title: Effect of feeding on glomerular filtration rate and proteinuria in conscious aging rats.
abstract: Food intake increases glomerular filtration and proteinuria in adult rats. That this postprandial hyperfiltration could be age dependent was investigated in 3-, 10-, 20-, and 30-mo-old rats. Glomerular filtration rate and protein excretion were measured in fed or 24 h fasted conscious animals. In the 3-mo-old rats food ingestion increased renal filtration by 45% from 1.17 +/- 0.08 to 1.73 +/- 0.11 ml.min-1.g kidney wt-1 (n = 6). As the animals became older, the differences between fed and fasted periods became smaller: in 30-mo-old rats glomerular filtration rate was 0.85 +/- 0.03 and 1.01 +/- 0.06 ml.min-1.g kidney wt-1 (n = 6) in fasted and fed conditions, respectively. Proteinuria, which was mainly albuminuria, increased slightly with age and was more markedly reduced by acute food restriction in the 30-mo-old than in the 3-mo-old rats. Because the renin-angiotensin system activity decreases with age, its role in postprandial hyperfiltration was assessed by measuring glomerular filtration in 3-mo-old animals whose angiotensin II converting-enzyme activity was chronically inhibited by daily administration of perindopril. In such experimental conditions there was no longer a difference in renal filtration between fed and fasted rats. These data indicate that 1) postprandial increase in glomerular filtration is to some extent related to the renin-angiotensin system activity; 2) short-term reduction of food intake reduces proteinuria even in senescent rats, although the feeding dependence of the glomerular filtration is blunted with age.
authors.affiliation: Département de Biologie, Centre d'Etudes Nucléaires de Saclay, Gif-sur-Yvette, France.
authors.forename: B
authors.initials: B
authors.lastname: Corman
authors.forename: S
authors.initials: S
authors.lastname: Chami-Khazraji
authors.forename: J
authors.initials: J
authors.lastname: Schaeverbeke
authors.forename: J B
authors.initials: JB
authors.lastname: Michel
mesh_terms: D000818:Animals; D001794:Blood Pressure; D004326:Drinking; D004435:Eating; D005215:Fasting; D005260:Female; D005919:Glomerular Filtration Rate; D007444:Inulin / Q000493:pharmacokinetics; D007668:Kidney / Q000254:growth & development*; D011507:Proteinuria; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D007444:Inulin