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Takayuki Tokimoto, Kozo Shinagawa
Nitric Oxide Generation in Aqueous Solutions of Cigarette Smoke and Approaches to Its Origin
By using the ESR spin trapping technique with the NmethylDglucamine dithiocarbamate (MGD)2-Fe(II) complex, the generation of nitric oxide (NO), a gaseous free radical, was observed in NO spin trapping solution bubbled with the filtered mainstream of cigarette smoke. The ESR signal with a threeline spectrum characteristic of an NO radical, which was not observed immediately after bubbling of smoke, started rapidly increasing with time up to around 25 min after the last addition of ferrous ions Fe(II), and then slowly approached a peak value dependent on the burned cigarette mass and on the smoking speed. The production of NO was, however, much affected by air oxidation and enhanced by the addition of ascorbic acid. A certain concentration of sodium nitrite (NaNO2) solution, in which nitrite NO2 is assumed as the main origin of the NO, mimicked closely the time course of NO generation resulting from the smoke of one cigarette. The cigarette smoke that was passed through alkaline pyrogallol solution as a deoxidizer; however, it exhibited an unchanged intensity of NO signal throughout the measurement. These results strongly suggest that NO would be gradually reproduced from NO2 in the reductive aqueous solution containing excess Fe(II) through NO2, which is initially formed and is concomitantly oxidized from NO in cigarette smoke.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 382, 11/2001
Pages: 1613 - 1619