In these studies, we propose to use the skin as a relatively non-invasive model to examine cardiovascular and endothelial function in obese women with and without PCOS. Data have indicated an important role for testosterone in influencing the peripheral microcirculation. While testosterone can lead to vasodilation in the peripheral microcirculation in both men and in women without PCOS, testosterone appears to induce vasoconstriction in women with PCOS. The differential response between women with and without PCOS, and between men and women may be the result of differential ET-1 actions in the vessel, and regulated by the receptor subtype is involved in these actions.