SO2——一种神秘的生物小分子：SO2及其衍生物对血管张力的双相-双向性调节作用

为了探索二氧化硫(SO2)作为调节血管张力的细胞气体信号分子的可能性,采用SO2衍生物(亚硫酸钠和亚硫酸氢钠混合物,在中性液体中二者的摩尔比约为3:1)温育大鼠离体胸主动脉血管环的方法,观察SO2及其衍生物对血管环张力的影响.结果发现,SO2及其衍生物在低浓度(<1.35mmol·L-1)下可引起大鼠离体胸主动脉血管环收缩而不引起舒张;在高浓度(>1.35mmol·L-1)下先引起血管环收缩、后引起舒张;且这些变化均与血管内皮无关.这表明不同作用浓度相和不同作用时相,该化学物对血管张力的作用完全相反.由此得出结论:1)低浓度SO2及其衍生物是血管收缩因子;2)高浓度SO2及其衍生物对血管张力的影响是双相-双向性的.内源性的SO2及其衍生物的前体SO/SO2在体内的生理浓度比本研究的低浓度还要低1～2个数量级,其对血管张力的生理作用及其他的生物学作用尚需进一步研究.

SO2——A Secret Biological Small Molecule: The Biphasic Roles of SO2 and Its Derivatives on the Blood Vessel Tension

Recently we have found that SO2 and its derivatives at high concentrations may low rat blood pressure and cause the vasorelaxation by direct effect of the chemicals on aortic smooth muscle cells. It is not dependent on vascular endothelium, also is independent on nitric oxide(NO). In this paper, the effects of SO2 derivatives at low concentrations (0.10~1.35mmol·L-1) on tension of the rat isolated aortic rings were studied in vitro in order to explore whether or not SO2 might be a new gasotransmitter. Our results showed that SO2 and its derivatives at low concentrations(<1.35mmol·L-1)caused vasoconstriction of rat aortic rings in vitro; However, at high concentrations(>1.35mmol·L-1)firstly caused vasoconstriction of the rings, and then caused vasorelaxation. It is shown that at various exposed-concentration phases and at various exposed-time phases of the exposure of SO2 and its derivatives, effects of the chemicals on the blood vessel tension were absolute opposition: vasoconstriction or vasorelaxation. These results lead the conclusions: 1) SO2 and its derivatives at low concentrations are vasoconstrictor; 2) Effects of SO2 and its derivatives at high concentrations on the blood vessel tension are concentration-biphasic and time-biphasic. The physiological roles of the precursors of SO2 derivatives--SO/SO2 at physiological concentrations, which is much lower than 0.1mmol·L-1 like as in this present study, are not still known. The further study is needed in order to understand the role of SO/SO2 on the blood vessel tension and its other biological roles.