Effects of lipids on the functional and metabolic recovery from global myocardial stunning in isolated rabbit hearts

OBJECTIVES: High concentrations of free fatty acids may increase myocardial ischaemic damage. However, the administration of lipid emulsions during reperfusion improves the functional recovery of stunned myocardium. From this apparent controversy we hypothesise that the effect of lipids is related to the time of its administration: we compared the effects of pre- and post-ischaemic administration of Intralipid((R)) on stunned myocardium. We also examined the role of fatty acids and phospholipids, respectively, in the effect of lipid emulsions on stunned myocardium. METHODS: Myocardial stunning was produced by 15 min of ischaemia and 90 min of reperfusion in isolated blood perfused rabbit hearts. Intralipid((R)) was administered either prior to ischaemia or during reperfusion. Left ventricular pressure (LVP) and its first derivative (LVdP/dt) were measured to assess functional recovery. High energy phosphates were measured with HPLC. The effects of linoleic acid, phosphatidylcholine and their combination were also studied. RESULTS: Only when Intralipid((R)) was administered during reperfusion, it improved recovery from contractile function and increased high energy phosphate content in globally stunned myocardium. Both linoleic acid and phosphatidylcholine significantly improved myocardial function in stunned myocardium. CONCLUSIONS: The effect of lipids on the contractile performance and metabolic state of stunned myocardium depends mainly on the timing of its administration with regard to the ischaemia/reperfusion event. Both free fatty acids and phospholipids contribute to the beneficial effect of lipid emulsions on functional recovery of stunned myocardium.