Examination of the Direct Effects of Antianginal Agents on the Hypoxic Canine Myocardium

Abstract

The myocardial protective effect of nicorandil, N-(2-hydroxyethyl) nicotinamide nitrate ester, against hypoxia was examined in comparison with that of nitroglycerin in 22 open chest dogs. The regional ventricular myocardium was perfused for 5 min with a hypoxic solution in 8 dogs (Group 1), with a hypoxic solution containing 0.5 or 2.5mg/dl of nicorandil in 7 dogs (Group 2) and with a hypoxic solution containing 0.5mg/dl of nitroglycerin in 7 dogs (Group 3). In Group 2, the ATP content of the hypoxic myocardium was 3.14±0.37μmol/g, which was less than that in the uninvolved myocardium (4.31±0.57μmol/g) but significantly higher than those of the hypoxic myocardium in Groups I and 3 (2.09±0.45 and 2.39±0.33μmol/g, respectively). The lactate content of the hypoxic myocardium in Group 2 (5.05±1.13μmol/g) was less than those of the hypoxic myocardium in Groups 1 and 3 (8.77±2.34 and 8.98±2.08μmol/g, respectively). This protective effect was not caused by the hemodynamic changes. In contrast, nitroglycerin did not show any protective effects on the hypoxic myocardium.