Myocardial protection by antioxidant during permanent and temporary coronary occlusion in dogs

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Abstract
In an ischaemic heart model the lipid peroxidation, scavenger state and ultrastructure were studied, to determine the action of a new antioxidant of dihydroquinoline type (MTDQ-DA). In dog experiments, the left descending coronary artery (LAD) was ligated permanently (30 minutes, 1, 2 or 3 hours) or temporarily (30 minutes, 1 or 2 hours of ischaemia followed by 1 hour of recirculation). The experimental protocol involved two groups: control animals without antioxidant treatment and animals treated with antioxidant infusion during the ischaemic and reperfusion period. In both groups, the thiobarbituric acid reactive product, the malondialdehyde (MDA), reduced glutathione (GSH) and superoxide dismutase (SOD) were measured, to illustrate the injured or scavenged state of the membrane system. In nontreated animals the permanent and temporary LAD increased the MDA content, decreased GSH concentration (mainly during reperfusion) and reduced SOD activity. Treatment with MTDQ-DA diminishes the characteristic biochemical changes. According to ultrastructural investigations, irreversible alterations (Ca deposits in the mitochondria, disruption of intramitochondrial membranes, hypercontraction bands) occurred only in the control group. Antioxidant therapy is able to reduce the myocardial damages both quantitatively and qualitatively.