Inflammatory reaction via arachidonic acid cascade after intravitreal injection of endothelin-1.

PURPOSE

To investigate the characteristics of anterior chamber inflammatory reaction induced by intravitreal injection of endothelin-1 (ET-1).

METHODS

The time course of changes in aqueous protein concentration (APC) after intravitreal injection of 10(-4), 10(-5), 10(-6) and 10(-7) M ET-1 into rabbit eyes was measured with a laser flare-cell meter. The influence of a topical diclofenac sodium (DFNa) pre- and post-treatment was assessed. Aqueous prostaglandin E2 and leukotriene B4 concentration was quantified using a radioimmunoassay technique.

RESULTS

Intravitreal injection of 10(-4) and 10(-5) M ET-1 significantly increased APC, while 10(-6) and 10(-7) M ET-1 did not induce anterior chamber inflammation. After 10(-5) M ET-1 injection, APC reached a maximum at 4 h post-treatment and returned to a normal level 48 h after injection. Eyes treated with 10(-4) M ET-1 displayed a bi-phasic time course, with peak values observed 4 to 8 h as well as 48 h after administration. Pre- and post-treatment with topical DFNa completely suppressed the APC increase in the 10(-5) M ET-1 preparation, and considerably inhibited it in the 10(-4) M ET-1 preparation. After ET-1 injection, aqueous prostaglandin E2 concentration increased significantly, followed by an increase in APC. There were no changes in leukotriene B4 concentration.

CONCLUSIONS

ET-1 induces anterior chamber inflammation via the cyclooxygenase pathway of the arachidonic acid cascade. The lipoxygenase pathway is not involved in this reaction.