Blood plasma electrolyte concentrations

One of the posterior pituitary hormones—antidiuretic hormone (ADH, vasopressin)—may play a part in the metabolic response to injury. The reduced blood volume and increased plasma electrolyte concentration found after trauma may be expected to stimulate ADH secretion and the oliguria or anuria often found to follow injury would surest this is so (J2). 

Coulter, D. B., and L. L. Small. 1971. Effects of hemolysis on plasma electrolyte concentrations of canine and porcine blood. Cornell Veterinarian 61 660-666. 

Laboratory assessment of the composition of the blood plasma is often carried out in clinical chemistry. Among the electrolytes, there is a relatively high concentration of Na"", Ca and Cl ions in the blood in comparison with the cytoplasm. By contrast, the concentrations of IC, Mg "", and phosphate ions are higher in the cells. Proteins also have a higher intracellular concentration. The electrolyte composition of blood plasma is similar to that of seawater, due to the evolution of early forms of life in the sea. The solution known as physiological saline" (NaCl at a concentration of 0.15 mol L ) is almost isotonic with blood plasma. 

Instruments are offered in the market for clinical determination of electrolytes in blood, plasma or serum. One of them, for example, carries out simultaneous determinations of Na, K, Ca, Mg, hematocrit and pH. The cations are of the free type (see Section m.A) and are measured with specific ion-selective electrodes. In complex matrices such as blood or its derived fractions the concentration of free Ca and Mg is affected by the pH of the solution, for example, a slight change of pH will produce or neutralize anionic sites in the proteins, binding or releasing these cations furthermore, the response of the Mg-selective electrode is also affected by the concentration of free Ca(II). The correction... 

The regional poison centers certified by the American Association of Poison Control have reported 55 cases of metformin ingestion by children (128). Unintentional ingestion of 1700 mg of metformin did not pose health risks. In 21 children tested for blood glucose, lactate, or electrolytes, there was no evidence of lactic acidosis. Plasma metformin concentrations were not determined. 

Dofetilide is 100% bioavailable. Verapamil increases peak plasma dofetilide concentration by increasing intestinal blood flow. Eighty percent of an oral dose is eliminated by the kidneys unchanged the remainder is eliminated by the kidneys as inactive metabolites. Inhibitors of the renal cation secretion mechanism, eg, cimetidine, prolong the half-life of dofetilide. Since the QT-prolonging effects and risks of ventricular proarrhythmia are directly related to plasma concentration, dofetilide dose must be based on the estimated creatinine clearance. Treatment with dofetilide should be initiated in hospital after baseline measurement of the QTc and serum electrolytes. A baseline QTC of > 450 ms (500 ms in the presence of an intraventricular conduction delay), bradycardia of < 50 beats/min, and hypokalemia are relative contraindications to its use. 

Bito L, Davson H, Levin E, Murray M, Snider N. The concentrations of free amino acids and other electrolytes in cerebrospinal fluid, in vivo dialysate of brain, and blood plasma of the dog. Journal of Neurochemistry 1966, 13, 1057-1067. 

Renal function is an indication of the physiological state of the kidney glomerular filtration rate (GFR) describes the flow rate of Altered fluid through the kidney, while creatinine clearance rate (Ccr) is the volume of blood plasma that is cleared of creatinine per unit time, and is a useful measure for approximating the GFR. Most clinical tests use the plasma concentrations of the waste substances of creatinine and urea, as well as electrolytes, to determine renal function. The nephron is the functional unit of the kidney (Figure 10.1) it consists of two parts ... 

Changes in biochemical composition of CSF could serve as a useful tool for investigations of pathological processes in the CNS. CSF is also in contact wdth the blood plasma through the blood-brain barrier, thus resembling an ultrafiltrate of plasma in its protein constituents. CSF contains sugars, lipids, electrolytes and proteins. Protein concentration in CSF ranges from 0.2mg/ml to 0.8mg/ml (0.3 - 1% of serum protein concentration) wdth more than 70% of the proteins in CSF... 

Abnormalities of acid-base status of the blood are always accompanied by characteristic changes in electrolyte concentrations in the plasma, especially in metabolic acid-base disorders. Hydrogen ions cannot accumulate without concomitant accumulation of anions, such as CL or lactate, or without exchange for cations, such as or NaL Consequently, electrolyte composition of blood serum or plasma is often determined along with measurements of blood gases and pH and to assess acid-base disturbances. 

The membrane separates the blood from a dialyzing solution, or dialysate, that is similar to blood plasma in its concentration of needed substances (e.g., electrolytes and amino acids) but contains none of the waste products. Because the concentrations of undesirable substances are thus higher in the blood than in the dialysate, they flow preferentially out of the blood and are washed away. The concentrations of needed substances are the same on both sides of the membrane, so these substances are maintained at the proper concentrations in the blood. The small pore size of the membrane prevents passage of blood cells. However, Na and Cl ions and some small molecules do pass through the membrane. A patient with total kidney failure may require up to four hemodialysis sessions per week, at 3 to 4 hours per session. To help hold down the cost of such treatment, the dialysate solution is later purified by a combination of filtration, distillation, and reverse osmosis and is then reused. 

The pancreatic secretion of chloride varies inversely to the bicarbonate concentration, which in turn varies directly with the flow rate the sum of these two anions tends to remain constant under physiological conditions, with the electrolyte concentrations of the pancreatic secretions tending to parallel blood pH and electrolytes. Excessive losses of pancreatic fluid can be monitored by plasma chloride measurements. Hypocalcemia may also accompany severe pancreatic toxicity, probably due to the formation of insoluble salts with fatty acids. 

The ubiquitous role of chloride (as dissolved sodium chloride) in animal and human cells and blood plasma is manifold as just discussed, it provides Cl for organosynthesis and to control the electrolytic properties such as osmosis (a process where water molecules move through a semipermeable membrane from a dilute solution into a more concentrated solution), for nutrient and waste transport, as well as providing electrical gradients (based on conductivity) for information transfer through neurons. 

The body fluids do not constitute a homogeneous solution of electrolytes. Body fluids are classically categorized as intracellular and extracellular. The extracellular compartment is further divided into an intra- and extravascular compartment. The intravascular fluid constitutes the blood plasma, but even blood plasma does not form a homogeneous compartment. The composition of plasma varies with anatomical location and physiological conditions. The electrolyte compositions of plasma obtained from venous and arterial blood differ, and there are diurnal variations in the electrolyte concentrations of the plasma. 

The alkali metal ions play an important role in human physiology, however. Sodium and potassium ions are major components of blood plasma and intracellular fluid, respectively with average concentrations on the order of 0.1 M. These electrolytes serve as vital charge carriers in normal cellular function, and they are two of the principal ions involved in regulation of the heart... 

Attempts to raise the concentrations of calcium and/or phosphate in saliva with a view to decreasing enamel solubility have not been successful. The calcium ion is the most closely regulated of the plasma electrolytes and remains constant in spite of variations in dietary intake. Neither supplementation of the diet of rats with moderate amounts of inorganic phosphate nor infusion of human subjects with sufficient phosphate to bring about a threefold increase in blood levels caused an appreciable change in the phosphate concentration of saliva. Nevertheless, rats fed a phosphate supplement showed a marked reduction in caries, presumably as the result of a local effect. 

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