Effects of intravenous cariporide on release of norepinephrine and myoglobin during myocardial ischemia/reperfusion in rabbits.

To examine the effects of cariporide, a Na(+)/H(+) exchanger-1 inhibitor, on cardiac norepinephrine (NE) and myoglobin release during myocardial ischemia/reperfusion by applying a microdialysis technique to the rabbit heart. In anesthetized rabbits, two dialysis probes were implanted into the left ventricular myocardium and were perfused with Ringer's solution. Cariporide (0.3mg/kg) was injected intravenously, followed by occlusion of the left circumflex coronary artery. During 30-min coronary occlusion followed by 30-min reperfusion, four consecutive 15-min dialysate samples (two during ischemia and two during reperfusion) were collected in vehicle and cariporide-treated groups. Dialysate myoglobin and NE concentrations were measured by immunochemistry and high-performance liquid chromatography, respectively. Dialysate myoglobin and NE concentrations increased significantly during myocardial ischemia/reperfusion in both vehicle and cariporide-treated groups (P<0.01 vs. baseline). In cariporide-treated group, dialysate myoglobin concentrations were significantly lower than those in vehicle group throughout ischemia/reperfusion (P<0.01 at 0-15 min of ischemia, P<0.05 at 15-30 min of ischemia, P<0.01 at 0-15 min of reperfusion, and P<0.01 at 15-30 min of reperfusion). However, dialysate NE concentrations in cariporide-treated group were lower than those in vehicle group only during ischemia (P<0.01 at 0-15 min of ischemia, and P<0.05 at 15-30 min of ischemia). When administered before ischemia, cariporide reduces myoglobin release during ischemia/reperfusion and decreases NE release during ischemia.