Nitrates, Nitrites and the Cardiovascular System: The first reports of dilating the coronary arteries by pharmacologic doses of inorganic nitrites were published almost 100 years ago (37). Recent studies have found a vasodilatory effect of much lower levels of circulating nitrites (38-41). Organic nitrites, derived from plants, are much more potent than inorganic nitrites. The preferential conversion of nitrites to NO under conditions of hypoxia may well have important clinical applications in the care of patients with myocardial ischemia (39, 40, 42). Multiple studies have demonstrated that increased consumption of fruits and vegetables provides a cardio-protective effect (43-46). It has also been shown that inorganic sodium nitrate, administered in the quantities corresponding to the amount present in a serving of nitrate-rich vegetables, reduced diastolic blood pressure by 4 mm Hg in one study (47) and had a comparable effect on systolic pressure in a later study with a larger number of participants (48). In a model of high blood pressure and renal disease induced by chronic blockage of NOS, nitrite supplementation ameliorated the blood pressure and a low dose of oral nitrites protected against kidney injury (49). Administration of nitrates, either inorganic or through natural sources, has been shown to have demonstrable therapeutic effects in multiple organ systems in many different species, including humans. These include improved cardiovascular parameters in mouse and rat models of cardiac ischemia (50-52), decreased ulcer formation and improved mucus secretion in the stomach in a rat model of gastric ulcers (53, 54), decreased platelet aggregation, decreased blood pressure, improved endothelial function, decreased oxygen consumption with moderate or maximal exercise, and improved work efficiency in human studies (55-62). Administration of inorganic nitrites has been found to have a similarly wideranging list of benefits in rodent, canine and human studies (29,36,38, 49, 63-75). In studies involving mouse models of sepsis, or disseminated bacterial infection, causing dangerously low blood pressure or septic shock, administration of nitrites improved survival and reduced mitochondrial damage, tissue damage from infarction, hypothermia and oxidative stress (75). Because nitric oxide is a gas, it is possible to administer it through inhalation, and this approach has been used to treat babies with high blood pressure in the pulmonary circulation (76). In animal studies, inhaled nitrites have improved hypertension in the pulmonary circulation as well (42). Transplantation studies: COMING SOON!!
Posted on: Tue, 24 Sep 2013 03:47:52 +0000
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