Hyperthyroidism enhances endothelium-dependent relaxation in the rat renal artery

These data indicate that short-term treatment with T3 increases endothelium-dependent relaxation, most probably by increasing vascular cyclic AMP content. Following treatment with T3 for 8 weeks, expression of the endothelial NO synthase was enhanced. During this phase, NO appears to be the predominant endothelium-derived vasodilator.