Effect of hexasulfobutylated C(60) on the isolated aortic ring of guinea pig.

The effects of hexasulfobutylated C(60) (FC(4)S) and monomalonic acid C(60) (MMA C(60)), the fullerene C(60) derivatives, on isolated endothelium-containing or endothelium-denuded aorta of guinea pig were studied pharmacologically in vitro. In the endothelium-containing preparation of the aortic rings, phenylephrine (PHE) elicited contracture and acetylcholine (ACh) elicited a relaxing effect on the PHE-precontracted preparation. In the PHE-precontracted preparation, MMA C(60) (10 micromol/l) did not elicit a relaxing effect on the PHE-precontracted preparation. However, MMA C(60) (10 micromol/l) significantly reduced the maximum response of the relaxation elicited by ACh. FC(4)S itself significantly relaxed the PHE-precontracted aortic rings. ACh-induced relaxation in PHE-precontracted endothelium-containing strips of the aortic rings was significantly potentiated if pretreated with FC(4)S (10 micromol/l). In the denuded aortic rings, FC(4)S did not elicit the relaxing effect in the PHE-precontracted preparation. The relaxing effect of FC(4)S on the PHE-precontracted preparation was not altered when superoxide dismutase (250 units/ml) was pretreated. However, the relaxing effect was reduced when N(G)-nitro-L-arginine methyl ester (L-NAME, 1 mmol/l) or methylene blue (1 micromol/l) was pretreated. These results demonstrated that the vasorelaxation effect of FC(4)S on the PHE-precontracted aortic ring is partly dependent on the release of nitric oxide (NO) or an NO-derived substance from the vascular endothelium.