Excretion from the gut and gastrointestinal exchange

Summary Intake-excretion studies supply inadequate information about absorption and exchange of such readily exchangeable substances as cholesterol. An inert indicator method applies a modification of the well-known Fick principle to the study of excretion in the stools. Excretion in the stools of the stable compound and excretion of the portion unabsorbed of the corresponding isotopically labeled compound that had been added to the food can be determined nearly simultaneously. From these data complete information about exchange, including quantity of substance secreted into the intestine and the total amount absorbed, can be calculated. In order to take into consideration alterations of the material while in the lumen of the gut, or to prevent conversion to other substances, the qualitative aspects of the metabolism of the compound must be known. As an example, the gastrointestinal exchange of cholesterol is described in detail.Presented in part at the joint meeting of the Subsection on Gastroenterology, American Federation for Clinical Research and the Gastroenterology Research Group, Atlantic City, N. J., April 29, 1956.This investigation was supported in part by research grant A-463C from the National Institute of Arthritis and Metabolic Diseases of the National Institute of Health, Public Health Service, and in part by grants from the Massachusetts Heart Association, the American Cancer Society (Massachusetts Division), Inc., and the Charlton Fund of Tufts University School of Medicine.