Potassium is the principle intracellular ion, and its concentration and gradients greatly influence the electrical activity of excitable membranes. Because anaesthesia is so intimately involved with electrically active cells, potassium concentrations in surgical patients have received considerable attention in diagnostic and therapeutic applications. With the ongoing evolution in the indication...

Interest in culturing the Pacific white shrimp Litopenaeus vannamei in low-salinity and brackish-well waters has led to questions about the ability of this species to osmo- and ionoregulate in environments containing low concentrations of ions and in environments with ionic ratios that differ from those found in sea water. After seven days, hemolymph osmolality and potassium, sodium and calcium...

The intracellular sodium ion activity was measured using liquid ion-exchange microelectrodes with rapid response times in sheep Purkinje fibers and ventricular muscle under voltage control. The mean sodium ion activity in quiescent Purkinje fibers was 8.5 mM at a holding potential of -80 mV. With maintained hyperpolarizing (-110 mV) or depolarizing (-40 and 0 mV) voltage steps, sodium ion activ...

The opening rate of voltage-gated potassium ion channels exhibits a characteristic knee-like turnover where the common exponential voltage dependence changes suddenly into a linear one. An explanation of this puzzling crossover is put forward in terms of a stochastic first passage time analysis. The theory predicts that the exponential voltage dependence correlates with the exponential distribu...

drought stress is one of the most important problems of agriculture and an important factor of plant product reduction. application of absorbent materials can help usage of sporadic rain fall and cause more maintenance of water storage. in order to study the effect of super absorbent polymer, potassium sulfate and manure under drought condition and favorable irrigation on some traits of foxtail...

Department of Biology, Technische Universität-Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany (G.T.); Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan Italy (A.M.); Information Genomique and Structurale, Unité Mixte de Recherche 7256, Centre National de la Recherche Scientifique, Aix-Marseille Universite, FR–13288 Marseille, France (G.B.); and Department of...

The steady state kinetics of sodium and potassium ion transport adenosine triphosphatase (EC 3.6-l. 3) suggests an activating action of adenosine triphosphate in addition to its action as a phosphate donor. This action might be an acceleration of dissociation of Kf or its congeners from the enzyme. To test this possibility transient kinetics of the phosphoenzyme was investigated. In membranes f...

A method for the determination of selenium by ion chromatography (IC) after oxygen flask combustion has been developed and applied to the determination of selenium in bulk prednisolone. We found elemental selenium [Se(0)], selenite ion [Se(IV)] and selenate ion [Se(VI)] (ca. 5, 75 and 20%) in the absorbing liquid obtained by oxygen flask combustion of Se(0), Se(IV) and Se(VI). Se(VI) was direct...