Acute changes of myocardial norepinephrine and glycogen phosphorylase in ischemic and non-ischemic areas after coronary ligation in dogs.

Abstract

The myocardial norepinephrine (NE) content and glycogen phosphorylase activity were measured before and after coronary artery ligation in dogs anesthetized with pentobarbital. Coronary artery ligation was performed by ligating a branch of the left anterior descending coronary artery (LAD). Before coronary artery ligation, the NE content in the circumflex area (778.05 +/- 37.83 ng.g-1 wet tissue) was significantly higher than that in the LAD area (630.57 +/- 35.75 ng.g-1 wet tissue). The NE content in the circumflex area (non-ischemic area) decreased significantly 1.5, 3, 30. 60, and 420 min after coronary artery ligation, while that in the LAD area (ischemic area) did not decrease significantly except for the NE level obtained after 420 min of coronary artery ligation. The glycogen phosphorylase activity increased significantly 1.5 min after coronary artery ligation in both non-ischemic and ischemic areas. From the foregoing results, it is suggested that NE release occurs in both ischemic and non-ischemic areas within at least 1.5 min after coronary artery ligation, and that within 60 min after coronary artery ligation the NE content decreases in the non-ischemic area but not in the ischemic area probably because of very limited washout of the released NE in the ischemic area.