Plasma phosphatides

M. Albrecht, T. Ford, and E. Stotz Analysis of human plasma phosphatides by paper chromatography. Biochem. biophys. Acta (Amst.) 36, 4 (1959). 

N. Rate of Interchan of Plasma Phosphatides with Tissue Phospha-... 

Friedlander and colleagues (58) observed furthermore that the additional amounts of radiophosphatides formed under the influence of choline do not long remain in the liver. They pass into the plasma and increase the specific activity of plasma phosphatides. A single feeding of 300 mg. choline chloride per kg. of body weight increases markedly the phosphatide turnover in the plasma, as seen in Figure 8. While after 12 hours the effect of choline is most pronounced, after the lapse of 96 hours the specific activity of the plasma phosphatides shows almost the same value as found in the controls. 

Fig. 8. Elffect of choline on the specific activity - time relations of plasma phosphatide phosphorus in a dog (58).

If the phosphatide molecules of carcinomatous tissue were replaced at a high rate by labeled molecules, and such molecules were given off by the tumor to the circulation shortly after the administration of labeled phosphate, the presence of carcinomatous tissue could possibly be diagnosed by determination of the activity of plasma phosphatides. The facts, however, that the phosphatide turnover of neoplastic tissue is much slower than turnover in liver and intestinal mucosa and that phosphatide molecules in the circulation were to a very large extent built up in the liver frustrate this possibility. 

N. RATE OF INTERCHANGE OF PLASMA PHOSPHATIDES WITH TISSUE... 

As mentioned above, in the course of few hours a very appreciable part of the phosphatide molecules originally present in the plasma are found to be replaced mainly by phosphatide molecules previously present in the liver. Reinhardt et al. (146) found that part of the labeled phosphatide molecules injected into plasma reached lymphatic channels and were recovered in the thoracic duct lymph. It is not established through which tissues phosphatides migrate, although liver presumably plays an important part in this process. Some figures for the recovery of injected labeled plasma phosphatides are seen in Table XXIV. 

Ovary phospliatides are only. slightly active plasma phosphatides show a marked activity and liver phosphatides show the greatest activity. 

Strong additional evidence that plasma phosphatides, which in turn supply yolk phosphatides, are mainly derived from liver, is provided in investigations on formation of labeled phosphatides in the hepatectomized... 

At all intervals the highest values for deuterium content were observed in liver phosphatides. The smallest incorporation of deuterium was observed in brain phosphatides, and thus the result obtained was similar to results of the incorporation of into phosphatides of different organs. The observation that plasma phosphatides have lower deuterium values than liver at the end of six hours was interpreted as suggesting incorporation of deuterated fatty acids into liver phosphatide. A similar conclusion was drawn concerning incorporation of phosphate into the phosphatide molecule (see page 156). 

Administered elaidic acid was found by Sinclair (166) to appear early in plasma phosphatides of the cat. A rapid replacement of phosphatide fatty acids of plasma is indicated by the observation that, eight hours after the feeding of elaidic acid, about 20% of the plasma phosphatide fatty acids consisted of this acid. Maximum incorporation after feeding occurs in less than one day in small intestine and in slightly more than one day in liver. In kidney and muscles, one-half of the maximum incorporation occurs in about three days. The rate of entry of elaidic acid into phosphatides of carcinosarcoma 256 is slower than into liver phosphatides but faster than entry into muscle phosphatide (73), a behavior also shown by labeled phosphate. 

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