Reversible and irreversible ischaemic damage: importance of energy metabolism

In this study the effects of different degrees and duration of coronary flow reduction on pressure development of the isolated and perfused rabbit hearts has been studied. Three different degrees of ischaemia lasting for 30, 60 and 90 minutes have been investigated, after which the effects of post-ischaemic reperfusion have been followed. The effects of substituting FFA for glucose as myocardial substrate has also been investigated. Reperfusion resulted in a recovery of mechanical function or in a further worsening of mechanical function, depending upon the degree, duration of flow reduction and substrate employed. To establish the causes of reperfusion damage, in a separate series of experiments the effects of reperfusion after 90 minutes of severe ischaemia on lactate, CPK and Mg++ release, tissue and mitochondrial calcium content tissue ATP and CP concentration and mitochondrial function have been determined. The ultrastructural damage of the myocardial cell have also been established. The results obtained suggest that mitochondria play an important role in reperfusion damage.