HYPOXIC AND HYPEROXIC EFFECT ON BLOOD PHOSPHODIESTERASE ACTIVITY IN YOUNG AND OLD RATS

In the present work we describe phosphodiesterase (PDEs) activity in t he blood of young and old rats kept under hypoxic or hyperoxic normoba ric conditions in order to correlate the age-change response with PDE levels and oxygen supply. PDE is important in the process of energy su pply and as a modulator and mediator of several cellular functions. Th ree 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 compo sed of young rats (2 months of age) and old rats (25 months of age). A fter the exposure the rats were anaesthetized and blood samples were c ollected using an intracardiac catheter. The results show: a) in the c ontrol group, no significant difference between the PDE activities of old and young rats; b) a significant increase in PDE occurred after hy poxic and hyperoxic treatment in both young and aged rats; c) the incr ease 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. T he 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 expr ession occurring in the blood as a consequence of hypoxic or hyperoxic treatment is probably a necessary protective response for the body ag ainst alteration from oxidative metabolism and to maintain the body in homeostatic ranges for energy requirements. (C) 1998 Elsevier Science Inc.