The ion exchange mechanism of the sodium/calcium exchanger (NCX) crystallized by Liao et al. in 2012 is studied using the Poisson-Fermi theory developed by Liu and Eisenberg in 2014. A cycle of binding and unbinding is proposed to account for the Na(+)/Ca(2+) exchange function of the NCX molecule. Outputs of the theory include electric and steric fields of ions with different sizes, correlation...

Two recent studies reported that Na-Ca exchange in the outer segments of tiger salamander rod photoreceptors (Cervetto, L., Lagnado, L., Perry, R. J., Robinson, D. W., and McNaughton, P. A. (1989) Nature 337, 740-743) and of bovine rod photoreceptors (Schnetkamp, P. P. M., Basu, D. K., and Szerencsei, R. T. (1989) Am. J. Physiol. 257, C153-157) requires and transports K+ in a 4Na/(1Ca+1K) stoic...

NaCl hyperosmolarity increases intestinal blood flow during food absorption due in large part to increased NO production. We hypothesized that in vivo, sodium ions enter endothelial cells during NaCl hyperosmolarity as the first step to stimulate an increase in intestinal endothelial NO production. Perivascular NO concentration ([NO]) and blood flow were determined in the in vivo rat intestinal...

The initial velocity of Ca2+ uptake via the Na-Ca exchange system in cardiac sarcolemmal vesicles is competitively inhibited by extravesicular Na+. The Hill plots for multisite competitive inhibition are nonlinear, exhibiting a limiting slope of 1 at low Na+ concentrations (less than 20 mM) and 1.6-2.0 at higher concentrations. The Ki for Na+ is approximately 16 mM. Thus, the Ca2+ binding site ...

To ascertain the importance of sputtering by solar wind ions on the formation of a sodium exosphere around Mercury and the Moon, we have irradiated with 4 keV He ions, the Na bearing tectosilicates: albite, labradorite, and anorthoclase, as well as adsorbed Na layers deposited on albite and on olivine (a neosilicate that does not contain Na). Sodium at the surface and near surface (<40 Å) was q...

Na(+) strongly promoted HCO(3) (-) transport in Anabaena variabilis. The effect was highly specific to this cation. Kinetic analysis indicated a progressive decrease in the K(m) (HCO(3) (-)) of the transport system with increasing Na(+) concentration. V(max) was also affected. We raise the possibility that the transport is a Na(+)-HCO(3) (-) symport; alternatively, that a Na(+)-H(+) antiport (o...

The influxes of Na(+) and K(+) into the human red cell appear to be interrelated. This relationship was investigated under conditions in which either Na(+) or K(+) concentration outside the cell was varied or one cation was replaced by Mg(2+), choline(+), or Li(+). The effects of furosemide on Na(+) and K(+) movements were studied in the presence of ouabain. When ouabain was present, Na(+) infl...

[1] We have analyzed measurements of planetary ions near Mercury made by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Fast Imaging Plasma Spectrometer (FIPS) over the first three Mercury years of orbital observations (25 March 2011 through 31 December 2011). We determined the composition and spatial distributions of the most abundant species in the regions sampl...

Salinity stress is a brutal environmental stress which decreases the yield production of plants. Questions rise on which of the ionic stress or lack of water has deleterious effects on plants forage dry yield. Also, questions remain on whether the K+ reduction or Na+ accumulation is more important in forage dry yield reduction under salinity stress. The present experiment was conducted to answe...

Layered P2-Na(x)[Ni(1/3)Mn(2/3)]O(2) (0 < x < 2/3) is investigated as a cathode material for Na-ion batteries. A combination of first principles computation, electrochemical and synchrotron characterizations is conducted to elucidate the working mechanism for the improved electrochemical properties. The reversible phase transformation from P2 to O2 is observed. New configurations of Na-ions and...