1005-81 Myocardial Protection by Na+/H+ Exchange Inhibition in Ischemic, Reperfused Porcine Hearts

The protective effect of the Na+/H+ exchange inhibitor HOE 694 was tested in porcine hearts subjected to 45min of regional ischemia and 24 h of reperfusion. The compound (3mg/kg) was intravenously injected in 6 pigs each either 10 min before ischemia (group A) or 10 min before reperfusion (group B). Six animals served as controls. Apart from the main end-points, infarct size and regional systolic shortening, the effect of HOE 694 on global hemodynamic parameters which included coronary blood flow and coronary venous oxygen saturation was evaluated. Although the Na+IH+ exchange inhibitor did not affect global hemodynamics, preischemic treatment with HOE 694 decreased infarct size from 65±18% (control group) to 12 ± 9% (p < 0.01) and improved systolic shortening from 8 ± 6% (control group) to 28 ± 9% P < 0.02). In addition, increase in heart rate and myocardial contracture during early reperfusion were significantly attenuated in group A. Treatment of group B did not exhibit protective effects.ConclusionNa+/H+ exchange inhibition is a very protective means in myocardial ischemia and reperfusion when administered before ischemia. In this model, it was ineffective when given before reperfusion