Leucotrienes, SRS-A and the vascular manifestations of PCA.

In order to study possible mediators of the vascular manifestations of passive cutaneous anaphylaxis (PCA), several arachidonic acid metabolites were injected into guinea-pig skin. SRS-A, LTB4, LTC and LTD increased vascular permeability, responses to LTs being enhanced by PGE2. Mepyramine inhibited responses to histamine, but not those to SRS-A and LTs; the latter were inhibited by the SRS-A antagonist FPL-55712. Both mepyramine and FPL-55712 exert limited inhibitory effects on vascular permeability during PCA. Leukotrienes may contribute towards vascular permeability during PCA.