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 +/- 1.4 mumol/wet.g, p < 0.01), and remained reduced in 30-RP (3.0 +/- 0.6 mumol/wet.g, p < 0.01). On the other hand, the concentration 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 mumol/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.