Anticoagulating Substances

ANTICOAGULATING SUBSTANCES. Anticoagulation is the phenomenon of delaying or eliminating the coagulability of a colloid (see). In the physicochemical sense, this phenomenon consists of the colloid, under the influence of anticoagulating substances, acquiring the ability to keep its particles in a state of fine dispersion in a liquid. If the degree of dispersion of colloidal particles depends on their electric charge, then anticoagulation can be achieved by adding appropriate electrolyte salts, the ions of which are adsorbed by the colloidal particles, strengthening their electric charge and thereby keeping them from precipitating, from coagulation. The same can be achieved by recharging the colloid particles by adding an excess of another colloidal solution carrying an electric charge of the opposite sign on its particles. In some colloids, for example, hydrophilic colloids of the protein type, the particles are maintained in a suspended state due to the water "shell" surrounding all such particles. Anticoagulating substances are of particularly great importance in the field of hematology. Processes that delay blood clotting can be fundamentally different; thus, the clotting-preventing, stabilizing property of sodium salts of oxalic, hydrofluoric, and citric acids depends on the binding of blood calcium ions, which are necessary for the formation of thrombin. It is possible that this also applies to sodium salts of fatty acids (soaps). Conversely, peptones, albumoses, and hirudin are antithrombins and cause anticoagulation by participating in the phase of thrombin's action on fibrinogen. The serum of syphilitics possesses the property of binding substances of the thrombokinase type. Finally, sodium chloride, calcium, and magnesium sulfate, when used in known concentrations, stabilize blood by changing the conditions of the medium, but do not bind the components on which blood clotting depends. The action of many other substances that cause blood anticoagulation has not been sufficiently studied (glucose, arsenobenzene, heparin, trypsin, cobra venom, etc.). Blood stabilization has found wide application in the field of medicine, physiology, and biochemistry for blood transfusion, the study of morphological, chemical, and physical properties of blood (blood platelets, enzymes, viscosity), in the study of the dynamics of blood circulation, and many others. Stabilization of 100 cubic centimeters of blood in vitro is achieved by using the following doses: Sodium citrate 0.2–0.4; Sodium oxalate 0.1; Hirudin (Jacobi) 0.016–0.02; Novirudin (O. Adler and W. Wiechowski) 0.1; Germanin (Steppun, Zeiss, and Bryukhonenko) 0.2–0.4. Blood stabilization in vivo is carried out by intravenous administration of such doses (per kilogram of animal weight): Hirudin 0.0285–0.054; Novirudin 0.075; Germanin ("Bayer 205") 0.3 (Steppun, Zeiss, and Bryukhonenko). Theoretical research in the field of anticoagulation has linked the processes of protein anticoagulation (when heated to 100°) and the processes of blood non-coagulability. Three groups of chemical substances have been found that deprive protein (serum) of the ability to coagulate when heated over an open flame. The first group: sodium (K, Li) salts of a whole series of weak organic acids—salicylic (10–15%), benzoic (20–33%), oleic and stearic (0.5%), glycocholic, and many others. The second group: substances of the urea, cyanamide, pyridine type. The third group: substances of the glucose, cane sugar (but not milk sugar) type, glycerin, glycol; ethyl alcohol (20–30%). Many of the anticoagulating substances of these three groups also stabilize blood.