SLOW REACTING SUBSTANCE (SRS) FROM IONOPHORE A23187-STIMULATED PERITONEAL MAST-CELLS OF THE NORMAL RAT .2. EVIDENCE FOR A PRECURSOR ROLE OF ARACHIDONIC-ACID AND FURTHER PURIFICATION

Abstract

The generation of SRS from ionophore A23187-stimulated rat peritoneal mast cells was enhanced by arachidonic acid (AA). This SRS generation was inhibited by 5,8,11,14-eicosatetraynoic acid (ETYA), an acetylenic analogue of AA and an inhibitor of both fatty acid cyclooxygenase and lipoxygenase. Indomethacin, a fatty acid cyclooxygenase inhibitor, had an enhancing effect upon SRS generation. SRS generation possibly occurred through an ETYA sensitive step, perhaps a lipoxygenase. Radiolabel from [14C]-AA was incorporated into SRS with comigration of radioactivity and bioreactivity in silicic acid and TLC. Upon silicic acid chromatography, the active principle was eluted in the methanol fraction. Two-dimensional TLC revealed chromatographic separation from other known spasmogenic substances and phospholipids. Mast cell SRS displayed physiochemical properties similar to rat basophilic leukemia cell SRS, i.e., that mast cell SRS generation was enhanced by AA inhibited by ETYA but not by indomethacin, incorporation of [14C]-AA into the active principle and similar behavior during purification in silicic acid and TLC. [The notion that SRS is a chemical mediator elaborated from cells involved in the allergic response was discussed.].