SLOW REACTING SUBSTANCE (SRS) FROM IONOPHORE A23187-STIMULATED PERITONEAL MAST-CELLS OF THE NORMAL RAT .1. CONDITIONS OF GENERATION AND INITIAL CHARACTERIZATION

Abstract

When rat peritoneal mast cells were exposed to the ionophore A23187, a principle was released that possessed the biologic properties of SRS from various sources. The response was dose, time and temperature dependent with no activity demonstrated in unstimulated cells. Supporting evidence that the mast cell product was similar or identical to SRS obtained from other sources included: appropriate differential bioassay profile, resistance to lipolysis and proteolysis, acid lability and base stability, inactivation by limpet arylsulfatase and inhibition by low concentrations [7-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-2-hydroxy-propoxy]-4-oxo-8-propyl-4H-1-benzopyran-2-carboxylic acid monosodium salt] FPL 55712. The isolated rat peritoneal mast cell contains the biosynthetic capacity to produce a bioreactive substance with the properties of SRS. Because SRS immunologically released from a variety of tissues, it has been thought to be derived from mast cells and to be an important mediator of acute hypersensitivity states including bronchial asthma.