Effects of leukotrienes and prostaglandins on cochlear blood flow in the chinchilla

Prostaglandins (PGs) such as PGE₂ and PGI₂ are vasodilators, and leukotrienes (LTs) such as LTB₄ and LTC₄ are vasoconstrictors. Our previous studies have shown that salicylate ototoxicity is associated with decreased levels of PGs and increased levels of LTs. We hypothesized that vasodilating PGs increase cochlear blood flow and vasoconstricting LTs decrease cochlear blood flow. PGE₂, Iloprost (a PGI₂ analog), LTB₄, and LTC₄ were applied to the round window membranes of chinchillas and cochlear blood flow was measured with a laser Doppler flowmeter. PGE₂ increased cochlear blood flow, while LTC₄ decreased cochlear blood flow. This findings show that vasodilating PGs may have therapeutic implications for sensorineural hearing loss and/or vertigo by increasing cochlear blood flow. Vasoconstricting LTs may cause hearing loss by decreasing cochlear blood flow.