Increased cyclic AMP-phosphodiesterase activity during inflammation and its inhibition by anti-inflammatory drugs

Cyclic AMP-phosphodiesterase (cAMP-PDE) activity was determined in edematous and granulomatous tissues in carrageenin hind paw edema and cotton pellet granuloma of rats. In the time course study, maximum cAMP-PDE activity was observed in edematous tissue at 3-6 h after carrageenin injection and in granulomatous tissue from the 7th day onwards after cotton pellet implantation. Pretreatment with anti-inflammatory drugs inhibited significantly the increase in cAMP-PDE activity in edematous and granulomatous tissues. It was also observed that the increase in cAMP-PDE activity in edematous tissue paralleled the increase in migrated cells (leukocytes). Therefore, it is possible that the inhibition of cAMP-PDE activity by anti-inflammatory drugs may be the result of inhibition of cellular infiltration into the inflammatory site. It is suggested that phosphodiesterase may be an additional biochemical parameter for assessing cellular events of inflammation and consequently useful for the evaluation of anti-inflammatory drugs.