Phosphatide extraction from liver

The specific activity of phosphatides extracted from rabbit and rat kidney is lower than that of phosphatides from small intestine and liver at early intervals after administration of radioactive phosphate. After the lapse of six hours the same result was obtained in experiments with dogs, but after eighteen hours the specific activity of the kidney phosphatide remained lower than that of liver and about equal to that of small intestine. At 98 hours the specific activities of the phosphatides in all three tissues wore roughly the same (32). Acidosis induced by ingestion of ammonium chloride increases turnover of kidney phosphatides, according to Weiss-berger (181). Administration of phlorizin did not influence turnover rate of phospatides in kidneys of the rat (182). 

Extraction of Phosphatides from Liver. The weighed tissue was ground with sand in a mortar, transferred to a flask, and extracted with alcohol at 55-60 C. for two hours with occasional shaking. Approximately 150 cc. of alcohol were used for 20-25 g. of liver. The supernatant alcohol was decanted through filter paper and the residue extracted with a second portion of alcohol for one hour. The contents of the flask were then poured through the same filter paper and the two alcohol extracts were combined. The tissue residue was then extracted overnight with ether in a Soxhlet apparatus and the ether extract was added to the alcohol extracts. The combined alcohol-ether extracts were concentrated to a small volume (3-4 ml.). This was carried out in a hot water bath (55-60 °) under reduced pressure and in an atmosphere of carbon dioxide. This concentrate was extracted with several portions of petroleum ether (b.p. 30-60 ) and the petroleum ether extract made up to a desired volume by the addition of more petroleum ether. 

In connection with the above consideration, it is of interest to consider some results obtained by Cavanagh and Raper (31). They found that the glycerides extracted from the plasma of rats six hours after feeding of deuterium-containing linseed oil contained ten times as much deuterium (in atoms per cent) as the phosphatides of the plasma. This result is understandable if most of the phosphatide molecules present in the plasma have been synthesized in the liver and not taken up from the intestine. 

Labeled sodium phosphate was administered to laying hens, the eggs laid were collected, and the specific activitie.s of tlie phosphatide phosphorus extracted from the yolks were determined. In other experiments, the hen was killed and the specific activities of the phosphatide phosphorus of the yolks, ovary, liver, intestinal mucosa, and plasma were compared. The following figures show the results obtained for the specific activity of phosphatide phosphorus extracted from different organs of a hen 6 hours after administration of labeled sodium phosphate (85) ... 

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