[Electron microscopic study of 3H-leucine transport between the internal body environment and the enteral environment].

Using electron microscopic autoradiography, a space-time characteristics of 3H-leucine transport, from the enteral to the inner environment, and from blood plasma to the enteral environment, has been given. Some gradient of intracellular leucin accumulation is determined, from the tip cells of a villus to epithelocytes of the basal membrane. Amino acid transport from blood plasma to the lumen of the intestine is accomplished mainly via the cytoplasm and intercellular space of epithelocytes of the villus basement.

[Role of the enterohepatic circulation of endogenous lipids in food lipid absorption].

In preliminarily operated dogs with fistulas in stomach and different portions of the small intestine, the liver-intestinal circulation of endogenous phospholipids and cholesterine aided to form the chimus all the lipid fractions of which were absorbed proportionally. The recirculation of endogenous lipids seems to be one of the physiological mechanisms of lipid absorption from food in the small intestine.

[Homeostatic influence of the lipid composition of the chyme and the effect of the correlation of basic lipid classes on the intensity of their absorption in the small intestine].

Experiments on normal unanesthetized polyfistulous dogs kept on a mixed diet were made to study the basal lipid ratios of the duodenal and small intestinal chyme. It was shown that the duodenal and small intestinal chyme underwent homeostasis as regards the basal lipid class at the expense of the adding endogenous lipids to digestive juices. The ratios mentioned did not change substantially as a result of lipid absorption during exposure of the chyme in an isolated part of the intestine.

[So-called constancy of chyme composition].

Study of the chyme composition in different phases of digestion at different levels of the small intestine showed the composition to be stabilized enough in respect to the water and electrolytes contents as well as the main nutricious substances. Gradual increase in concentration of the main NSs occurs in the advancing chyme. The data obtained suggest that the constancy of the chyme composition is only valid in respect to the water and electrolytes regardless of their unequal contents in the food.

[Participation of the small intestine in intermediary lipid metabolism].

Data obtained in preliminarily operated healthy animals with the aid of a single or repeated lipid load achieved by means of heptadecan acid, showed that the C17:0 acid becomes involved in processes of lipid synthesis in the intestine epithelium, absorbed in the gastro-intestinal tract, and spread by the blood over different tissues, including the isolated loop of small intestine, in the form of various complex lipids. The small intestine appears to be a depot of lipids accumulating products which can be reabsorbed from the intestine lumen. As the depot reguires no hormonal or enzymatic mechanisms for mobilizing the resources, it has its advantages and is rather mobile.