NO is synthesized from L-arginine by NO synthase (NOS) and it is an anti-thrombotic product of the endothelial cells. NO has been shown not only to mediate vasodilation but also to inhibit platelet aggregation and adhesion (12), prevent monocyte adherence to the endothelium (12), and prolong bleeding time (13). It has also been found to be responsible for reducing plasma fibrinogen levels (14) and to reduce platelet activation (15). Reduced NO bioavailability leads to impaired vasodilation, to abnormalities in the above functions and, as a consequence, enhances thrombotic events in humans (16).
Impairment of NO-mediated vasodilation has been shown in both type 1 and type 2 diabetes (17,18) and it may contribute to the accelerated development of macrovascular disease in diabetes. Recent studies using an inducible NO synthase (iNOS)-deficient mice shows that there is decreased response to acetylcholine in wild-type diabetic animals when compared to nondiabetic animals. No difference in response was, however, observed in the diabetic iNOS-deficient mice thus giving the first direct evidence that impairment of endothelium-dependent relaxation during diabetes is dependent on iNOS expression (19). Oxidized lipoproteins, which are present in increased levels in diabetes, may be behind the reduced NO activity in diabetes, as shown by several studies (20-22). Interestingly, NO may also influence lipoprotein oxidation. If cells are stimulated to express active NOS, their oxidative capability is lost (23). On the other hand, if conditions in the vessel wall favor the release of superoxide, NO can be converted to peroxynitrate, which is a powerful oxidant (24). Recently antioxidant status, lipid peroxidation and NO end-products were measured in a group of Asian-Indian patients with type 2 diabetes with and without nephropathy (25). This study confirmed that oxidative stress is increased and antioxidant defenses are compromised in patients with type 2 diabetes, and that these derangements are more severe in patients with nephropathy. Other possible factors behind reduced NO activity in diabetes include abnormalities in insulin and in the kal-likrein/kinin pathway.
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All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.