Potassium in blood

To evaluate the precision for the determination of potassium in blood serum, duplicate analyses were performed on six samples, yielding the following results. 

PET-5, PET-6 and PET-7 are examples of macrobicydic structures (cryptands) (Figure 10.12). The cavity of PET-6 and PET-7 fits well the size of K+. PET-6 has been successfully used for monitoring levels of potassium in blood and across biological membranes, but pH must be controlled because of pH sensitivity of this compound via protonation of the nitrogen atoms. This difficulty has been elegantly overcome in benzannelated cryptand PET-7, in which the aromatic nitrogens have lower pKa than those of aliphatic amines. 

In addition to automated analysers for general use, sophisticated single purpose instruments have been developed and marketed, chiefly for clinical analyses (for example Astra 4 and Astra 8 from Beckman for the determination of sodium and potassium in blood or Orion Space-Stat SS-20 or SS-30 for the determination of calcium in blood). 

Willis (Wll), using a potassium hollow cathode tube instead of the commonly employed discharge lamp, determined potassium in blood serum. At the 1 50 dilution no interference was encountered from calcium, magnesium, and phosphate at serum levels, but sodium gave a small enhancement. The sodium interference was controlled by the addition in excess of sodium chloride or of the disodium salt of EDTA to samples and standards alike. 

Herrmann and Lang (H3) also determined potassium in blood serum. Calibration curves were straight from 1 to 100 mg sodium per liter. One wonders about the sensitivity of their technique since it is stated that the serum dilution used was 1 5. 

Many of the components of injury can influence aldosterone secretion, and sodium depletion and hypovolemia are probably the most important (B7, S5). Hemorrhage alone can also stimulate aldosterone secretion rate. A raised concentration of potassium in blood and excess 5-hydroxy-tryptamine from injured tissues have both been shown to increase aldosterone secretion (Mil). 

The range of normal plasma potassium for humans (i.e., normokalemia) is defined as 140-200 mg L f and hyperkalemia as > 200 mg L f Both hypo- and hyperkalemia are associated with potentially fatal cardiac arrhythmia (Peterson 1997). However, different species of animals display differences in the distribution of potassium in blood plasma (cow 240 mg L f pig 220 mg horse 225 mg hen 215 mg L ) (Georgievskii et al. 1982). 

J. L. Burguera, M. Burguera, and M. Gallignani, Direct Determination of Sodium and Potassium in Blood Serum by Flow Injection and Atomic Absorption Spectrophotometry. An. Acad. Bras. Cienc., 55 (1983) 209. 

Fluorescent Chemosensors for Monitoring Potassium in Blood and across Biological Membranes... 

Documented effects In experiments on animals, the total saponins isolated from the roots and the preparation Zongorozid caused a significant decrease in arterial pressure, increased resistance to hypoxia, and had sedative effects. In experiments with dogs, the preparation Zongorozid increased the sodium in erythrocytes and reduced potassium in blood plasma as well as in erythrocytes. A one time dose of the preparation has blood coagulating effects but multiple applications, over 5-7 days, have better effects. The effects include an increase in tolerance to heparin, reduction of prothrombin time and fibrinolytic activity, increase in fibrinogen content (up to 45 %), and an iuCTease of the adhesion index with an increase in blood coagulation potential (Alimbaeva et al. 1986). 

Additive pharmacodynamic effects. In the case when two or more drags exhibit similar pharmacodynamic effects it may produce an excessive manifestation of toxicity. It could be compounds whose combination may cause QT interval prolongation, leading to ventricular arrhythmia, as well as compounds that increase the concentration of potassium in blood and lead to hyperkalemia. An additive pharmacodynamic effect is also used for therapeutic purposes, so diuretics and angiotensin-converting enzyme inhibitors cause the blood pressure reduction... 

Osswald, E. E, Continuous determination of potassium in blood, Clin. Chem., 25, 32, 1979. 

Of all the types of glass membrane electrodes on the market, the sodium-selective electrode is the most widely used for direct sodium activity determinations. These measurements are as straightforward as pH measurements, since, except for the Ag" ion, all other species present in the test solution can be ignored. The cation-sensitive electrode is much less suitable for potassium ion determinations, although it has been used in the past only for lack of a better alternative. Friedman et al. [82] reports a simultaneous determination of both sodium and potassium in blood and plasma samples with the help of both types of electrodes. Here a computer was employed to... 

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