The major findings of this study include: (1) mild HHcy caused hypertension in multiparous rats; (2) NAD(P)H oxidase-derived superoxide production was significantly increased without an apparent increase in antioxidants and antioxidant enzymes; (3) increased superoxide attenuated the ability of BK or Cch to regulate MVO2 in vitro, and this effect was restored by antioxidant treatment; and (4) cardiac gene expression profile differed between HHcy and control groups. This evidence concerns the gene KNG1 and hypertensive disorder.