The Effects of Coronary Reperfusion on Sarcolemmal Na^+, K^+-ATPase Activity in Dogs

After the ligation of coronary artery for 1 hour (1-hr group), 2 hours (2-hr group) and 4 hours (4-hr group), we investigated myocardial viability through the alterations in sarcolemmal function with measurements of regional myocardial blood flow (RMBF) and sarcolemmal Na^+, K^+-ATPase (ATPase) activity, comparing these groups with a permanently occluded group (permanent group). RMBF was measured in the ischemic region using hydrogen gas generated by electrolysis. Sarcolemmal membrane debris was prepared from ischemic, marginal and non-ischemic regions of the myocardium 7 days after reperfusion. Seven days after reperfusion, RMBF in 1-hr group recovered to control value. Reduction of RMBF in 2-hr group was significantly less than that of RMBF in parmanent group. There was no significant difference in RMBF between 4-hr group and permanent group. In the ischemic region, reduction of ATPase activity in 1-hr 2-hr group was significantly less than that of enzyme activity in permanent group. There was no difference in enzyme activity between 4-hr agoup and permanent group. In the marginal region, there was no difference in ATPase activity between the reperfusion group and the permanent group. These results show that in 4 hours or more after coronary artery occlusion, little salvage of the myocardium can be induced by acute reperfusion.