Metabolic and physiological differences between zero-flow and low-flow myocardial ischemia: effects of L-acetylcarnitine.
The metabolic and physiologic differences between low-flow and zero-flow ischemia of varying duration were compared in the isolated perfused rat heart. Hearts subjected to 60 and 90 minutes of zero-flow ischemia recovered less cardiac work than hearts subjected to low-flow ischemia. Low-flow ischemia caused a build-up of both myocardial long-chain acyl coenzyme A and acyl carnitine esters, while zero-flow ischemia produced no change in long-chain acyl carnitine and only a transient increase in long-chain acyl coenzyme A. High energy phosphate depletion was greater in zero-flow ischemia. Perfusion with excess free fatty acids decreased the recovery of cardiac work after low-flow ischemia but had no effect after repeated episodes of zero-flow ischemia. L-Acetylcarnitine improved the recovery of cardiac work after low-flow ischemia in hearts perfused with 0.4 and 1.2 mM palmitate. With zero-flow ischemia, L-acetylcarnitine had no effect on the recovery of cardiac work in hearts perfused with 0.4 mM palmitate and a slight but statistically significant effect with 1.2 mM palmitate. Possible protective mechanisms of L-acetylcarnitine against ischemic damage are discussed.
D000105:Acetyl Coenzyme A / Q000378:metabolism; D000108:Acetylcarnitine / Q000494:pharmacology*; D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D002302:Cardiac Output / Q000187:drug effects; D002331:Carnitine / Q000031:analogs & derivatives* / Q000378:metabolism; D003326:Coronary Circulation / Q000187:drug effects*; D003327:Coronary Disease / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects*; D005227:Fatty Acids / Q000378:metabolism; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains
D000227:Adenine Nucleotides; D005227:Fatty Acids; D000108:Acetylcarnitine; D000105:Acetyl Coenzyme A; D002331:Carnitine