Sodium activation

Bers, D.M. and Ellis, D. (1982). Intracellular calcium and sodium activity in sheep heart Purkinje fibres. Effects of changes of external sodium and intracellular pH. Pflugers Arch. Eur. J. Physiol. 393, 171-178. 

Blankemeyer, J.T. and C.R. Hefler. 1990. Effect of naphthalene on sodium active transport in the frog skin. Bull. Environ. Contam. Toxicol. 45 627-632. 

Abnormal neuronal calcium and sodium activity and homeostasis cause neurotransmitter dysreguiation. 

Blaustein MP, Golovina VA 2001 Structural complexity and functional diversity of endoplasmic reticulum Ca2+ stores. Trends Neurosci 24 602-608 Boyett MR, Hart G, Levi A J 1986 Dissociation between force and intracellular sodium activity with strophanthidin in isolated sheep Purkinje fibres. J Physiol 381 311—331... 

Electrolyte disturbances have been extensively studied, with disruptions in calcium and sodium activity the most consistently reported aberrations in mood disorders. 

Calcium antagonists (e.g., verapamil, nimodipine) can also block dopamine, 5-HT, and endorphin activity, alter sodium activity via a sodium-calcium counter-exchange, and act as anticonvulsants. Any or all of these actions could be involved in their putative antimanic effects ( 35). 

Thus soils which contain kaolinite in well-drained profiles will be montmorillonite-bearing in stagnant zones. This evolution is accounted for by a movement towards higher sodium activity in Figure 36. 

More recently, Blankemeyer et al. studied the effect of tomatine and tomatidine on frog embryos and frog skin. They found that tomatine increased membrane permeability in frog embryos and decreased sodium-active transport in frog skin, in contrast to the essentially negative results with tomatidine [62]. This reinforces the hypothesis that the carbohydrate side-chain is essential for the glycoalkaloid activity. 

The process of chain transfer has received very little quantitative study insofar as the anionic systems are concerned. The first study of an anionic chain transfer process was that of Robertson and Marion 274) on the polymerization of 1,3-butadiene by sodium in toluene. The reaction of toluene with the sodium active center led to the formation of benzyl sodium. This work was the first to demonstrate the important role of solvent in transfer reactions involving anionic active centers ... 

In contrast to the claim of Szwarc and co-workers 291) that the a-methyl(styryl)-sodium active center is stable, measurements from various sources have shown 293 30l) that transformations readily occur. The dimer structure formed froma-methyl styrene and sodium is as follows ... 

Fig. 9.6 Top intracellular sodium activity and tension recorded in a cardiac Purkinje fiber during rest and during a period of repetitive stimulation at 2 Hz [28]. Middle reconstruction using a model ventricular cell showing intracellular sodium and calcium...

There are no new principles involved as far as an electrolytic sensor is concerned. The electrolyte membrane is /i-alumina and the reference sodium activity fixed, at constant oxygen activity, by a mixture of sodium ferrite (Na10Fe16O29, which can be written 5Na20 8Fe203) and Fe203, just as it is common practice to fix oxygen activity by a mixture of a metal and its oxide. 

Glass electrode — An electrode (sensor) for the measurement of ion, especially hydronium (- pH) and alkali ion (pNa) -> activities in aqueous [i], and, less often, nonaqueous solutions. Glass electrodes are also applicable for measuring deutonium (D3sodium activities in heavy water (D2O) solutions [ii]. 

The crystal stmctures of several sodium- and potassium-activated enzymes have now been determined and the position of the monovalent cation estabhshed. Structural data are listed in the Protein Data Bank (PDB). They provide a clue (but not an absolute proof) to their location within the enzyme on activation. Further biochemical studies may be necessary to verify this finding. Some examples of these structures are presented here. The first example (thrombin) is a sodium-activated enzyme, but the others are potassium-activated enzymes. 

E515 Eastep, S.J., Benson, P.J., Preese, L.M. and Apple, F.S. (1989). Factitiously high sodium activities on the Ektachem 400 owing to interferences by high gammaglobulin concentrations. Clin. Chem. 35, 333-334. 

Kaesemeyer WH, Caldwell RB, Huang J, Caldwell RW. 1999. Pravastatin sodium activates endothelial nitric oxide synthase independent of its cholesterollowering actions. J. Am. Coll. Cardiol. 33 234 11... 

Hence, the sodium activity - and thus the cell potential - is related to the SO2 partial pressure. The auxiliary electrode must be in contact with both the electrolyte (with the mobile sodium ions) and the metal electrode (to measure the electrical signal), as well as the gas consequently, porous electrodes are typically used to provide a large three-phase-boundary area. It is also possible to mix the auxiliary electrode with the electrode either only near the surface (where it is needed) or throughout the electrolyte (which is sometimes easier to fabricate) this is referred to as a composite electrolyte. 

Yao, P.C. and Fray, D.J. (1985) Sodium activity determinations in molten 99.5% aluminium using solid electrolytes. J. Appl. Electrochem., 15, 379-86. 

Brisley, R.J. and Fray, D.J. (1983) Determination of the sodium activity in aluminum and aluminum silicon alloys using sodium beta alumina. Metall. Trans. 

This decrease corresponded to the development of a small resting current (Fig. 30, Fig. 4A). The difference between the normal sodium activation curve (dotted line) and the slow insecticide-... 

C Conductance-potential relationship for the peak (A) and tail currents 10 min. (v) and 22 min. ( ) after application of the insecticide. The peak conductance was tentatively fitted with a normal sodium activation curve shifted by 10 mV towards more positive membrane potentials. After 10 min., the tail current could still be fitted with a similar curve whereas, after 22 min., the voltage-dependency was reduced by one half and a resting sodium conductance appeared. Modified from (11). 

Fig.4 Voltage (A) and time (B) dependency of the tail current following a 20 min treatment of the axon with 5pM S-bioallethrin. Here again, the voltage sensitivity (A) of the tail conductance could no longer be fitted with the normal sodium activation curve (dotted line) but exhibited a reduced voltage sensitivity (interrupted line). In B, the experimental data could be fitted with a combination of a step increase and a slow exponential increase consistent with the model presented in the text. Modified from (10).

Fig.5 A Voltage-sentitivity of m5 ( the steady-state value of the sodium activation parameter raised to the fifth power to describe the sodium current in insect nerves, see 19 and 20), and of the insecticide induced sodium conductance (p). B voltage-sensitivity of the corresponding time constants of activation (tau m and tau p). Tau p is larger that tau m by a factor of 10 to 1000, depending on the nature of the insecticide, its concentration and time. The values used for the computations illustrated in this paper were derived from experiments on pyrethroid I.

The influence of the charge peirameter and of the distribution pattern of carboxyl groups on the interaction polyanion-counterion (sodium or calcium) were studied by the determination of calcium and sodium activity coefficients which were compared to theoretical values. 

The calcium and sodium activity coefficients were determined at 25.0 - 0.1 C with an Orion electrode (model 92-32) and a Radiometer electrode (model G502 Na), respectively. A saturated calomel electrode was used as the reference. Calibration curves were obtained using CaCl or NaCl solutions before and after each measurement. The CaCl2 and NaCl concentrations were measured by potentiometric determinations of the chlorides with silver nitrate and with a silver electrode. 

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