Age-related changes in the antioxidative potential of cerebral microvessels.

To determine if aging in rats is associated with increased susceptibility of cerebral microvessels to oxidative damage microvessels from the cerebrum of 4-, 12-, 18- and 26-month-old male Fischer 344 rats were studied. The malondialdehyde (MDA) (micrograms/mg protein) content of cerebral microvessels from 12-month-old rats (0.032 +/- 0.002) was significantly higher than that in 4-month-old rats (0.020 +/- 0.015) P < 0.01. The difference between 26-month-old (0.025 +/- 0.002) and 4-month-old rats did not reach statistical significance. The antioxidative potential was measured in the presence of a peroxy radical generator 2,2'-azobis(2-amidionopropane)hydrochloride (AAPH) with monitoring of the fluorescence of phycoerythrin at 37 degrees C. The free radical quenching activity of cerebral microvessels expressed as % inhibition of phycoerythrin oxidation by AAPH was significantly reduced in 12-month-old (33.6 +/- 4.6%) and 18-month-old rats (26.9 +/- 1.4%) compared with 4-month-old rats (54.3 +/- 4.9%) (P < 0.01). The 26-month-old rats (46.4 +/- 4.6%) were not significantly different from 4-month-old rats. It is concluded that aging is associated with increased lipid peroxidation byproducts in cerebral microvessels along with a transient decrease in their antioxidative capacity.