Inhibitory effect of a fullerene derivative, monomalonic acid C 60, on nitric oxide-dependent relaxation of aortic smooth muscle

Abstract

1. 1. Effects of a fullerene C 60 derivative, monomalonic acid C 60 (MMA C 60), on endothe-lium-containing or denuded aorta of rabbit, trachea and ileum of guinea pig, and stomach (fundus), vas deferens and uterus of rat were studied pharmacologically. 2. 2. MMA C 60 (10 −5 M) significantly reduced the maximum response of the relaxation induced by acetylcholine in endothelium-containing thoracic aorta of rabbit, and the acetylcholine-induced relaxation was recovered in the presence of superoxide dismutase (SOD, 250 units/ml). 3. 3. Nitric oxide-generating agent, S-nitroso- N-acetylpenicillamine, caused the relaxation of aorta without endothelium in a concentration-dependent manner, and the concentration-response curve was shifted to the right in the presence of MMA C 60. This inhibitory effect of the derivative was also masked in the, presence of superoxide dismutase (SOD). 4. 4. Sodium nitroprusside-induced relaxation was not affected by either MMA C 60 or SOD. In the other tissues, this C 60 derivative had no effect on the responses induced by any agonist. 5. 5. These observations indicate that MMA C 60 inhibits the endothelium-dependent relaxation induced by acetylcholine but does not affect the agonist-induced contractile response of smooth muscle.