Swelling of Gelatin in a Series of Human Blood Sera

Abstract

During the past thirty-five years, there has been considerable speculation as to the rôle played in pathology by abnormal increases and decreases in the state of swelling or water holding power of tissues. 1

The resultant swelling tendency exerted upon tissue by plasma, or the lymph derived therefrom, is necessarily a function of the concentrations of a number of the plasma constituents. The writers believed that it would be desirable to have some single test available for this resultant tendency, and that such a test might be afforded by observation of the effect of plasma or serum upon some standard swelling material such as gelatin.

Small squares of Eastman Kodak Company's “ash-free” gelatin, weighing about .05 gm., were placed in Ringer-Tyrode solution (glucose omitted) and allowed to swell for 40 hours at about 10° C. The solution contained sodium bicarbonate, and was kept in contact with alveolar air. The pH was maintained within the range pH 7.2-pH 7.6. The percentage swelling of the squares was determined from a comparison of their swollen and original dry weights. It was of the order of 11 times in all cases, and, in any one series, the maximum difference between values was about 2 parts per hundred.

Blocks of gelatin were thus provided in a standard state of swelling. It was hoped that this state would be such that the blocks would swell further in some sera and shrink in others. This proved to be the case.

In a series of 22 normal and pathological sera, the one showing the greatest swelling tendency caused a standard block to swell 5.1% further, and the one showing the least swelling tendency caused a 1.2% shrinkage. A standard block, as described above, was immersed in each serum for 20 hours in the ice chest, after which any change in weight was noted. The pH of each serum was adjusted by saturation with alveolar air and controlled between the limits pH 7.2-pH 7.8 throughout. Duplicate experiments indicated an unavoidable experimental variation of less than one percent.

The foregoing results indicated that, in a series of sera, the resultant swelling tendencies with regard to standard gelatin blocks may be measured and clearly differentiated. It next became of interest to determine the composition variable or variables primarily responsible for the swelling variations observed.