Determination of phosphodiesterase activity in rat mast cells using the fluorescent cAMP analogue anthraniloyl cAMP

Abstract Cyclic AMP and the isozyme families that control its concentration have an important role in rat mast cells. We have attempted to determine the total phosphodiesterase activity in rat mast cells by means of specific and non-specific inhibitors of phosphodiesterases. We used a fluorescent analogue of cAMP, 2′- O -anthraniloyl cAMP, the fluorescence intensity of which decreases when hydrolysed by phosphadiesterase (PDE), providing a measurement of total activity of PDE. The PDE inhibitors produced a decrease in the fluorescence fall. Therefore, we can establish that at least Type I, III, IV and probably Type V PDE are present in rat mast cells. We have also studied the effect of these PDE inhibitors on histamine release elicited by compound 48/80 and sodium fluoride. Chlorpromazine, a Type I PDE inhibitor, only slightly inhibits the fluoride-evoked response, while, on the other hand, milrinone, a Type III PDE inhibitor, does not modify the response to compound 48/80.