In a three-year (2004-2006), field experiment, we aimed to study changes in leaf physiological traits (leaf water potential-Ψleaf, leaf water content-LWC, carbon isotope discrimination-Δ, specific leaf area-SLA, chlorophyll content as assessed by SPAD and modified SPAD-MSPAD) and elemental composition (K, Na, Ca, Mg, K/Na, Ca/Mg, total leaf salinity-TLS) of sugar beets (cv. Rizor) grown unde...

Tissue-distinct interactions of the Na+-K+-ATPase with Na+ and K+, independent of isoform-specific properties, were reported previously (A. G. Therien, N. B. Nestor, W. J. Ball, and R. Blostein. J. Biol. Chem. 271: 7104-7112, 1996). In this paper, we describe a detailed analysis of tissue-specific kinetics particularly relevant to regulation of pump activity by intracellular K+, namely K+ inhib...

Na+/K(+)-ATPase activity was demonstrated in the midgut of Anopheles stephensi. More than 80% of the total ATPase activity was sensitive to inhibition by ouabain with an IC50 of 4.5 x 10(-7) +/- 0.3 x 10(-7) mol l-1 and with maximal inhibition occurring at 10(-4) mol l-1. This ouabain-sensitive Na+/K(+)-ATPase was maximally activated at a Mg2+:ATP ratio of 1:1.3, with a Km of 0.3 mmol l-1 and a...

BACKGROUND Previous studies that reported an association of dietary Na(+) intake with metabolic syndrome were limited by the use of imprecise measures of obesity, Na(+) intake, or exclusion of multiethnic populations. The effect of dietary K(+) intake on obesity is less well described. OBJECTIVE We hypothesized that high dietary Na(+) and low K(+), based on the ratio of urinary Na(+) to K(+) ...

Effects of diphenylhydantoins on (Na(+) + K(+))-ATPase activity in rat and cat brain microsomes were studied. 5,5-diphenylhydantoin (DPH) in concentrations of 5-20 mug ml(-1) produces an apparent stimulation of the rat brain (Na(+) + K(+))-activated ATPase of 55-65% in media containing 50 mM Na(+), 0.15 mM K(+), 3 mM Mg(++), and 3 mM ATP. No effects are found on the Mg-ATPase. At constant K(+) ...

To determine if salt tolerance of grafted cucumber can be associated with the accumulation of organic solutes and inorganic solutes in the leaves and roots, a salt-sensitive cucumber cultivar Jinchun No. 2 (Cucumis sativus L.) was grafted onto the commercial salt-tolerant bottle gourd cultivar Chaofeng 8848 (Lagenaria siceraria Standl.). Grafted and ungrafted plants were grown in hydroponic sys...

Newt oocytes were dissected under liquid paraffin and known volumes of clean nucleoplasm and cytoplasm were obtained from oocytes in different stages of oogenesis. The samples were digested in redistilled nitric acid, diluted with deionized water, and their Na and K contents were measured by flame spectrophotometry. The results were expressed as micro-equivalents of Na and K per millilitre of n...