Effect of age on the activity of ceruloplasmin of human blood.

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 lifespan; P < 0.01) was established in this activity with increasing age, nevertheless the total copper content of blood did not change in the same age-range as measured by an atomic absorption spectrophotometric method. Increasing ionic strength, in vitro, caused an exponential decline in blood ceruloplasmin aminoxidase activity of both middle aged and elderly subjects. The age-dependent decrease in ceruloplasmin activity could have a negative effect on the antioxidant functions of blood, and finally on the aging process itself.