AGE-RELATED-CHANGES IN THE ANTIOXIDATIVE POTENTIAL OF CEREBRAL MICROVESSELS

To determine if aging in rats is associated with increased susceptibil ity 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) (mu g/mg protein) content of cerebr al microvessels from 12-month-old rats (0.032 +/- 0.002) was significa ntly 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 potenti al was measured in the presence of a peroxy radical generator 2,2'-azo bis(2-amidionopropane)hydrochloride (AAPH) with monitoring of the fluo rescence of phycoerythrin at 37 degrees C. The free radical quenching activity of cerebral microvessels expressed as % inhibition of phycoer ythrin 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-mon th-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 b yproducts in cerebral microvessels along with a transient decrease in their antioxidative capacity.