EVALUATION OF POST-ISCHEMIC MYOCARDIAL METABOLISM BY ^1H-MAGNETIC RESONANCE SPECTROSCOPY IN THE RABBIT HEART

To assess myocardial metabolism during ischemia and reperfusion, 36 rabbits were divided into 4 groups; a control group (Control), an ischemia group in which the circumflex branch was ligated for 30 min (Ischemia), a 5 min reperfusion group (5-RP) and a 30 min reperfusion group (30-RP). The concentrations of metabolites (lactate, alanine and free-carnitine) in the myocardium determined by 1H-magnetic resonance spectroscopy (MRS). The concentration of free carnitine was lower in Ischemia than in Control (2.0±0.4 vs 5.2±1.4μmol/wet·g, p<0.01), and remained reduced in 30-RP (3.0±0.6μmol/wet·g, p<0.01). On the other hand, the concentrations of lactate and alanine were higher in Ischemia than in those of Control (54.9±8.5 vs 8.8±0.8, 6.5±1.0 vs 2.5±0.5 μmol/wet·g, respectively; p<0.01), and remained elevated in 30-RP. These findings indicate that recovery from an ischemia-induced disturbance in myocardial metabolism to the pre-ischemic level apparently requires a prolonged period after reperfusion, and that 1H-MRS is a useful new method for evaluating myocardial ischemia.