Abstract
During studies on clearance of intravenously administered fat emulsions, chemically direct measurements were made of the tri-di-, and monoglyceride content of washed red blood cells. Because of some unusual and interesting observations, it was believed desirable to repcrt the results of these studies
Methods. Plasma was separated from the cells of heparinized whole blood samples in a 5°C refrigerated centrifuge. The cells were washed with an equal volume of 0.9% NaCl solution, recentrifuged at 2260 g for 30 minutes, and the liquid decanted. The buffy coat was discarded and the red cells were washed 3 more times as above. The washed red cells were then hemolyzed in 2 volumes of distilled water with mechanical agitation. When complete hemolysis had occurred, 1 ml portions were immediately placed into appropriate extraction solutions (chloroform : zeolite for glycerides; heptane : isopropanol : sulfuric acid for ncm-esterified fatty acids or NEFA). Tri-, di-, and monoglycerides were separated an small silicic acid columns; after alkaline hydrolysis and periodate oxidation. the glycerides were measured by the color developed with chromotropic acid (1) . NEFA was determined by the method of Dde(2); lactic acid and acidic phospholipids are possibly in cluded in this fraction(3).
Results and discussion. Tri-, di-, monoglyceride, and NEFA levels of human and canine red blood cells are given in Table 1. Whereas in cells of both species the content of tri- and monoglycerides is similar, the dog cells have considerably more diglyceride and less NEFA than human red cells. In plasma of dogs fasted 20 hours total glyceride level matches that of the cells (Fig. 1); however, 75% is triglyceride and proportionately much less di- and monoglyceride occurs in the plasma than in the red cells. Human males fasted for 12 hours had twice as much total glyceride in blood serum as in red cells. Since the cell and serum contents of mono- and diglycerides are similar, it appears that almost 4 times as much triglyceride occurs in a given volume of fasting blood serum as in the red cells of humans.
Amounts of glycerides and NEFA in red blood cells fluctuate within the limits indicated by the standard deviations shown in Table 1. These are relatively fixed levels and are not influenced by great elevation in fat content of the plasma. Thus, in humans 4 hours after meals containing 50 and 100 g of corn oil or cocoanut oil and also in dogs 8 to 30 minutes after being given intravenous fat emulsion, the washed red blood cell glycerides and NEFA were not significantly different from those in the fasting state.
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