Biologic effects of parenteral bisulfite on human vascular tissue

Antioxidant properties of bisulfite are used to stabilize parenteral amino acid solutions. After reports of adverse reactions to dietary sulfites, we evaluated whether the infusion of bisulfite had biologic effects on human vascular tissue. Because an endothelial oxidative injury can affect mediators of vasoreactivity, vascular pressure and prostaglandin production were studied in an intact human vein model infused with clinically relevant amino acid solutions differing only by their metabisulfite content (0 versus 300 mg/L). The amino acid solution containing bisulfite presented higher venous pressure (p < 0.01) and prostaglandin production (6-keto-prostaglandin F1 alpha, p < 0.01; and prostaglandin E2, p < 0.05). A hydroxyl radical-generating system added to the solutions did not modify the pressure readings, but it resulted in an overall decrease in prostacyclin production (p < 0.05). Despite this known inhibitory effect on oxidative challenge on prostaglandin I2 production, prostaglandins remained higher in the presence of bisulfite. The results suggest that the effect of bisulfite takes place before prostaglandin H2 synthesis in the eicosanoid cascade, whereas the oxidative challenge affects specifically the synthesis of prostaglandin I2, after prostaglandin H2, indicating that there is no interaction between bisulfite and the hydroxyl generating system. Bisulfite has local vascular effects on endothelial mediators, separate from its antioxidant properties.