Cardiac Venous Endothelial Dysfunction After Myocardial Ischemia and Reperfusion in Dogs

Endothelial dysfunction is a prominent occurrence in coronary arteries after myocardial ischemia and reperfusion. However, this has not been studied in coronary veins. Endothelium-dependent vasorelaxation was studied in cardiac venous rings obtained from dogs subjected to 60 min of coronary artery occlusion followed by 270 min of reperfusion, as well as from dogs subjected to sham ischemia-reperfusion. Myocardial ischemia resulted in a 96 +/- 2% decrease in coronary flow to the ischemic area 60 min after occlusion of the left anterior descending (LAD) coronary artery, which led to a significant degree of cardiac necrosis (i.e., 32.9 +/- 3.9% of area at risk). Cardiac venous rings isolated from sham ischemia-reperfusion dogs relaxed 68 +/- 3% to 200 microM ADP, 65 +/- 3% to 2 microM A23187, and 76 +/- 4% to 200 microM sodium nitrite (NaNO2). Corresponding values for cardiac venous rings isolated from ischemic-reperfused dogs were 32 +/- 3% for 200 microM ADP (P less than 0.01 vs. sham), 31 +/- 3% for 2 microM A23187 (P less than 0.01 vs. sham), and 74 +/- 3% for 200 microM NaNO2 (NS from sham). In rings from control dogs, vasorelaxation to ADP and A23187 was markedly inhibited by 4 mM NG-methyl-L-arginine (L-NMMA) and 10 methylene blue and restored after NG-nitro-L-arginine by 3 mM L-arginine. These results demonstrate that a significant degree of endothelial dysfunction occurred in cardiac venous rings after ischemia and reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)