Hypoxic and hyperoxic effect on blood phosphodiesterase activity in young and old rats

In the present work we describe phosphodiesterase (PDEs) activity in the blood of young and old rats kept under hypoxic or hyperoxic normobaric conditions in order to correlate the age-change response with PDE levels and oxygen supply. PDE is important in the process of energy supply and as a modulator and mediator of several cellular functions. Three groups of Wistar rats were kept in room air, 10–12 % oxygen for 12 days and 98–100% oxygen for 60 hrs respectively. Each group was composed of young rats (2 months of age) and old rats (25 months of age). After the exposure the rats were anaesthetized and blood samples were collected using an intracardiac catheter. The results show: a) in the control group, no significant difference between the PDE activities of old and young rats; b) a significant increase in PDE occurred after hypoxic and hyperoxic treatment in both young and aged rats; c) the increase in PDE activity was more evident in the young rather than the old rats; and d) the aged rats are less responsive to oxygen variation. The results demonstrate that young and aged rats respond to variations in the oxygen supply. Hypoxia and hyperoxia show different age-related intensity level response. We conclude that the alteration in PDE expression occurring in the blood as a consequence of hypoxic or hyperoxic treatment is probably a necessary protective response for the body against alteration from oxidative metabolism and to maintain the body in homeostatic ranges for energy requirements.