and Cs(+) and the relative stimulation of the ATPase by these cations. A similar correspondence did not occur for Na(+) and Li(+).Selective cation transport in oat roots could result, in part, from the specificity of the plasma membrane ATPase, but other factors such as specific carriers or porters or differential diffusion rates must also be involved.     

Diffusion of Salts across a Butanol-Water Interface

Diffusion of the chloride salts of Li, Na, K, Rb, and Cs from water into 1-butanol and from 1-butanol into water was examined at temperatures from 13-40 degrees C. Distribution coefficients, interfacial transfer coefficients, Arrhenius activation energy, free energy of activation, enthalpy, and entropy of activation were determined for the diffusion of these salts across the alcohol-water interface. The results indicate that the entropy decrease made the major contribution to the change in the free energy of activation.     

Symmetry and asymmetry of permeation through toxin-modified Na+ channels.

Single Na+ channels from rat skeletal muscle were inserted into planar lipid bilayers in the presence of either 200 nM batrachotoxin (BTX) or 50 microM veratridine (VT). These toxins, in addition to their ability to shift inactivation of voltage-gated Na+ channels, may be used as probes of ion conduction in these channels. Channels modified by either of the toxins have qualitatively similar selectivity for the alkali cations (Na+ approximately Li+ greater than K+ greater than Rb+ greater than Cs+). Biionic reversal potentials, for example, were concentration independent for all ions studied. Na+/K+ and Na+/Rb+ reversal potentials, however, were dependent on the orientation of the ionic species with respect to the intra- or extracellular face of the channel, whereas Na+/Li+ biionic reversal potentials were not orientation dependent. A simple, four-barrier, three-well, single-ion occupancy model was used to generate current-voltage relationships similar to those observed in symmetrical solutions of Na, K, or Li ions. The barrier profiles for Na and Li ions were symmetric, whereas that for K ions was asymmetric. This suggests the barrier to ion permeation for K ions may be different than that for Na and Li ions. With this model, these hypothetical energy barrier profiles could predict the orientation-dependent reversal potentials observed for Na+/K+ and Na+/Rb+. The energy barrier profiles, however, were not capable of describing biionic Na/Li ion permeation. Together these results support the hypothesis that Na ions have a different rate determining step for ion permeation than that of K and Rb ions.     

Cationic selectivity and competition at the sodium entry site in frog skin

The cation selectivity of the Na entry mechanism located in the outer membrane of the bullfrog (Rana catesbeiana) skin epithelium was studied. This selectivity was determined by measuring the short-circuit current when all of the external sodium was replaced by another cation and, also, by noting the relative degree of inhibition that the alkali metal cations produced on Na influx. The ability of the Group Ia cations to permeate the apical membrane was determined from the tracer uptake experiments. The results demonstrate that (a) only Li and Na are actively transported through the epithelium; (b) the alkali cations K, Rb, and Cs do not enter the epithelium through the apical border and, therefore, Na and Li are the only alkali cations translocated through this membrane; (c) these impermeable cations are competitive inhibitors of Na entry; (d) the cations NH4 and Tl exhibit more complex behavior but, under well-defined conditions, also inhibit Na entry; and (e) the selectivity of the cation binding site is in the sequence Li congruent to Na > Tl > NH4 congruent to K > Rb > Cs, which corresponds to a high field strength site with tetrahedral symmetry.     

Fractionation of alkali metal cations in cationization of phthalic acid. A fast atom bombardment study

Competition for solvent glycerol and solute phthalic acid by the alkali metal cations Li+, Na+, K+, Rb+ and Cs+ in cationization fast atom bombardment spectra is quantitated.     

Penetration, Retention and Transport of Foliar Applied Single Salts of Na, K, Rb and Cs

The penetration, retention and transport of foliar applied chloride salts of Na-22, K-43, Rb-86, and Cs-134 were studied under controlled environmental conditions. Penetration although occurring at different rates was found to be non-selective and appears to be a passive free diffusion process. Retention in the treated area is similar for Na, K and Rb and greater for Cs. Transport of these elements away from that area and in the plant was greatest and fastest for Na and Rb and slower for Cs and K. Distribution in the plants following leaf treatment was similar for K, Rb and Cs but no significant upward transport was noted for Na. Losses from roots were greatest for Na. No significant K could be detected in the culture medium 4 days after treatment of the leaves.     

The permeability of the sodium channel in Myxicola to the alkali cations

Relative permeabilities to the alkali cations were determined, from the reversal potential (VRev), for the Na channel of internally perfused voltage-clamped Myxicola giant axons. PLi/PNa and PK/PNa are 0.94 and 0.076, respectively. Rb and Cs are not measurably permeant. VRev vs. the internal Na activity was well described by the constant field equation over a 300-fold range of internal Na concentrations. In agreement with findings on squid axons, the PK/PNa was found to increase when the K content of the internal perfusate was reduced (equivalent per equivalent substitution with TMA). Internal Rb and Cs also decreased the PK/PNa. The order of effectiveness of internal K, Rb, and Cs in increasing the Na selectivity of the Na channel was Cs greater than Rb greater than or equal to K. External Li increases the PK/PNa but this may be due to the formation of LiF internally. It may be that substances do not have to traverse the channel in order to affect the selectivity filter. Evidence is presented which suggests that the selectivity of the Na channel may be higher for Na in intact as compared to perfused giant axons. It was concluded that the channel selectivity properities do not reflect only some fixed structural features of the channel, but the selectivity filter has a labile organization.     

Ion specificity of cardiac sarcolemmal Na+/H+ antiporter

In bovine cardiac sarcolemmal vesicles, an outward H+ gradient stimulated the initial rate of amiloride-sensitive uptake of 22Na+, 42K+, or 86Rb+. Release of H+ from the vesicles was stimulated by extravesicular Na+, K+, Rb+, or Li+ but not by choline or N-methylglucamine. Uptakes of Na+ and Rb+ were half-saturated at 3 mM Na+ and 3 mM Rb+, but the maximal velocity of Na+ uptake was 1.5 times that of Rb+ uptake. Na+ uptake was inhibited by extravesicular K+, Rb+, or Li+, and Rb+ uptake was inhibited by extravesicular Na+ or Li+. Amiloride-sensitive uptake of Na+ or Rb+ increased with increase in extravesicular pH and decrease in intravesicular pH. In the absence of pH gradient, there were stimulations of Na+ uptake by intravesicular Na+ and K+ and of Rb+ uptake by intravesicular Rb+ and Na+. Similarly, there were trans stimulations of Na+ and Rb+ efflux by extravesicular alkali cations. The data suggest the existence of a nonselective antiporter catalyzing either alkali cation/H+ exchange or alkali cation/alkali cation exchange. Since increasing Na+ caused complete inhibition of Rb+/H+ exchange, but saturating K+ caused partial inhibitions of Na+/H+ exchange and Na+/Na+ exchange, the presence of a Na(+)-selective antiporter is also indicated. Although both antiporters may be involved in pH homeostasis, a role of the nonselective antiporter may be in the control of Na+/K+ exchange across the cardiac sarcolemma.     

Permeation of internal and external monovalent cations through the catfish cone photoreceptor cGMP-gated channel

The permeation of monovalent cations through the cGMP-gated channel of catfish cone outer segments was examined by measuring permeability and conductance ratios under biionic conditions. For monovalent cations presented on the cytoplasmic side of the channel, the permeability ratios with respect to extracellular Na followed the sequence NH4 > K > Li > Rb = Na > Cs while the conductance ratios at +50 mV followed the sequence Na approximately NH4 > K > Rb > Li = Cs. These patterns are broadly similar to the amphibian rod channel. The symmetry of the channel was tested by presenting the test ion on the extracellular side and using Na as the common reference ion on the cytoplasmic side. Under these biionic conditions, the permeability ratios with respect to Na at the intracellular side followed the sequence NH4 > Li > K > Na > Rb > Cs while the conductance ratios at +50 mV followed the sequence NH4 > K approximately Na > Rb > Li > Cs. Thus, the channel is asymmetric with respect to external and internal cations. Under symmetrical 120 mM ionic conditions, the single-channel conductance at +50 mV ranged from 58 pS in NH4 to 15 pS for Cs and was in the order NH4 > Na > K > Rb > Cs. Unexpectedly, the single-channel current-voltage relation showed sufficient outward rectification to account for the rectification observed in multichannel patches without invoking voltage dependence in gating. The concentration dependence of the reversal potential for K showed that chloride was impermeant. Anomalous mole fraction behavior was not observed, nor, over a limited concentration range, were multiple dissociation constants. An Eyring rate theory model with a single binding site was sufficient to explain these observations.     

The equivalent conductivity of aqueous solutions of alkali metal salts of a number of ionic polysaccharides

Measurements of the equivalent conductivity of aqueous solutions of alkalimetal salts of a number of ionic polysaccharides at 25 degrees C are reported. The polysaccharides studied are: (1) three carboxymethylcelluloses of various degrees of substitution (Li+, Na+, Cs+ salts) in the concentration range 4 X 10(-4) - 6 X 10(-2) equivalents alkali ion per liter, (2) Polypectate (Li+, Na+, K+, Cs+ salts) in the range 1.5 X 10(-4) - 2 X 10(-2) equivalent alkali ion per liter, and (3) Dextransulfate (Li+, Na+, K+ salts) in the range 3 X 10(-4) - 10(-1) equivalent alkali ion per liter. The results are compared to some earlier data and to a limiting law for conductance of rod-like polyions derived by Manning. It is concluded that although qualitative agreement is obtained between observed data and the limiting law when various polyions of different charge densities are compared at a given concentration, the concentration dependence predicted by the limiting law is in agreement with the observed curves only for polyions of a relatively low charge density. At higher charge densities appreciable deviations occur, and dextransulfate which does not have the rod-like polyion structure required by theory does not conform to the predicted concentration dependence at all.     

Monovalent ion effects on acetylcholine receptor from Torpedo californica

The effects of the five Group I monovalent ions, Li, Na, K, Rb, and Cs, on [³H]acetylcholine binding to Triton X-100 solubilized acetylcholine receptor from Torpedo californica electroplax were examined. Acetylcholine binding was not greatly affected by Li or Na, but was inhibited by the other ions in the order Cs > Rb > K. The inhibition by K appeared to occur by a mechanism identical to that for d-tubocurarine inhibition of acetylcholine binding.     

Effects of alkali cations on the nuclear magnetic resonance intensity of 23Na in rat liver homogenate.

Effects of alkali cations on the nuclear magnetic resonance intensity of 23Na were studied in rat liver homogenate. The loss in the resonance intensity of 23Na in the homogenate was able to be divided into two components, one of which is abolished by the addition of Cs+ ("Cs-sensitive component"), the other being insensitive to Cs+ ("Cs-insensitive component"). Both components were sensitive to guanidinium ion. In a pH range of 7.4-4.9, the Cs-sensitive component varied remarkably, but the Cs-insensitive component remained virtually unchanged. The sequence of effectiveness of alkali cations (300 mmol/kg sample) in restoring the fractional intensity of 23Na was: Cs approximately Na greater than Li approximately Rb greater than K. It was suggested that the sequences of effectiveness of alkali cations in abolishing the two components are quite different from each other. The present results were examined within the framework of a simple model. Within this framework, the results suggest that there occur, in particulate fractions, sites whose affinity for Cs+ is sufficiently lower than that for Na+.     

Lithium transport pathways in human red blood cells

In human red cells, Li is extruded against its own concentration gradient if the external medium contains Na as a dominant cation. This uphill net Li extrusion occurs in the presence of external Na but not K, Rb, Cs, choline, Mg, or Ca, is ouabain-insensitive, inhibited by phloretin, and does not require the presence of cellular ATP. Li influx into human red cells has a ouabain-sensitive and a ouabain-insensitive but phloretin-sensitive component. Ouabain-sensitive Li influx is competitively inhibited by external K and Na and probably involves the site on which the Na-K pump normally transports K into red cells. Ouabain does not inhibit Li efflux from red cells containing Li concentrations below 10 mM in the presence of high internal Na or K, whereas a ouabain-sensitive Li efflux can be measured in cells loaded to contain 140 mM Li in the presence of little or no internal Na or K. Ouabain-insensitive Li efflux is stimulated by external Na and not by K, Rb, Cs, choline, Mg, or Ca ions. Na-dependent Li efflux does not require the presence of cellular ATP and is inhibited by phloretin, furosemide, quinine, and quinidine. Experiments carried out in cells loaded in the presence of nystatin to contain either only K or only Na show that the ouabain-insensitive, phloretin-inhibited Li movements into or out of human red cells are stimulated by Na on the trans side and inhibited by Na on the cis side of the red cell membrane. The characteristics of the Na-dependent unidirectional Li fluxes and uphill Li extrusion are similar, suggesting that they are mediated by the same Na-Li countertransport system.     

Taxonomic character of plant species in absorbing and accumulating alkali and alkaline earth metals grown in temperate forest of Japan

Summary Absorption and accumulation of alkali (Li, Na, K, Rb, Cs) and alkaline earth (Mg, Ca, Sr, Ba) metals were investigated as taxonomic characteristics (in 62 plant species). Leaf and soil samples were collected from 9 sites in temperature forest in Japan and the above mentioned elements were analyzed. Considerable differences were found among species in their ability to accumulate alkali and alkaline earth metals. Very high concentrations of Li (45 ppm, D.W.), K (37×10³ ppm), Rb (159 ppm) and Cs (8.2 ppm) were detected inLastrea japonica which were about 412, 12, 27 and 6 times higher than those of the species with the lowest concentrations. Na content was high inAcer micranthum (358 ppm) which was 16 times higher than species with the lowest concentration. Other species containing high levels of alkali metals wereHydrangea macrophylla, Struthiopteris niponica, Clethra barbinervis. Mean discrimination ratio (D.R.) for all investigated plant species for Li, Na, Rb, and Cs to K were 1.7, 0.44, 0.9 and 1.8 respectively. High concentrations of alkaline earth metals Ca (36×10³ ppm), Sr (345 ppm), and Ba (241 ppm) were found in the leaves ofHydrangea paniculata which were about 31, 84, and 72 times higher than those for the species with the lowest concentration. Mg was very high inStruthiopteris niponica (83×10² ppm). Other species with high concentrations of alkaline earth metals belonged to the genus Viburnum. Mean D.Rs. for Mg, Sr, and Bavs Ca were 1.0, 0.7 and 0.08. Principal component analysis of interrelationships between the mineral content in leaf tissues indicated that these elements could be classified into 2 groups with respect to their accumulation behavior in plants. The alkali metals K, Li, Rb, and Cs behaved similarly in their accumulation in leaves but Na behaved independently. Alkaline earth metals Ca, Mg, Sr, and Ba were also found to behave similarly in their accumulation. Factors scores of 1st and 2nd components revealed three groups of plant species: alkaliphilic, alkaline earthphilic, and neutral (non-accumulators).     

Distributions of Li+, Na+, K+, Rb+, and Cs+ tracer ions in erythrocytes at 38 °C in relation to entry rates of these ions into cells at 0 °C

Forces that are able to transport Na+ and K+ into two compartments were investigated. A modified Nernst-Planck equation for coupled flows of electric current, water, and ions was integrated. The result shows that if alkali ions in the ion channel of the cell membrane are separated by their electric-current-induced inward flows against an electro-osmotic outward flow of water, the logarithms of the stationary cell/medium distributions of these ions should be proportional to the inverse of their diffusion mobilities. The relationship was tested in human erythrocytes. From inward and outward movements of tracer alkali ions, calculations were made to obtain their stationary distributions at infinite time. The cell/medium distributions determined in this way at 38 degrees C are Li+ = 0.59, 22Na+ = 0.044, 42K+ = 10.0, 86Rb+ = 11.9, and 137Cs+ = 3.07. The entry rates of ions into the cell at 0 degrees C are understood to represent their diffusion mobilities in the pump channel. The entry rates are Li+ = 1.44, 2Na+ = 1, 42K+ = 2.22, 86Rb+ = 2.39, and 137Cs+ = 1.72 relative to that of 22Na+. There is an expected negative correlation between the logarithms of the stationary cell/ medium distributions at 38 degrees C and the inverse of the entry rates into the cell at 0 degrees C for the five ions. It is suggested that the proposed physical forces cause the separation of alkali ions in the channel of Na,K-ATPase.     

Sodium, an Obligate Growth Requirement for Predominant Rumen Bacteria

Sodium is an obligate growth requirement for most currently recognized predominant species of rumen bacteria. The isoosmotic deletion of Na(+) from a nutritionally adequate defined medium completely eliminated growth of most species. Growth yields and rates were both a function of Na(+) concentration for Na(+)-requiring species, and Na(+) could not be replaced by Rb(+), Li(+), or Cs(+) when these ions were substituted for Na(+) at a concentration equivalent to an Na(+) concentration that supported abundant growth. Li(+), Cs(+), or Rb(+) was toxic at an Na(+)-replacing concentration (15 mM) but not at a K(+)-replacing concentration (0.65 mM). K(+) was also an obligate growth requirement for rumen bacteria in media containing Na(+) and K(+) as major monovalent cations, but K(+) could be replaced, for most species, by Rb(+). The quantities of Na(+) that support rapid and abundant growth of Na(+)-requiring rumen bacteria show that these organisms are slight halophiles. A growth requirement for Na(+) appears more frequent among nonmarine bacteria than has been previously believed.