Takaharu Ishibashi, Junko Yoshida and Matomo Nishio
Department of Pharmacology, Kanazawa Medical University, Uchinada, Ishikawa
920 - 0293, Japan
Abstract: Diverse attention should be paid to evaluating NOx
(NO2- and NO3-) in plasma as
an index of endothelial nitric oxide (NO) formation in vivo. Nitric oxide,
which subsequently appears as NOx, originates from different types of NO
synthase and from nonenzymatic reactions. NOx also comes from exogenous
sources such as food and gastrointestinal microorganisms. The fate of the
NO incorporated into activation of guanylate cyclase, formation of nitrosyl
hemoglobin (or nitrosohemoglobin), nitrosothiols, peroxynitrite and its
derivatives and other possible compounds is not clear at present. However,
some of these compounds would produce NOx as by-products or as final products
through metabolism. Therefore, plasma NOx contains information about these
pathways, although how extensively these factors contribute to plasma NOx
has not been quantitatively defined. A theoretical simulation of NOx in
the systemic circulation indicates that only small changes are expected
by inhibition or stimulation of endothelial NO production. Measuring NOx
production during coronary circulation has the advantage that some degree
of NOx accumulation is expected from intact endothelial cells because an
excretion system is absent in the heart.
Keywords: Cardiovascular system, Blood, Nitric oxide (NO), Nitrite (NO2-),
Nitrate (NO3-)