Effects of carnitine on cardiac function after cardioplegic ischemia in neonatal rabbit hearts.
BACKGROUND
Ischemia immediately impairs myocardial fatty acid metabolism and reduces the concentration of carnitine which is an essential cofactor for fatty acid metabolism in the mitochondria. The purpose of this study was to investigate the effects of carnitine administration on recovery of cardiac function after cardioplegic ischemia in the neonatal heart where fatty acid metabolism is not a predominant source of adenosine triphosphate.


METHODS
Isolated blood-perfused neonatal rabbit hearts underwent 3 hours of cold cardioplegic ischemia. The control group (n = 10) was reperfused with unmodified diluted blood. The carnitine group (n = 10) was reperfused with the blood containing 5 mM/L of carnitine. Before ischemia (base line) and after 15 and 30 minutes reperfusion, left ventricular (LV) function and LV compliance were measured using a intraventricular conductance catheter combined with an isovolumic balloon. Coronary blood flow was measured and myocardial oxygen consumption was calculated.


RESULTS
Carnitine significantly improved not only LV systolic function but also LV diastolic function (p < 0.05) as well as LV compliance after ischemia. Coronary blood flow and myocardial oxygen consumption were significantly improved after ischemia in the carnitine group compared with the control group (p < 0.05).


CONCLUSIONS
These results suggest that carnitine strikingly improves LV functional recovery and aerobic metabolism after cold cardioplegic arrest, and may improve cardiac performance in neonates after open heart surgery.
Nemoto
S
S
Department of Pediatric Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical University. snemoto@bcm.tmc.edu
Aoki
M
M
Dehua
C
C
Imai
Y
Y
D000818:Animals; D000831:Animals, Newborn; D002331:Carnitine / Q000494:pharmacology*; D003326:Coronary Circulation; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D006324:Heart Arrest, Induced; D017202:Myocardial Ischemia / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption; D011817:Rabbits; D016277:Ventricular Function, Left / Q000187:drug effects*
D002331:Carnitine