Lipid metabolism in helminth parasites—V. Absorption of fatty acids and monoglycerides from micellar solution by Hymenolepis diminuta (cestoda)

Abstract

1. 1. Hymenolepis diminuta readily absorbed oleic acid, linoleic acid and 1-monoolein through its integument when these were dissolved in sodium taurocholate micelles. 1-monostearin, which is only sparingly soluble in micelles, was not as readily absorbed. Sonicates or emulsions of these compounds, or of triglycerides, were absorbed very poorly at physiological pH. 2. 2. Monoglycerides were almost completely hydrolyzed following absorption. The concentration of lipase in isolated H. diminuta integument was sufficiently high to account for this hydrolysis. 3. 3. Glycerol and fatty acid label from absorbed and hydrolyzed monoolein was rapidly incorporated into H. diminuta neutral glycerides and less rapidly into polar lipids. Excretion of free fatty acids from the tapeworm occurred at the same time. Fatty acid label from absorbed and hydrolyzed monostearin was not readily incorporated into the tissue glycerides. 4. 4. The results support a previously stated hypothesis in that they illustrate the advanced degree to which H. diminuta has adapted to life in the rat small intestine by becoming almost wholly dependent upon an exogenous supply of fatty acids. They also suggest that the high content of unsaturated acids in the tapeworm tissues is directly related to the relatively high solubility of such acids or monoglycerides in bile sale micelles, to their relatively high rate of absorption and to the ease with which they are acylated by H. diminuta enzymes.