Release of slow reacting substance from rabbit ocular tissues

Investigations were carried out to determine whether any slow reacting substance (SRS) is released from the ocular tissues. The SRS activity was bioassayed using the guinea pig ileum in the presence of mepyramine and atropine. An SRS-specific antagonist, FPL55712, was also used to confirm SRS-induced ileum contraction. Incubation of the ocular tissue fragments of the rabbit with a Ca-ionophore A23187 resulted in a marked release of the SRS in the potency order of the choroid, ciliary body, conjunctiva and iris. The rabbit was sensitized with bovine serum albumin and complete Freund's adjuvant. Experimental uveitis was induced by injection of antigen into the vitreous body the sensitized rabbits. The SRS could not be detected in the aqueous humor 10-24 hours after the antigen injection but it was released markedly into the vitreous. The SRS from the vitreous humor of the rabbits with experimental uveitis was purified by high performance liquid chromatography, and leukotriene C4 and leukotriene D4 were identified. It was suggested that release of the SRS from the ocular tissues plays a role in allergic and nonallergic uveitis.