Sulfur Dioxide: Sulfite

Abstract

The chemistry of sulfite-bisulfite (the hydrate of sulfur dioxide in mammalian plasma and serum was investigated in vitro and in vivo. The longevity of sulfite in contact with mammalian plasma and known components of blood was determined by adaptation of a colorimetric method for sulfite analysis. Evidence from all experiments indicated that, under physiological conditions, sulfite reacts reversibly with disulfide bonds present in the plasma resulting in formation of S-sulfonates (sulfitolysis). Free sulfite was not detected in plasma of rabbits immediately following exposure to approximately 25 ppm SO₂, but there was good evidence for substantial elevation of plasma and serum S-sulfonate content. Reactivity of sulfite with plasma constituents may protect many body tissues from the insult of relatively high concentrations of sulfite and may facilitate prolonged exposure to very low levels of sulfite.