Calcium concentration in hepatocytes during liver ischaemia-reperfusion injury and the effects of diltiazem and citrate on perfused rat liver

Objective To clarify the role of the calcium concentration in hepatocytes in liver ischaemia-reperfusion injury in relation to the protective effect of calcium-related agents. Design Serial calcium concentrations of extramitochondrial cytosolic sites (EMCa) and in mitochondria (MCa) in hepatocytes of isolated perfused rat liver were measured by an electron probe X-ray microanalyser, and the effects of calcium-related agents were evaluated. Methods Ischaemia was induced for 2 h, followed by 2 h of reperfusion in group 1 (without drug), group II (with diltiazem, 9.3 mu M) and group III (with citrate, 5 mM), Results In group I, EMCa increased rapidly after reperfusion (before ischaemia, 2.0 mmol/kg wet weight; 1 min after reperfusion, 4.4 mmol/kg), and MCa increased (before ischaemia, 2.6 mmol/kg; 1 min after reperfusion, 5.07 mmol/kg). Thereafter the levels decreased, but remained high at 120 min after reperfusion in group I (EMCa, 3.2 mmol/kg, MCa 4.1 mmol/kg), At 1 min after reperfusion, EMCa in group III (2.9 mmol/kg) and MCa in groups II (3.4 mmol/kg) and III (4.0 mmol/kg) were significantly lower than in group I. At 120 min after reperfusion, the EMCa and MCa in groups II (2.5 and 3.1 mmol/kg, respectively) and III (2.4 and 3.0 mmol/kg, respectively) remained at significantly lower levels. Mitochondrial function in groups II and III was better preserved than in group I. The levels of hepatic enzymes in the perfused fluid of group III were lower than in group I. Conclusions Calcium concentration in hepatocytes may play an important role in ischaemia - reperfusion injury. Diltiazem and citrate demonstrated a protective effect by maintaining a low calcium level in hepatocytes. Eur J Gastroenterol Hepatol 12:291-297 (C) 2000 Lippincott Williams & Wilkins.