Intestinal Cell Respiration Is Influenced by Animal Age, Strain, and Feeding Status

Abstract

The objectives of this study were to evaluate the influence of aging and the fasted vs fed state on substrate oxidation by jejunal and colonic cells in vitro, and to determine whether the effects of these factors would be influenced by rat strain. Young (4 mo) and aged (24 mo) male rats of the Fischer 344 (F344) and Fischer x Brown Norway (F x BN) strains were used either following a 48-hr fast or in the ad libitum fed state. On the morning of experimentation, cells were removed from segments of the jejunum and colon and aliquots of these suspensions were incubated in 5 mM concentrations of substrates containing trace quantities of 14C-labeled isotopes. Following 60 min of incubation, 14CO2 was collected and quantified to determine substrate oxidation. The oxidation of glucose, glutamine, and 3-hydroxybutyrate was studied in jejunal and colonic cells, and the oxidation of acetate and butyrate was studied in colonic cells only. Glucose oxidation by jejunal cells was lower when cells were taken from 48-hr fasted animals than from fed animals, but the feeding status of the animal did not significantly influence oxidation of other substrates by jejunal or colonic cells. Substrate oxidation was not different for the F344 vs F x BN strains when jejunal and colonic cells were taken from young animals. Differences due to rat strain became apparent in the aged animals, however, with oxidation of several substrates being higher for the aged F344 than for the aged F x BN animals.(ABSTRACT TRUNCATED AT 250 WORDS)