Abstract

From a bone gelatin, average molecular weight 50,000, fractions were prepared with average molecular weights of 29,000, 36,000, and 69,000 by alcoholic precipitation. Solutions of these gelatines isoösmotic with dog blood plasma were injected intravenously in normal anesthetized dogs, in a volume of 25 cc. per kilogram, or an average of 63% of the control plasma volume. Retention of gelatin and of fluid in the circulation over a 4-hour period varied directly, but not proportionally, with the molecular weight. Retention does not increase markedly with increase in molecular weight above 50,000. By extrapolation, a fraction of this gelatin with average molecular weight of 25,000 or less can be expected to show little retention.

The fraction of injected gelatin excreted in the urine in 4 hours varies inversely with the molecular weight.

No reduction in total circulating plasma protein followed the injection of gelatin, except in one experiment with the high-molecular weight fraction.

None of the gelatin fractions reduced the amount of total circulating hemoglobin. All of the gelatin fractions caused some shrinkage of erythrocytes.

Sedimentation of erythrocytes was increased by all gelatin fractions, most extensively by the high-molecular weight fraction.

One animal succumbed following the injection of high-molecular weight gelatin.