Retention of Inorganic Substances

Electrolyte and acid-base disorders in chronic renal failure are well known and will therefore be presented briefly. A more detailed discussion may be found in standard textbooks of nephrology (M25). 

Hyperkalemia poses an immediate threat to the life of the uremic patient. Although potassium excretion decreases with increasing nephron loss, hyperkalemia occurs infrequently in stable chronic renal failure when the glomerular filtration rate exceeds 10 ml/minute. Serum potassium, however, may rise sharply if renal function deteriorates suddenly or if an excessive potassium load enters the extracellular fluid space. The latter event may result from dietary indiscretion extracellular shift of potassium by acidemia potassium release by hemolysis, rhabdomyolysis, or tumor lysis, or administration of potassium-containing drugs. 

Acute hyperkalemia causes a hypopolarization of the cardiac muscle cell membrane, resulting in characteristic electrocardiographic changes followed by serious and often fatal arrhythmias in most cases there are no warning symptoms. Immediate treatment is needed and consists of giving sodium bicarbonate, glucose, and insulin intravenously to shift K+ into the cells calcium intravenously to minimize the cardiotoxicity of hyperkalemia and polysterene sodium (a Na/K exchange resin) rectally or orally to remove potassium from the body if all fails, the performance of dialysis may be required (S18). 

Retention of sodium and water in progressive renal failure results in hypertension, edema, pleural and pericardial effusions, and pulmonary edema, the last being a life-threatening event requiring immediate dialysis. Hypertension may be severe, leading to heart failure or encephalopathy. Hyponatremia occurs if water is retained in excess of sodium. If severe, it may cause muscular twitching and convulsions (water intoxication). Dialysis is the treatment of choice (R14). 

Severe acidemia impairs cardiac contractility and predisposes to arrhythmias. Treatment with sodium bicarbonate or Shohl s solution (sodium citrate and citric acid) is in order if the blood pH falls below 7.2 (Nl). Dialysis should be started when uremia and acidosis are more advanced. 

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Countercurrent chromatography has been mainly developed and used for preparative and analytical separations of organic and bio-organic substances [1], The studies of the last several years have shown that the technique can be apphed to analytical and radiochemical separation, preconcentration, and purification of inorganic substances in solutions on a laboratory scale by the use of various two-phase liquid systems [2], Success in CCC separation depends on choosing a two-phase solvent system that provides the proper partition coefficient values for the compounds to be separated and satisfactory retention of the stationary phase. The number of potentially suitable CCC solvent systems can be so great that it may be difficult to select the most proper one. 

The absorption of copper from the bowel can be influenced by a number of inorganic substances. Anions, which have a tendency to form highly insoluble salts with copper under the conditions prevailing in bowel contents, tend to reduce the absorption of copper. Sulfide is the best known of these. Cupric sulfide is poorly absorbed by rats and pigs (B21, S23). Addition of sulfides to the diet markedly reduces copper absorption in animals (D5) and man (C5). Of the cations, molybdenum is known to influence copper retention in animals. It is suspected that molybdenum influences the membrane transport of copper in such a way that absorption is decreased and excretion increased (D6). For details of this problem the reader is referred to Underwood s monograph (U2) and a recent review by Mills (M25). Problems of this nature have not yet been encountered in man. Oral doses of potassium sulfide and certain ion-exchange resins are used to reduce the absorption of copper in certain pathological conditions in man (C5). 

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