H-1-NMR MEASUREMENT OF TRIACYLGLYCEROL ACCUMULATION IN THE POST ISCHEMIC CANINE HEART AFTER TRANSIENT INCREASE OF PLASMA-LIPIDS

This study tests the hypothesis that increased levels of plasma lipids can accelerate accumulation of myocardial triacylglycerols in post-is chemic but viable myocardium. Two groups of dogs underwent 90 min of l eft anterior descending coronary artery (LAD) occlusion followed by 24 0 min of reperfusion. The first group of saline-treated dogs (n=7) had physiological levels of plasma lipids during reperfusion; a second gr oup treated with Liposyn and heparin (n=5) experienced increased plasm a lipids during reperfusion. The transmural content of triacylglycerol s was determined during ischemia and reperfusion using H-1 NMR one-dim ensional chemical shift imaging (1D CSI), and at the end of reperfusio n using Oil Red-O staining and chemical assay. TTC staining was used t o identify the extent of irreversibly injured myocardium. Subepicardia l and plasma triacylglycerol content, measured both by 1D CST and chem ically, did not change during reperfusion in saline-treated dogs. Infu sing dogs with Liposyn and heparin for 90 min during reperfusion trans iently elevated their plasma triacylglycerols, which returned to norma l levels following Liposyn wash-out, During Liposyn wash-out, myocardi al triacylglycerols measured by 1D CSI preferentially increased in the subepicardium of area-at-risk myocardium (P<0.05). Triacylglycerol co ntent, measured chemically, also increased in area-at-risk compared to non-ischemic subepicardium (P<0.001). Significant endocardial damage occurred in both groups, but elevated levels of plasma lipids did not increase the size of the area-at-risk. Therefore, elevated plasma lipi ds caused a preferential accumulation of triacylglycerols in area-at-r isk myocardium during reperfusion without exacerbating irreversible is chemic injury, These results are consistent with either inhibited fatt y acid oxidation or mis-matched fatty acid extraction and oxidation in area-at-risk myocardium. (C) 1997 Academic Press Limited.