Sodium metabisulfite (SMB) is most commonly used as the preservative in many food preparations and drugs. So far, few studies about its negative effects were reported. The purpose of this study was to investigate the effect of SMB on the expression of big-conductance Ca2+-activated K+ (BKCa), ATP-sensitive K+ (K-ATP), and L-type calcium (L-Ca2+) channels in rat aorta in vivo and in vitro. The results showed that the mRNA and protein levels of the BKCa channel subunits alpha and beta 1 of aorta in rats were increased by SMB in vivo and in vitro. Similarly, the expression of the K-ATP channel subunits Kir6.1, Kir6.2, and SUR2B were increased by SMB. However, SMB at the highest concentration significantly decreased the expression of the L-Ca2+ channel subunits Ca(v)1.2 and Ca(v)1.3. These results suggest that SMB can activate BKCa and K-ATP channels by increasing the expression of alpha, beta 1, and Kir6.1, Kir6.2, SUR2B respectively, while also inhibit L-Ca2+ channels by decreasing the expression of Ca(v)1.2 and Ca(v)1.3 of aorta in rats. The molecular mechanism of SMB-induced vasorelaxant effect might be related to the expression changes of BKCa, K-ATP, and L-Ca2+ channels subunits. Further work is needed to determine the relative contribution of each channel in SMB-mediated vasorelaxant effect. (C) 2014 Elsevier B.V. All rights reserved.