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

Prostaglandins (PGs) such as PGE(2) and PGI(2) are vasodilators, and leukot rienes (LTs) such as LTB4 and LTC4 are vasoconstrictors. Our previous studi es have shown that salicylate ototoxicity is associated with decreased leve ls of PGs and increased levels of LTs. We hypothesized that vasodilating PG s increase cochlear blood flow and vasoconstricting LTs decrease cochlear b lood flow. PGE(2), Iloprost (a PGI(2) analog), LTB4, and LTC4 were applied to the round window membranes of chinchillas and cochlear blood flow was me asured with a laser Doppler flowmeter. PGE(2) increased cochlear blood flow , while LTC4 decreased cochlear blood flow. This findings show that vasodil ating PGs may have therapeutic implications fur sensorineural hearing loss and/or vertigo by increasing cochlear blood flow. Vasoconstricting LTs may cause hearing loss by decreasing cochlear blood flow.