The metabolism of the erythrocyte. XIX. Factors affecting esterification of linoleate by human erythrocytes

Abstract

Factors affecting the esterification in vitro of linoleate-1-14C by intact human erythrocytes were investigated. Lecithin contained the highest proportion of the esterified fatty acid, but it was not possible to detect any incorporation into the neutral lipids. Glucose caused a slight increase in incorporation into erythrocytes which had been stored for 18 h at 4°, but had little effect on fresh cells. Esterification was proportional to the intracellular nucleotide labile phosphate level (corresponding to the ATP and ADP levels), provided the latter was less than that found in fresh erythrocytes. However, no further increase in esterification occurred when the level of nucleotide labile phosphate was raised to twice that of fresh cells by incubation for 10 h with glucose and adenine. Water-immiscible phthalate esters, used for the separation of young and old erythrocytes, increased esterification two- to three-fold without altering either its correlation with the intracellular nucleotide labile phosphate level or the distribution of the linoleate-1-14C among the various phospholipids. The oldest 5% of the cell population, whether separated by phthalate esters or in Ringer solution, showed a diminished level of nucleotide labile phosphate and a decreased rate of esterification. The presence of glucose restored the level of linoleate-1-14C incorporation by old cells to that of the remainder of the cell population. Lysolecithin increased the rate of esterification without altering the distribution of the linoleate-14C among the phospholipids, and removed the difference between normal and energy-poor cells. These data suggest that the rate-limiting step in esterification may involve an energy-sensitive transport of free fatty acids into an intracellular precursor pool rather than the fatty acid esterification (thiokinase) reaction.

Effect of dietary di‐2‐ethylhexyl phthalate on oxidation of14C‐palmitoyl CoA by mitochondria from mammalian heart and liver

“…The data presented here re-emphasize the fact that phthalate esters, commonly used as plasticizers, are biologically active and capable of modifying lipid metabolism in mammalian systems (4)(5)(6)(7)(8)26). The association of phthalate esters with toxicity effects in components of the blood and cardiovascular systems (14,(25)(26)(27)(28)(29)(30) is of particular importance since patients receiving medical treatment with products stored in PVC (polyvinylchloride) plastic containers or PVC plastic delivery devices can be exposed to (10,14,(31)(32)(33)(34), and accumulate phthalates such as DEHP in blood, lung, and myocardium ( 10,14).…”

Esterification of Linoleate by Rabbit Reticulocytes

“…The data in Table 3 also show that the incorporation of linoleate into reticulocyte lipids was not affected by the elevated levels of ATP. This resembles the picture previously reported for mature erythrocytes (12). In several experiments the level of ATP was lowered to approximately that seen in normocytes by incubation of the reticulocytes without glucose for 4 h. However, there was no significant decrease in the rate of linoleate incorporation (' Table 3).…”

“…When erythrocytes were incubated with lower concentrations of linoleate such as those used by Shastri and Rubinstin (12) Iysolesithin was found to increase esterifieation. This may be due to alteration s f the membrane by %ysolwithh, allowing penetration' of fatty acids at lower conextratiom.…”

Effects of Dietary Fat on Lipid Composition of Serum and Erythrocytes of the Swine and in Vitro Incorporation of Fatty Acids Into Erythrocyte Membranes

“…OLIVEIRA and VAUGHAN (7) and Van DEENEN and coworkers (8,9) noted the incorporation of 14C-labeled fatty acids into washed erythrocyte ghosts in the presence of ATP, CoA and MgCl2. MULDER et al reported an influence of dietary fat (10) on the incorporation of fatty acids into animal erythrocytes and other investigators (11,12) on the im portance of cofactors and nutrients in this phenomenon. This report describes a study of the effect of dietary fat on the lipid composition of sera and erythrocyte in the swine, and the incorporation and release of fatty acids in vitro.…”