Cesium physiology

The anthropogenic radionuclides of most concern are those produced as fission products from nuclear weapons and nuclear reactors. The most devastating release from the latter source to date resulted from the April 26, 1986, explosion, partial meltdown of the reactor core, and breach of confinement structures by a power reactor at Chernobyl in the Ukraine. This disaster released 5 x 107 Ci of radionuclides from the site, which contaminated large areas of Soviet Ukraine and Byelorussia, as well as areas of Scandinavia, Italy, France, Poland, Turkey, and Greece. Radioactive fission products that are the same or similar to elements involved in life processes can be particularly hazardous. One of these is radioactive iodine, which tends to accumulate in the thyroid gland, which may develop cancer or otherwise be damaged as a result. Radioactive cesium exists as the Cs+ ion and is similar to sodium and potassium in its physiological behavior. Radioactive strontium forms the Sr2+ ion and substitutes for Ca2+, especially in bone. 

Bearing in mind these cautions, the permeability to calcium is around 1/10 to 1/5 of that to sodium or cesium ions for mammalian muscle receptors of the embryonic type (native or recombinant), and is much higher (0.5-0.9) for the adult form of the receptor (133-135). This is in agreement with estimates that calcium ions carry approximately 2% and 4% of the total nicotinic current through embryonic and adult muscle receptors, respectively [at physiological calcium concentrations and holding potentials (136-138)]. 

Ringer ST (1982/83) An investigation concerning the action of rubidium and cesium salts compared with the action of potassium salts on the ventricles of the frogs heart. J Physiolog 4 270-276. 

Klockner, U. and Isenberg, G. (1985) Calcium currents of cesium loaded isolated smooth muscle cells (urinary bladder of the guinea pig). Pflugers Archiv - European Journal of Physiology, 405 340-348. 

Some radionuclides are physiologically similar to their nonradioactive, stable isotopes for example, tritium behaves like stable hydrogen, and follows C pathways. Actually, both tritium and are used to stutfy the physiological pathways of their stable isotopes. This isotopic substitution tends to work for all radionuclides, although there is often a shght discrimination because of differences in molecular weight. In addition, some elements with similar characteristics in the periodic table often behave similarly. For example, cesium (e.g., Cs) and potassium have similar chemical characteristics, so that often cesium isotopes follow potassium pathways. This similarity also occurs within animals, most notably when radium (e.g., Ra) follows calcium pathways and is deposited in bone. 

A major and striking physicochemical difference between lithocholic acid and the dihydroxy and trihydroxy bile acids is the insolubility of the sodium salts of the former (10, 45). Sodium salts of the common bile acids (taurine and glycine conjugates of cholic acid, deoxycholic acid, and che-nodeoxycholic acid) are very soluble in water and physiological saline, even at 0°C. The solubility of the ammonium, lithium, sodium, potassium, rubidium, and cesium salts of lithocholic acid (NH4L, LiL, NaL, RbL, CsL) have been studied in water as a function of temperature (45). 

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