HMOX1 and ischemia: Administration of 200 mg/kg/day metformin i.p. for 6 successive days before induction of ischemia and promptly at the onset of reperfusion to rats significantly decreased the hepatic nitrite level (Fig. 4A) and increased the hepatic HO-1 (Fig. 4B) and H2S (Fig. 4C) levels as compared to animals subjected to hepatic I/R.