Dietary treatment of atherosclerosis abolishes hyperresponsiveness of retinal blood vessels to serotonin in monkeys.

BACKGROUND AND PURPOSE: Atherosclerosis alters vascular responses of the eye to serotonin. Augmented vasoconstrictor responses in the retina to serotonin are associated with functional impairment and may contribute to amaurosis fugax. The goal of this study was to test the hypothesis that dietary treatment of atherosclerosis restores vascular responses of the eye toward normal. METHODS: We measured blood flow to the retina using microspheres in six normal monkeys, five atherosclerotic monkeys, and five atherosclerotic monkeys that were fed a normal (regression) diet for 18 months. RESULTS: Infusion of 8 and 40 micrograms.min-1.kg-1 serotonin into the left atrium had little effect on blood flow to the retina in normal monkeys. In contrast, the high dose of serotonin reduced blood flow to the retina by a mean +/- SEM of 81 +/- 9% (p less than 0.05) in atherosclerotic monkeys. In monkeys that were fed the regression diet, serotonin had no effect on blood flow to the retina. CONCLUSIONS: Regression of atherosclerosis abolishes augmented responses of the retinal circulation to serotonin.