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Lege Artis Medicinae

JULY 14, 2007

[CONTROVERSIAL EFFECTS OF NITRIC OXIDE: INTEGRITY AND TOXICITY]

KISS Róbert Gábor, BÉRES Bernát János

[Nitric oxide is a key molecule of the human body. Since its discovery, a library of books and papers have been published on its physiological and pathophysiological role. It is involved in almost all pathological processes. In healthy individuals nitric oxide plays a crucial role in the vascular regulation by protecting against atherosclerosis, myocardial infarction and stroke. In the central nervous system, nitric oxide in its function as a neurotransmitter is responsible for synaptic plasticity, long-term potentiation, memory and a number of neuroendocrine control mechanisms. Furthermore, during inflammation and host defense, macrophages and neutrophils produce nitric oxide that has antibacterial, antiviral, and tumour cell killing activity. In pathologic conditions, however, nitric oxide reacts with superoxide anion to form peroxynitrite that damages the enzymes of the mitochondrial respiratory chain, superoxide-dismutase, reduced glutathion and activates or inactivates signalling molecules. During ischaemia- reperfusion, nitric oxide and peroxynitrite contribute to nitrative/nitrosative stress, DNAfragmentation and consequent polyADP-ribosepolymerase- 1 enzyme activation both in coronary thrombosis and ischaemic stroke.]