NOS3 and endothelial dysfunction: Finally, and importantly, L‐NMMA was inversely and the L‐arginine/L‐NMMA ratio positively correlated with brachial artery FMD, suggesting that a relative L‐arginine deficiency related to elevated levels of the eNOS inhibitor L‐NMMA, may be a contributing factor to the endothelial dysfunction in postmenopausal women.