Abstract: In this study we assessed the vasodilatory effects of nitropirin, a new nitroderivative of aspirin, in vitro. Nitropirin contains a nitric oxide (NO) moiety, which is considered to act both by inhibiting cycloxygenase and by releasing NO in tissues. Nitropirin could relax both the endothelium-intact and endothelium-denuded rabbit aorta rings in a concentration-dependent manner. The values of EC50 were 7.26×10^-6 mol·L^-1 on the endothelium- intact aorta rings and 1.25×10^-5 mol·L^-1 on the endothelium-denuded aorta rings, which were considered insignificant compared with those of nitroglycerin (4.69×10^-6 mol·L^-1 and 5.3×10^-6 mol·L^-1 respectively, P>0.05). Aspirin showed no significant relaxant activity on aorta strips in a wide rang. from 1×10^-8 mol·L^-1 to 1×10^-4 mol·L^-1. The results demonstrate that nitropirin has endothclium-independent relaxant activity on the arteries. The mechanism of this property may be related to the ability of providing NO in target tissues.

Key words: 3-Nitrooxypropy1-2-acetyloxy benzoate, 3-Nitrooxypropy1-2-acetyloxy benzoate, Nonsteroidal anti-inflammatory drugs, Nonsteroidal anti-inflammatory drugs, Nitric oxide, Nitric oxide, Vasorelaxation, Vasorelaxation, Aorta rings, Aorta rings, Rabbit, Rabbit