Blood pressure of rats lowered by sulfur dioxide and its derivatives

This study was designed to investigate effects of sulfur dioxide (SO(2)) and its derivatives (bisulfite and sulfite) on the rat blood pressure. The blood pressures of male Wistar rats exposed to SO(2) and its derivatives at various doses were measured. Findings were that: (1) with acute-one time exposure to SO(2) for 6 h, the rat blood pressures were lowered in contrast to their controls and their background levels in a dose-dependent manner. (2) There were both a dose-response relationship and a time-response relationship between subchronic SO(2) exposure and the rat blood pressure. For SO(2) exposure at 10 ppm, first the blood pressures decreased significantly with exposure days in contrast to their controls and their background levels, and then these decreases became not significant, suggesting an adaption mechanism might be induced. However, SO(2) exposures at 40 ppm caused significant decreases of the blood pressures during the whole experiment, and no adaptation process was found. (3) SO(2) derivatives (bisulfite and sulfite) also caused the decreases of rat blood pressures in a dose-dependent manner. There are two conclusions: (1) Short-time, even acute one-time, exposure to SO(2) or its derivatives may cause a decrease of blood pressure of the animals in both dose-dependent and time-dependent manners. (2) SO(2) is a systemic toxic agent, not only to the respiratory system. SO(2) can cause at least functional damage to the cardiovascular system.