EFFECT OF ACIDOTIC BLOOD REPERFUSION ON REPERFUSION INJURY AFTER CORONARY-ARTERY OCCLUSION IN THE DOG HEART

A prolongation of the intracellular acidosis after myocardial ischemia can protect the myocardium against reperfusion injury. In isolated he arts, this was achieved by prolongation of the extracellular acidosis. The aim of this study was to investigate whether regional reperfusion with acidotic blood after coronary artery occlusion can reduce infarc t size and improve myocardial function in vivo. Anesthetized open-ches t dogs were instrumented for measurement of regional myocardial functi on, assessed by sonomicrometry as systolic wall thickening (sWT). Infa rct size was determined by triphenyltetrazolium staining after 3 h of reperfusion. The left anterior descending coronary artery (LAD) was pe rfused through a bypass from the left carotid artery. The animals unde rwent 1 h of LAD occlusion and subsequent bypass-reperfusion with norm al blood (control, n = 6) or blood equilibrated to pH = 6.8 by using 0 .1 mM HCl during the first 30 min of reperfusion (HCl, n = 5). Regiona l collateral blood flow (RCBF) at 30-min occlusion was measured by usi ng colored microspheres. There was no difference in recovery of sWT in the LAD-perfused area between the two groups at the end of the experi ments [-2.8 +/- 1.2% (HCl) vs. -4.4 +/- 2.5% (control); mean +/- SEM; p = NS]. RCBF was comparable in both groups. Infarct size (percentage of area at risk) was reduced in the treatment group (12.8 +/- 2.8%) co mpared with the control group (26.2 +/- 4.8%; p < 0.05). These results indicate that reperfusion injury after coronary artery occlusion can be reduced by a prolonged local extracellular acidosis in vivo.