The Extraction of Lipids from the Red Blood Cells*

In a previous communication (1) it has been shown that lipids may be completely extracted from blood plasma or serum without heat if diluted with 20 volumes or more of alcohol-ether. The maximum cold extraction of whole blood was found to require at least 30 volumes of solvent. No values for the red blood cells were reported at that time, because it was found that heat produced apparently higher values after maximum extraction had been obtained in the cold. A similar situation prevailed in extracts of whole blood. Since heating caused the extraction of colored products from the decomposition of hemoglobin, products which were not present in cold extracts and which contaminated all of the isolated lipids, it was unknown whether the apparently higher lipid values in the heated extracts were due to further extraction of lipids or only to the presence of the contaminating colored material. There having since been found a satisfactory method of separating this colored matter from the lipids, the present report is concerned with the optimum conditions for extracting lipids from the red blood cells, in general according to the same procedures previously used with plasma and serum. There have been two common methods for estimating the lipid composition of the red blood cells, the direct and the indirect. In the first the red cells are isolated and an extract made of the weighed or measured cells either with or without saline washing. In the second, the lipid content of whole blood and of plasma is separately estimated and values for the red cells are calculated