The effect of L-carnitine on myocardial protection in cold cardioplegia followed by reperfusion.
We studied the effect of exogenous L-carnitine on myocardial viability and carnitine uptake following ischemia-reperfusion in isolated rat hearts. Hearts were subjected to hypothermic cardioplegia at 26 degrees C for 80 minutes with and without carnitine 10 mmol/L added to the perfusate and cardioplegic solution [Groups I (n = 9) and II (n = 14), respectively]. Additionally, to study myocardial carnitine uptake, hearts were subjected to global ischemia at 20 degrees C [Group III (n = 6) and IV (n = 6)] and at 37 degrees C [Group V (n = 6) and VI (n = 6)] with and without carnitine 10 mmol/L added to the perfusate. All hearts received normothermic reperfusion, and Krebs-Henseleit solution was used as the perfusate in all groups. Postischemic aortic flow, expressed as the percentage of pre-ischemic flow, morphometric scores of myocardial mitochondria, and the myocardial concentration of adenosine triphosphate at the end of reperfusion were significantly higher in Group I than in Group II. In hearts treated with L-carnitine both at 20 degrees C and 37 degrees C the myocardial concentrations of carnitine fractions (free, short-acyl, and long-acyl) increased significantly compared to those in hearts without L-carnitine treatment. The myocardial concentration of free carnitine at the end of reperfusion was significantly higher in Group III than at pre-ischemia. These results suggest that exogenous L-carnitine is incorporated into cellular metabolism, even in hypothermic cardioplegia, improving cardiac function and preserving the myocardial adenosine triphosphate concentration.
Department of Thoracic-Cardiovascular Surgery, Tokyo Medical and Dental University, School of Medicine, Japan.
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T
Nakagawa
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Sunamori
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A
Suzuki
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002331:Carnitine / Q000493:pharmacokinetics / Q000494:pharmacology*; D006324:Heart Arrest, Induced; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D007036:Hypothermia, Induced; D008297:Male; D008929:Mitochondria, Heart / Q000473:pathology / Q000502:physiology; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar
D000255:Adenosine Triphosphate; D002331:Carnitine