In vivo studies have also assessed forearm blood flow after brachial artery infusion in response to NG-monomethyl-l-arginine (L-NMMA, which binds and competitively inhibits eNOS), methacholine chloride (MCh, a muscarinic acetylcholine receptor agonist that activates eNOS in ECs) and sodium nitroprusside (a NO donor that bypasses eNOS and was used to define endothelium-independent NO-mediated vasodilation) in well-controlled versus poorly controlled T1DM patients in which cholesterol and insulin levels were matched [105]. The gene discussed is NOS3; the disease is type 1 diabetes mellitus.