Aminoxidase activity of ceruloplasmin was measured in the serum of 120
people (between 45 and 102 years of age) using the p-phenylenediamine
method. A negative linear age-correlation (-30% for the whole lifespa
n; P < 0.01) was established in this activity with increasing age, nev
ertheless the total copper content of blood did not change in the same
age-range as measured by an atomic absorption spectrophotometric meth
od. Increasing ionic strength, in vitro, caused an exponential decline
in blood ceruloplasmin aminoxidase activity of both middle aged and e
lderly subjects. The age-dependent decrease in ceruloplasmin activity
could have a negative effect on the antioxidant functions of blood, an
d finally on the aging process itself.