Assay of prostacyclin synthesis in intact aorta by aqueous sampling

Conversion of 1-¹⁴C-arachidonic acid (AA) to 6-keto-PGF_1α, the stable metabolite of prostacyclin (PGI₂) was assayed kinetically by employing an aqueous sampling technique. In this way, one can arrive at a kinetic view of PGI₂ synthesis from AA in intact tissue. The assay appears to be particularly suitable to tissues such as the aorta where PGI₂ constitutes the major metabolite of AA. The assay avoids the need for organic solvent extraction and relies on the essential absence of tissue binding of 6-keto-PGF_1α. The disappearance of AA can also be followed in this system but quantitation is complicated by avid tissue binding of the fatty acid. The assay, as described should be applicable to other vascular tissues and should greatly simplify kinetic analyses of prostacyclin synthesis.