M. L. Blank

Molecular species of ethanolamine plasmalogens and transacylase activity in rat tissues are altered by fish oil diets

Effects of dietary fish oil ethyl esters and alkyldiacetylglycerols (an ether-linked lipid) on the distribution of subclasses of choline- and ethanolamine-glycerophospholipids as well as effects on highly unsaturated molecular species of ethanolamine plasmalogens from brain, spleen, kidney, lung, and testis of rats were examined. Supplementation of ethyl ester concentrates of n-3 fatty acids had no effect on the distribution of subclasses in any of the tissues. However, the supplements of 1-O-octadec-9-enyl-2,3-diacetyl-sn-glycerol (diacetates of selachyl alcohol) caused significant increases in the alkylacylglycerophosphocholine and alkylacylglycerophosphoethanolamine subclasses from spleen and lung and in the alkylacylglycerophosphoethanolamine subclass from kidney. Dietary supplements of fish oil ethyl esters reduced the arachidonate-containing species of ethanolamine plasmalogens whereas molecular species having 20:5(n-3), 22:6(n-3), and/or 22:5(n-3) acyl groups were increased in the spleen, lung, and kidneys, but not brain. In testicular tissue from rats fed the fish oil diets, the molecular species of ethanolamine plasmalogens containing 22:5(n-6) acyl groups were reduced. An increase of ethanolamine plasmalogens with 18:1 alk-1-enyl moieties paired with highly unsaturated sn-2 acyl groups were found in the tissues of rats fed the fish oil plus selachyl alcohol diacetate supplements. Rats on the diet containing fish oil ethyl esters had significantly lower [3H]alkyllysoglycerophosphocholine CoA-independent transacylase activity in spleen microsomes than controls. This suggests that supplements of n-3 fatty acids interferes with the transacylation of arachidonate, an event that could seriously impair the release of arachidonate and lysophospholipids (e.g., lyso-PAF) that are precursors of potent bioactive lipid derivatives.

Evidence for biosynthesis of plasmenylcholine from plasmenylethanolamine in HL-60 cells.

Both [3H]plasmenylethanolamine and [3H]plasmenylcholine were produced from substrates of [3H]alk-1-enylglycerol and [3H]alk-1-enyllysoglycerophosphoethanolamine by intact HL-60 cells. Molecular species analysis of the [3H]plasmenylcholine and [3H]plasmenylethanolamine formed indicated the major portion of plasmenylcholine originates from plasmenylethanolamine by a series of reactions catalyzed by phospholipase A2, lysophospholipase D, acyltransferase, phosphohydrolase, and cholinephosphotransferase. However, a significant but much smaller portion of the plasmenylcholine appeared to be synthesized from plasmenylethanolamine via a direct base-exchange or a coupled phospholipase C/cholinephosphotransferase reaction.

Liposomal encapsulated Zn-DTPA for removing intracellular 169Yb.

Abstract— Multilamellar liposomes possessing neutral, positive or negative charges were tested for their capacity to encapsulate sodium ethylenediaminetetraacetate (EDTA) and for their selectivity in depositing in specific tissues after being injected into rats. Negative‐charged liposomes had the greatest trapping efficiency over a wide range of lipid‐to‐aqueous phase ratios. In contrast, except for lung, liposomal charge had no significant effect on the tissue distribution of encapsulated EDTA; liver and spleen exhibited the highest uptake with all preparations. The proportion of encapsulated EDTA taken up by the liver decreased as the amount of injected liposomes was increased. Free zinc diethylenetriaminepentaacetate (Zn‐DTPA) and multilamellar liposomes containing entrapped Zn‐DTPA were administered to rats that had been injected with 169Yb‐citrate 24 hr earlier. At doses of 14 mg Zn‐DTPA per kg body weight, both free Zn‐DTPA and the liposomal‐bound Zn‐DTPA caused increased removal of 169Yb from the animals. However, treatment with the liposomal Zn‐DTPA caused significantly more of the 169Yb to be removed than did the free Zn‐DTPA treatment by itself. Our data indicate that lipophilic forms of chelators can effectively increase the removal rates of heavy metal contamination in tissues.