Pathological Changes in the Viscosity of Blood Serum.

Abstract

Measurements of the viscosity of blood serum reported by clinical observers have shown results that are seemingly paradoxical. We have attempted to investigate the physical-chemical basis of these empirical relationships.

Blood serum, as seen from the viscosity at different dilutions, shows a remarkable ability to keep its viscosity constant in spite of dilution. If we compare the effects of dilution on the viscosity of such a protein as gelatine, we find that not alone is the absolute viscosity of the same percentage concentration of serum protein very much lower than that of a similar strength of gelatin, but the gelatin manifests a much greater change in viscosity for each increasing unit of dilution. The importance of this point in maintaining the circulation of the blood in such conditions as nephrosis, where the blood proteins are reduced to one half their normal concentration, is obvious.

Loeb has distinguished between two types of protein, one represented by gelatin and the other by egg albumin. In the former there is an enormous tendency toward the formation of submicroscopic particles of solid gelatin which, as a result of the inability of the protein ion to freely diffuse, set up a Donnan equilibrium with the result that water is occluded and these particles increase in size. On the other hand, we have such proteins as albumin, which show no tendency at a pH in the neighborhood of neutrality and at body temperature toward the formation of these submicroscopic particles. These show a low viscosity and no tendency to jell. There are certain exudates, especially pleural exudates, which after standing become jellified. If Loeb's hypothesis were correct, these exudates should show a higher viscosity than other exudates and transudates that do not jell.