Leukotrienes and sensory innervation in blood-aqueous barrier disruption in the dog

The effect of a specific 5-lipoxygenase inhibitor, PF5901 (5% in corn oil), on disruption of the blood-aqueous barrier (BAB) in the dog was investigated using a unilateral mild paracentesis model. BAB breakdown was quantitated using anterior chamber fluorophotometry. Fluorescence in the eyes of the PF5901 group was not statistically significantly different (P greater than 0.05) from that in the vehicle group. A tendency towards greater fluorescein concentrations was noted in the PF5901 treated eyes. It was concluded that leukotrienes are not important mediators of BAB disruption in this model and that leukotriene inhibitors may actually exacerbate disruption due to shunting of arachidonate metabolism towards the cyclooxygenase and/or epoxygenase pathways. In a second experiment, the effects of proparacaine and flurbiprofen were evaluated on blood-aqueous barrier disruption and pupil size following a more severe paracentesis. Flurbiprofen dampened both barrier disruption and the miotic response but proparacaine suppressed neither reaction, suggesting that, in the dog, prostaglandins are more important mediators of the ocular irritative response than are sensory neuropeptides.