Fatty acylcarnitine accumulation and membrane injury in ischemic canine myocardium

Role of fatty acid metabolites in the development of myocardial ischemic damage

1. The review deals with possible mechanisms by which fatty acids amplify ischemic damage in myocardium. 2. The accumulation of free fatty acids, long chain acyl CoA and carnitine esters during hypoxia and their effects on various enzymatic systems are discussed. 3. Findings on the influence of exogenous fatty acids as well as observations concerning an inhibition of fatty acid degradation are also considered. 4. Finally the role of an oxygen steal effect, as an indirect mechanism for the fatty acid induced amplification of ischemic damage, is discussed.

Protective role of intracoronary fatty acid binding protein in ischemic and reperfused myocardium

In this study, fatty acid binding protein was used to protect an ischemic heart from reperfusion injury. Isolated rat heart was preperfused in the presence of 1.4 microM liposome-bound fatty acid binding protein for 15 minutes, followed by 30 minutes of ischemia and 30 minutes of reperfusion. Our results indicated better preservation of myocardial high-energy phosphate compounds (including ATP and creatine phosphate), reduced creatine kinase and lactate dehydrogenase release from the heart, and improved coronary flow in hearts treated with fatty acid binding protein compared with untreated controls. Fatty acid binding protein enhanced reacylation of arachidonic acid into phospholipids, thereby preserving membrane phospholipids and reducing free fatty acid contents during ischemia and reperfusion. In addition, fatty acid binding protein-bound long-chain free fatty acids and their thioesters as well as carnitine esters were increased in the cytosolic compartment of the heart. These results suggest that fatty acid binding protein may be used as a possible therapeutic agent to improve myocardial function during reperfusion of ischemic heart.

Nuclear magnetic resonance study of high-energy phosphate stores in models of adriamycin cardiotoxicity

Previous studies have suggested that one of the mechanisms of adriamycin (ADR) cardiomyopathy is depletion of high-energy phosphate stores (HEP). To examine this hypothesis, we used 31P nuclear magnetic resonance to assess the adenosine triphosphate-to-phosphocreatine ratio (ATP-to-PCr ratio) in Langendorff-perfused rabbit hearts. Using either an acute (5 days of therapy at 5 mg/kg/day) or chronic model (7 to 10 weeks of therapy at 1.2 or 1.5 mg/kg twice a week), we compared isovolumetric LV systolic pressure, heart rate, ATP-to-PCr ratios, and histologic lesions between the treated and control animals in each model. In the acute model, there was a significant increase in the ATP-to-PCr ratio (P less than 0.02), without significant changes in myocardial function. Despite significant hemodynamic and histologic alterations in the chronic model, compared to controls, we were unable to identify significant differences in ATP-to-PCr ratios. We conclude that there appear to be differences in energy metabolism between the acute cardiotoxicity and the chronic cardiomyopathy of ADR in the rabbit model and the mechanism of the chronic cardiomyopathy from ADR therapy does not appear to be related to progressive impairment of cellular high-energy phosphate metabolism as measured by the ATP-to-PCr ratio.

Effects of POCA on metabolism and function in the ischemic rat heart

Sodium 2-[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (POCA) inhibits carnitine palmityltransferase I and fatty acid oxidation. The effects of POCA on cardiac function and on tissue levels of carnitine and coenzyme A esters were studied in the isolated rat heart subjected to 90 minutes of ischemia with and without 15 minutes of reperfusion. The perfusion medium contained 1.2 mM palmitate and 5.5 mM glucose plus or minus 0.5 mM POCA. This compound prevented accumulation of long-chain acylcarnitine and coenzyme A esters during ischemia and significantly improved the recovery of cardiac output after ischemia and reperfusion. Short-chain acylcarnitine levels were increased during ischemia by POCA. No effects were noted on tissue ATP and lactate levels. POCA may protect the ischemic heart by preventing accumulation of these toxic metabolites and by stimulating glucose utilization during ischemia.

Effect of carnitine on myocardial function and metabolism following global ischemia

Carnitine has therapeutic potential for the postischemic heart by facilitating the oxidation of acylated fatty acid metabolites, the intracellular accumulation of which has a deleterious effect on myocardial function and metabolism. To test this hypothesis, two groups of dogs were given preischemic treatment with carnitine, 50 mg per kilogram of body weight (Group 1) or 100 mg/kg (Group 2), and were compared with untreated controls (N = 12 for all groups). The canine hearts underwent 30 minutes of global 37 degrees C ischemic arrest with reperfusion. Left ventricular systolic and diastolic function was assessed by an intracavitary balloon while metabolic derangements were quantitated by serial myocardial biopsies assayed for adenosine triphosphate (ATP). Comparable 49 to 53% (p less than 0.01) declines in preischemic ATP levels occurred during the study period in the controls and both experimental groups. However, postischemic systolic left ventricular function was better preserved in Group 2: these hearts generated 61 +/- 3% of preischemic peak developed pressure compared with 37 +/- 4% in the controls and 42 +/- 3% in Group 1 (p less than 0.01 for each), and 60 +/- 2% of preischemic maximum rate of rise of left ventricular pressure as opposed to 45 +/- 4% in the controls and 49 +/- 6% in Group 1 (p less than 0.02 for each).(ABSTRACT TRUNCATED AT 250 WORDS)