title: Renal function and functional reserve in healthy elderly individuals.
abstract: BACKGROUND
  Aging is characterized by a decline in renal function and by a susceptibility to renal diseases. However it is not clear whether the observed changes are solely hemodynamic, structural or both. We evaluated renal function, functional reserve (RFR) and morphology in healthy elderly individuals.
  
  
  METHODS
  Healthy participants (n=19) were divided into young (n=6, age range 25-37 years), middle-aged (n=6, 44-74 years) and elderly (n=7, 81-96 years). Nitric oxide (NO), plasma renin activity (PRA) and aldosterone, renal plasma flow (RPF) by p-aminohippurate clearance (CPAH) and glomerular filtration rate (GFR) by inulin clearance (CIN) were determined before and during maximal vasodilating stimuli, induced with the infusion of dopamine and amino acids. Glomerular sclerosis, lumen area and wall thickness of afferent arterioles were determined by kidney biopsy from 36 healthy kidney donors and from 6 nephrectomies for renal carcinoma.
  
  
  RESULTS
  GFR and RPF were slightly reduced in elderly individuals whereas filtration fraction (FF) was increased. GFR and RPF did not increase in the elderly after maximal vasodilating stimuli as in young and middle-aged subjects suggesting a reduction of RFR. NO, increased at baseline, did not increase further after vasodilating stimuli; while on the contrary, PRA, similar in the 3 groups at baseline, was not reduced by vasodilating stimuli in the elderly. Sclerotic glomeruli but not glomerular volume were significantly increased by aging. Afferent arteriole lumens were reduced by aging whereas wall thickness was unchanged.
  
  
  CONCLUSIONS
  Renal function is preserved with aging in healthy subjects at the expense of a complete reduction of RFR. RFR may be wasted to compensate for the increased number of sclerotic glomeruli. Vascular changes, suggested by reduced arteriolar lumen, may be so advanced that even in the presence of high levels of vasodilatory molecules, kidneys are not responsive anymore to maximal vasoactive stimuli.
authors.affiliation: Unit of Nephrology, Dialysis and Transplantation, IRCCS Policlinico San Matteo, University of Pavia, Pavia - Italy. espositociro56@hotmail.com
authors.forename: Ciro
authors.initials: C
authors.lastname: Esposito
authors.forename: AnnaRita
authors.initials: A
authors.lastname: Plati
authors.forename: Tiziana
authors.initials: T
authors.lastname: Mazzullo
authors.forename: Gianluca
authors.initials: G
authors.lastname: Fasoli
authors.forename: Andreana
authors.initials: A
authors.lastname: De Mauri
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Grosjean
authors.forename: Filippo
authors.initials: F
authors.lastname: Mangione
authors.forename: Francesca
authors.initials: F
authors.lastname: Castoldi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Serpieri
authors.forename: Flavia
authors.initials: F
authors.lastname: Cornacchia
authors.forename: Antonio
authors.initials: A
authors.lastname: Dal Canton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism / Q000473:pathology; D000450:Aldosterone / Q000097:blood; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D007677:Kidney Function Tests; D007678:Kidney Glomerulus / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood; D012016:Reference Values; D012079:Renal Circulation / Q000187:drug effects; D012083:Renin / Q000097:blood; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D009569:Nitric Oxide; D000450:Aldosterone; D012083:Renin