Chronic L-arginine Prevents Cholesterol-attenuation of Vasodilation to Acetylcholine and Serotonin

Acute administration of the amino acid L-arginine has been shown to reverse cholesterol attenuated endothelium-dependent vasodilation. A role for chronic L-arginine as a protectant against cholesterol-induced endothelial dysfunction was studied in the rat cremaster muscle microcirculation. Pellets containing L-arginine (200 mg, 3 week release) and corresponding placebo were implanted subcutaneously in male Sprague-Dawley rats. The rats were then fed either a normal chow diet or chow diet supplemented with 1% cholesterol and 0.5% cholic acid for 3 weeks prior to in vivo experimentation. In vivo television microscopy was used to quantitate microvascular diameter changes. The third order dilator response to both acetylcholine and serotonin was significantly greater in the L-arginine treated group fed the high cholesterol diet compared to the placebo treated group on the same diet. There was no difference in dilator response between the L-arginine treated cholesterol rats and either L-arginine or placebo trea...