title: Changes in metabolite transport by small intestine and kidney of young and old rats.
abstract: We have studied the influence of the ageing phenomenon on metabolite absorption by the small intestine and the kidney of the rat, using isolated brush-border membrane vesicles prepared from 2 groups, one composed of 2 month, and the other of 24 month, animals. "Overshoot", which is typical of Na(+)-glucose cotransporter activity, disappeared in the duodenum and decreased in the kidney of the old rats. Short-circuiting of vesicles with valinomycin showed that, in the presence of K+ and valinomycin, "overshoot" decreased in both groups by about the same percentage. The Na(+)-dependent uptake of aspartate and phenylalanine showed contrasting pictures in the jejunum and kidney of the aged animals: aspartate transport decreased only in the kidney, while phenylalanine uptake was negatively affected in the jejunum. Na(+)-dependent citrate uptake, studied in renal brush-border membrane vesicles, was lower in the old rats. The Km values determined for Na(+)-dependent D-glucose and citrate uptake in the kidney did not meaningfully differ between the two groups. A continuous decrease in Na(+)-dependent D-glucose and citrate uptake in the rat kidney, during ageing, was demonstrated.
authors.affiliation: Department of Biochemical Sciences, University of Florence, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Treves
authors.forename: F
authors.initials: F
authors.lastname: Favilli
authors.forename: M
authors.initials: M
authors.lastname: Stio
authors.forename: T
authors.initials: T
authors.lastname: Iantomasi
authors.forename: M T
authors.initials: MT
authors.lastname: Vincenzini
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001224:Aspartic Acid / Q000493:pharmacokinetics*; D002951:Citrates / Q000493:pharmacokinetics; D019343:Citric Acid; D005947:Glucose / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000254:growth & development / Q000378:metabolism*; D007672:Kidney Cortex / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D008871:Microvilli; D010649:Phenylalanine / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002951:Citrates; D019343:Citric Acid; D001224:Aspartic Acid; D010649:Phenylalanine; D005947:Glucose