Jf. Reckelhoff et al., CHANGES IN NITRIC-OXIDE PRECURSOR, L-ARGININE, AND METABOLITES, NITRATE AND NITRITE, WITH AGING, Life sciences, 55(24), 1994, pp. 1895-1902
Citations number
26
Categorie Soggetti
Biology,"Medicine, Research & Experimental","Pharmacology & Pharmacy
The present study was performed to test the hypothesis that excretion
of nitric oxide metabolites, nitrate and nitrite, are decreased with p
rogressive aging in rats and that a decrease in nitric oxide precursor
, L-arginine, also decreases with aging. Urinary nitrate/nitrite excre
tory rates and serum L-arginine levels were measured in male Sprague D
awley rats, ranging in ages from 3 to 25 months. Proteinuria increased
dramatically with aging. Conversely, urinary nitrate/nitrite excretio
n decreased by 50% and 80% in rats, aged 12 months and 17 months, resp
ectively. There was no further decrease in urinary nitrate/nitrite exc
retion in very old rats, aged 23-24 months. Glomerular filtration rate
(GFR) was also measured in some of the rats, aged 3-5 mos and 17 mos.
GFR was not different between old and young rats, suggesting that a d
ecrease in GFR could not account for the decrease in urinary nitrate/n
itrite excretion in the old rats. However, serum L-arginine levels wer
e decreased with aging, by 30% and 50% in rats, aged 13-15 months and
24-25 months, respectively, when compared with young rats. These data
confirm our hypothesis and suggest that nitric oxide (NO) production m
ay decrease with aging and that one mechanism by which nitric oxide pr
oduction could be decreased with age is a lack of the endogenous subst
rate, L-arginine. Because NO has been implicated to be involved in man
y physiological processes, age-related decreases in NO production coul
d have far-reaching adverse effects in the aging individual.