Ultrastructural and biochemical studies on the intestinal absorption of a medium-chain triglyceride (MCT), tricaprylin

The intestinal absorption of a medium-chain triglyceride (MCT) was studied by electron microscopy and biochemical analysis. In jejunal absorptive cells of rats fed tricaprylin, the smooth endoplasmic reticulum in the apical cytoplasm appeared to increase in number and contained one or two particles about 40-80 nm in diameter that were less electron dense and similar in size and profile to very low density lipoprotein. Similar particles were also observed packed in the dilated Golgi sacs and in the extended intercellular spaces. These particles were remarkably increased in number as compared with those in fasted rats. Biochemical analysis of lymph from the main intestinal lymph duct showed that caprylate was apparently demonstrated only in the lymph of rats given tricaprylin at the maximum rate 3 h after oral administration. The study strongly suggests that medium-chain triglyceride is at least in part transported via lacteal, possibly in the form of very low density lipoprotein. © The Clinical Electron Microscopy Society of Japan 1998.