To determine whether infused ATP-MgCl2 affects mitochondrial adenine nucleotide translocase (ANT) activity, free fatty acids (FFAs) and Ca2+ levels, total hepatic ischemia in rats was produced for 90 min after which blood flow was allowed to return to the liver. Immediately on reflow, the animals received intravenously 0.5 ml of either saline, ATP-MgCl2 (12.5 μmol), or dopamine (6 mg/kg). Three hours after ischemia and reflow, hepatic mitochondrial FFAs and Ca2+ levels increased; however, ATP-MgCl2 infusion significantly lowered FFAs and restored Ca2+ levels. The depressed mitochondrial ANT activity was somewhat improved but not restored by circulatory support with dopamine; however, ATP-MgCl2 infusion following ischemia restored that activity. Thus the present results suggest that the improved organ function that occurs with ATP-MgCl2 infusion following ischemia may be mediated through an improvement in ischemia-induced mitochondrial function.