# Quercetin Dilates Retinal Arterioles via Nitric Oxide-Dependent Mechanisms in Rats

## TL;DR

Quercetin, a plant compound, dilates retinal blood vessels in rats through nitric oxide, without affecting heart rate or blood pressure.

## Contribution

This study demonstrates quercetin's retinal vasodilation via nitric oxide in rats, suggesting its potential for ocular disease prevention.

## Key findings

- Quercetin induces retinal arteriolar dilation in a dose-dependent manner.
- The effect is suppressed by an NO synthase inhibitor, indicating nitric oxide dependence.
- Quercetin does not alter systemic blood pressure or heart rate.

## Abstract

The purpose of this study was to investigate whether quercetin, a flavonoid abundantly found in onion leaves and other plant foods, induces the dilation of retinal blood vessels in rats. The time-course changes in retinal arteriolar diameter were measured using a retinal circulation evaluation system based on a high-resolution digital fundus camera developed in our laboratory. The intravenous administration of quercetin (10–100 µg/kg/min) increased the retinal arteriolar diameter in a dose-dependent manner. This vasodilatory effect of quercetin was almost completely suppressed through an intravitreal pretreatment with Nω-nitro-l-arginine methyl ester (l-NAME), a nitric oxide (NO) synthase inhibitor. In contrast, the systemic intravenous infusion of quercetin did not cause significant changes in the systemic blood pressure and heart rate. These results suggest that NO production plays an important role in the quercetin-induced dilation of retinal arterioles. Quercetin, which is abundantly present in several plant foods and possesses antioxidant properties, may be a useful agent for the prevention of various ocular diseases associated with visual impairment caused by reduced retinal blood flow.