Export of cyclic AMP by avian red cells and inhibition by prostaglandin A1

The mechanism by which PGA1 inhibits cAMP export by avian red cells was studied, to provide details on the molecular mechanism of a prostaglandin action and on the process of cAMP export itself. The interaction of PGA1 with pigeon red cells is a multi-step process of uptake, metabolism and secretion. [3H]PGA rapidly enters red cells and is promptly metabolized (V/sub max/ ≥ 1 nmol/min/107 cells) to a compound (5) that remains in the aqueous layer after ethyl acetate extraction. Chromatographic analyses, amino acid content and fast atom bombardment mass spectrometry reveal that the polar metabolite is conjugated with glutathione (PGA1-GSH) at C-11 via a thioether bond and is largely (80%) reduced to the C-9 hydroxyl derivative