Leukotriene antagonists attenuate late phase nitric oxide production during the hypersensitivity response in the conjunctiva.

OBJECTIVE

To investigate the role of cysteinyl leukotrienic (cysLT) antagonists on conjunctival nitric oxide (NO) release in experimental allergic conjunctivitis.

METHODS

Zafirlukast, disodium cromoglycate or levocabastine were instilled into the C48/80-challenged eyes of male Wistar rats. The conjunctival histamine content and nitrite levels in the lavage fluid were quantified 45 min and 6 h post-challenge, respectively. Instillation of phosphate buffer saline reflected control treatment. Statistical analyses were performed by ANOVA.

RESULTS

Topical challenge with C48/80 significantly altered the histamine and nitrite levels to 44.6 +/- 2.8% and 233 +/- 19% of the control (P < 0.01), respectively. Instillation of zafirlukast, disodium cromoglycate or levocabastine reversed the effect of C48/80 on nitrite release, its levels being 150 +/- 27%, 54 +/- 14% and 121 +/- 20% of the control (P > 0.05), respectively. Zafirlukast had no effect on the histamine content.

CONCLUSIONS

By inhibiting the late-phase NO component of the conjunctival hypersensitivity response, cysLT antagonists might contribute to the management of ocular inflammatory responses.