Sodium sensitivity

Kennedy, L.T. and Hanbauer, I., Sodium-sensitive cocaine binding to rat striatal membrane possible relationship to dopamine uptake sites, J. Neurochem., 41, 172, 1983. 

Tissue electrodes [2, 3, 4, 5, 45,57], In these biosensors, a thin layer of tissue is attached to the internal sensor. The enzymic reactions taking place in the tissue liberate products sensed by the internal sensor. In the glutamine electrode [5, 45], a thick layer (about 0.05 mm) of porcine liver is used and in the adenosine-5 -monophosphate electrode [4], a layer of rabbit muscle tissue. In both cases, the ammonia gas probe is the indicator electrode. Various types of enzyme, bacterial and tissue electrodes were compared [2]. In an adenosine electrode a mixture of cells obtained from the outer (mucosal) side of a mouse small intestine was used [3j. The stability of all these electrodes increases in the presence of sodium azide in the solution that prevents bacterial decomposition of the tissue. In an electrode specific for the antidiuretic hormone [57], toad bladder is placed over the membrane of a sodium-sensitive glass electrode. In the presence of the antidiuretic hormone, sodium ions are transported through the bladder and the sodium electrode response depends on the hormone concentration. 

A relatively new and promising area of research concerns the role of inadequate dietary calcium in the development of essential hypertension or high blood pressure (Villar et al. 1986 Karanja and McCarron 1986 Resnick 1985 NDC 1984A.B McCarron 1985, 1983, 1982 McCarron et al. 1982). While most reports relating diet to hypertension have emphasized sodium, it appears that only a small proportion of the U.S. population is genetically sodium sensitive and that for the majority, dietary sodium intake has little effect on blood pressure. As discussed below, inadequate calcium intake, either alone or in combination with other factors, appears to predispose to high blood pressure by a mechanism(s) as yet unknown. 

Pringsheim5 has reviewed some of the early qualitative experiments. Beutler and Josephy139 examined the fluorescence of sodium sensitized by mercury, and concluded that the process with the largest cross-section is... 

Gil-Mascarell, R., Lopez-Coronado, J.M., Belles, J.M., Serrano, R., Rodriguez, P.L., Murguia, J.R., Quintero, F.J., Garciadeblas, B., and Rodriguez-Navarro, A., 1999, The Arabidopsis Hal2-like gene family includes a novel sodium-sensitive phosphatase. Plant J. 17 373-383. 

Lopez, F., Leube, M., Gil-Mascarell, R., Navarro-Avino, J.P., and Serrano, R., 1999, The yeast inositol monophosphatase is a lithium- and sodium-sensitive enzyme encoded by a non-essential gene pair. Mol. Microbiol. 31 1255-1264. 

Race definitely comes into play. High blood pressure is far more common in blacks than in any other racial group, and it hits at an earlier age. But we know that African Americans are far more sodium sensitive than whites are and at the same time they have diets that are high in sodium, doubling the problem. The solution seems pretty obvious. Similarly, obesity and diabetes are more prevalent among blacks. Rather than wringing his or her hands in despair, the wise black individual will take appropriate action. 

Sodium and salt intake remain controversial as risk factors for hypertension. While it s true that some individuals are particularly sensitive to sodium, whether from the salt shaker or from sodium-based ingredients in processed and fast foods, not everyone responds to sodium equally. As we ll see, sodium is but one of many minerals, or electrolytes, that affect blood pressure. Increasing your intake of the others may be as important as, or more important than, decreasing your intake of sodium, other than for people who are proven to be sodium sensitive. 

Heart authorities in the United States, the United Kingdom, Australia, and just about everywhere else urge citizens to cut back, way back, on salt and sodium consumption. For many people, this can help them to control hypertension. That s especially true for blacks and older men and women, all of whom are more salt sensitive than others. About 25 to 50 percent, perhaps more, of people with hypertension—not necessarily mildly elevated blood pressure—are sodium sensitive. Blacks have a higher rate of sodium sensitivity, but that leaves a lot of men and women who are not. 

There s no doubt that genetics play a major role in how the body deals with sodium. The way our kidneys handle salt and sodium makes the difference. Let s look at a study done with rats in the laboratory that are bred to be either sodium sensitive or sodium resistant. The blood pressure of sensitive rats goes up... 

Within those groups, however, were men and women who were very sensitive to sodium. Salt or sodium sensitivity is a very real thing. Researchers are now trying to develop a test for such sensitivity so that physicians can know which patients need sodium restriction and which do not, rather than prescribing it for everyone. That test is still in the future, but the zealots say we don t need such a test because if everyone greatly restricted sodium intake, some people would benefit and society would be the better for it. Maybe some day we ll have that sensitivity test, and maybe not. In the meantime, we do know that African Americans, older individuals,... 

Certain population groups are also served better by particular drugs. Studies have found and physicians have observed over the years that people who are sodium sensitive and/or who are members of an ethnic group such as African Americans whose diet is heavy on salt will frequently do best with diuretic drugs, calcium channel blockers, or both. 

G protein-coupled receptor kinase 4 (GRK4) Arg65Leu, Alal42Val, and Ala486Vval Hypertension, sodium sensitivity GRK4 activity increased t Dopamine 1/ receptor desensitization t Angiotensin II type 1 receptor expression [201-203]... 

Potassium replacement is recommended in patients who are sodium sensitive, and in hypertensive patients. 

Studies on monoamine inactivation mechanisms in insects have yielded equivocal results with N-acetylation (6-9), oxidative deamination (10,11) and -sulphate or 6-alanyl conjugation (12,13) proposed as possible routes of monoamine catabolism however, the weight of evidence favours N-acetylation as the principal mechanism of monoamine breakdown Sodium-sensitive and sodium-insensitive uptake mechanisms for OA have also been described in the cockroach central nervous system (14). 

Another Simon s ionophore (ETH 227) (Fluka 71176) is now the choice for making Na1 -measuring cocktail. Before this, monensine antibiotic-based sodium-sensitive pipettes were used (47) but suffered from high K+ interference. 

The sodium-sensitive type of electrode can be used to determine the activity of sodium ion in the presence of appreciable amounts of potassium ion. Its selectivity for sodium over potassium is on the order of 3000 or more. Glass electrodes can be obtained that show a selectivity ratio for silver over sodium of greater than 1000. Glass electrodes can be used in liquid ammonia and molten salt media. 

We have formulated this problem in a manner that considers only Na and as active species. Glass membranes also respond to other ions, such as Li, K", Ag, and NH4. The relative responses can be expressed through the corresponding potentiometric selectivity coefficients (see Problem 2.16 for some typical numbers), which are influenced to a great extent by the composition of the glass. Different types of electrodes, based on different types of glass, are marketed. They are broadly classified as (a) pH electrodes with a selectivity order >>> Na" > K, Rb", Cs >> Ca , (b) sodium-sensitive electrodes with the order Ag > > Na >> K, Li >> Ca ", and (c) a more... 

Various mechanisms have been studied in relation to the inactivation of monoamines in insects, which include V-acetylation, oxidative deamination, ° 0-sulfate or (S-alanyl conjugation, and sodium-sensitive and sodium-insensitive uptake mechanisms. GC and MS properties were determined for a variety of biogenic amines as their DTFMB-TMS and DTFMB-TBDMS derivatives. Since the first application of HPLC-ED, it has become an increasingly important analytical tool on neuroscience. Recently, microbore HPLC-ED has become the method of choice for the determination of trace biogenic amines and their metabolites. 

Koski, G., Streaty, R.A. and Klee, W.A. (1981) Modulation of sodium-sensitive GTPase by partial opiate agonists. J. Biol. Chem. 257 14035-14040. 

The construction of ISEs used in clinical measurements is of the membrane electrode type, i.e., the ion-sensitive membrane separates the sample from an internal reference electrolyte, which is the site of the internal reference element, usually a silver wire covered by silver chloride. The membrane can be shaped to different forms such as flat, convex, tubular, etc. Sodium sensitive membranes are made from special composition glass, the other ion-sensitive membranes from a polymer matrix such as plasticized polyvinylchloride (PVC) or silicon rubber. The particular selectivity of polymer membranes is first of all due to a small percentage of active material, e.g., valinomycin, dissolved in the polymer. Important secondary effects have been attributed to the type and permittivity of the polymer. The useful lifetime of the sensors also depends on the polymer. The time response [13] may again depend on membrane composition. 

Glassy and Impervious carbon High temperature capabilities over the entire acidic range but damaged by liquid sodium sensitive to mechanical stress upon cooling... 

Thomas, R.C. New Design for Sodium-Sensitive Glass Microelectrodes. J. Physiol. 1970, 82P. 

Among the active substances useful for single-charged cations, in particular for the analytically important alkali metal ions, are naturally occurring antibiotics like the valinomycin mentioned already or monensin, which can be used to set up a sodium-sensitive electrode. Substance a in Fig. 7.8 (dicyclo-18-crown-6) belongs to the group of cyclic polyethers, the so-called crown... 

The calixarenes (e.g. methyl-p-tert-butylcahx[4]arylacetate in Table 7.3 and f in Fig. 7.8 are molecules that resemble a vase. They are synthesized by reaction of substituted phenols with aldehydes. The molecules have hydrophobic cavities which can hold sample ions. As an example, a sodium-sensitive electrode with polymer membrane has been designed as shown in Fig. 7.6, right (Diamond et al. 1988). 

Klenerman and coworkers have utilized potential-controlled delivery of water-soluble analytes from nanopipettes in a system which is entirely aqueous. Pulsed voltage-driven delivery of ions was performed from nanopipettes at close proximity to a surface, and the localized concentration profiles were measured immediately with total internal reflectance fluorescence (TIRF) microscopy (Figure 11.14B). Their studies found that the total concentration of analyte delivered was dependent on the size of the nanopipette, applied potential difference, height above the surface during delivery, and initial analyte concentration within the pipette. This localized delivery system was then applied to cellular studies in which the sodium-sensitive E. coli flagellar motor was dosed with Na+ ions. The cellular response of the speed of motor movement was observed and matched well with previously determined dosing profiles under defined delivery conditions. 

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