[The correlative study on nitric oxide and cotinine nicotine metabolite in smokers' urine]

In order to observe the changes of nitric oxide (NO) affected by smoking and their relationship in vivo.

60 male nonsmoker as the control group, 192 male smoked as the study group which was divided into 4 subgroups (1-10, 11-20, 21-30 and > 30) according to the number of cigarettes smoked per day. The metabolite of nicotine-cotinine in urine was assayed by means of barbituric acid. Cotinine was used as an objective indicator to reflect the smoking quantity. The urinary NO (NO2.-) was determined with colorimetric estimation.

The urinary cotinine level in the 4 subgroups were 6.6 +/- 1.6, 25.1 +/- 6.2, 37.8 +/- 8.5, 53.6 +/- 8.3 (mumol/L) respectively. The urinary NO of nonsmokers were 4.43 +/- 0.97 (mumol/L), in the 4 subgroups it was 3.04 +/- 0.07, 2.75 +/- 0.05, 2.18 +/- 0.01, 1.60 +/- 0.01 (mumol/L) respectively. The results of statistical analysis between the 4 subgroups were t = 4.2894, P < 0.01; t = 2.7446, P < 0.01; t = 2.7667, P < 0.01 accordingly. As compared between the 4 subgroups of smokers and the nonsmokers, the statistical results were t = 2.7118, P < 0.01; t = 3.1826, P < 0.01; t = 3.2100, P < 0.01; t = 4.6600, P < 0.01; respectively. The statistical differences between the 4 subgroups were t = 2.9286, P < 0.01; t = 3.0357, P < 0.01; t = 3.8181, P < 0.01; t = 2.2160, P < 0.05 respectively. There was a good positive correlation between the number of cigarette smoked and urinary cotinine content (r = 0.8626, P < 0.01), also a significant negative correlation between it and urinary NO level (r = -0.6596, P < 0.05). A negative correlation could be observed between urinary cotinine and NO (r = -0.6026, P < 0.05).

With the increase of quantity and duration of smoking, the NO content in vivo will decrease, suggested that the vascular endothelial cells could be damaged severely.