Pilot Study Of The Effect Of Endogenous Sulfur Dioxide On Isolated Aortic Rings Of Rats

Sulfur dioxide(SO₂), as a major air polluter, has been paid more and more attention to its toxic effects. For about a decade, our lab has been engage in the research of toxicology effects of SO₂, and we found that SO₂ is a system toxin. We also found that inhalation SO₂ or celiac injection SO₂ derivatives on rat lead to lower significantly blood pressure. In our recently research, dual-directional regulation effects of SO₂ derivatives on isolated aortic rings of rats were discovered.In this research, the effects of endogenous SO₂ and its derivatives on the isolated aortic rings of rats were investiged.1. The distribution and toxicological effect of SO₂ in different organs of mouse after it is inhaledThe Kunming mice were exposed to SO₂ at different doses. Then the concentrations of sulfite in livers, kidneys, spleens and testis were determined by high performance liquid chromatography(HPLC) with fluorescence detection(FD). The results showed that: (1) Compared with control groups, sulfite concentration in all organs tested form mice in SO₂-exposed groups was significantly increased in a dose-dependent manner. (2) The levels of sulfite in spleens and testis were higher than in livers and kidneys from mice exposed to SO₂. In conclusion, SO₂ may transform into sulfite after it is inhaled and distributed into liver and other organs such as kidney, spleen and testis. Support the viewpoint that SO₂ is a systemic toxicant.2. The effects of endogenous sulfur dioxide and its metabolites on isolated thoracic aorta rings of rats The effects of noradrenaline(NE),acetylcholine(Ach) and sodium nitroprusside(SNP) on thoracic aorta rings of rats were observed using the ring tensions recording method. Levels of SO/SO₂ and NO in isolated rats aortic which were treated with NE,Ach and SNP were determined by the methods of nitric acid reductase and high-performance liquid chromatography(HPLC) with fluorescence detection(FD). Our results indicated that, compared with control group, (1) NE could dose-dependently constrict the isolated aortic rings, and also increased the endogenous SO₂ metabolites and NO levels in isolated aorta of rats. (2) Ach could dose-dependently relax the isolated aortic rings. The endogenous SO₂ metabolites level decreased but the NO level increased in isolated aorta treated with Ach. (3) SNP also could relax the isolated aortic rings in a dose-dependent way. Meanwhile, it increased the NO level and decreased the endogenous SO₂ metabolites level in isolated aorta of rats. These results led to the conclusion that level of SO₂ derivatives increased when blood vessel was constricted and decreased when vas was relaxed. Suggesting that endogenous SO₂ and its metabolites may modulate the tension of rats vas in vivo as a gasotransmitter molecule.