Metabolism of fructose in the small intestine II. The effect of fructose feeding on fructose transport and metabolism in guinea pig small intestine

Abstract

1. The metabolism and transport of fructose in guinea pig small intestine following fructose feeding for up to 20 days has been measured. A preparation of villus epithelial cells was used for the measurements. 2. In confirmation of the results of other workers, most of the fructose metabolized by guinea pig small intestine appears as glucose, the rest appearing as lactate. 3. Fructose feeding had no effect on the protein content of the epithelial cell preparation, however, the DNA content decreased markedly after 10 days on the fructose diet. 4. Fructose metabolism decreased initially on fructose feeding. Subsequently a gradual increase occurred which became very pronounced after 10 days on the fructose diet. 5. Fructose feeding for 3 days resulted in no change in the activities of fructo-kinase and fructose-1-phosphate aldolase in the guinea pig small intestine. 6. Measurements of the rate of fructose uptake in segments of intestine taken from guinea pigs fed on normal laboratory chow or the fructose diet were made. The rate of fructose uptake in segments of intestine taken from animals fed for 3 days was the same as that of animals fed on normal laboratory chow. There was a slight increase in the rate of fructose uptake in intestinal segments taken from animals fed the fructose diet for 20 days. 7. Histological section of intestine taken from animals fed the fructose diet for 20 days showed an accumulation of a yellowish material in the sub-epithelial region at the tips of the villi. This material appeared to be present within macrophages. Preliminary evidence indicates that the material is a protein containing a carbohydrate component.