Oral Fructose Tolerance, Gastric Emptying and Absorption: A Compartmental Model bY

Abstract

Gastric emptying and intestinal absorption regulate transfer of ingested fructose from stomach to plasma. Using conscious rhesus monkeys we have developed a compartmental model which describes this system. Fructose tolerance tests were performed in groups of monkeys by intragastrically administering 2 g/kg of 10.5% D-fructose solution; fructose concentration in arterial plasma, [fructose], and intragastric volume were measured at intervals afterward. One group was pretreated with atropine; stomachs emptied with a time constant, τ, of 67 min. Another group received fructose solution with trisodium citrate added; τ was 18 min. Another group received only fructose; τ was 30 min. Using these constants, a model was developed to describe the [fructose] data. In this model k₁ related amount of fructose in intestine to absorption rate and A_e represented absorption efficiency. k_x = 0.03 and A_e = 89% provided a good fit for data from the atro-pinized group. k_x = 0.018 and A_e = 56% provided a good fit for data from the other groups. Differences were explained by considering effects of atropine on gastrointestinal secretion. The model adequately describes our [fructose] data and may be adapted for tests utilizing other substances.

In conducting the research described in this report, the investigators adhered to the Guide for the Care and Use of Laboratory Animals, as promulgated by the Committee on Revision of the Guide for Laboratory Animal Facilities and Care of the Institute of Laboratory Animal Resources, National Research Council. The facilities are fully accredited by the American Association of Accreditation of Laboratory Animal Care.