RESUMO
BACKGROUND: The aim was to assess the effect of trimetazidine (TMZ) on mitochondrial alterations induced in a canine model of brief, repeated episodes of ischemia. MATERIAL/METHODS: Twelve crossbred dogs were analyzed, after double-blind randomization, to a 7-day treatment with either TMZ or placebo. Twenty brief, complete occlusions of the left anterior descending coronary artery were performed. Mitochondrial analysis entailed a qualitative (percentage of mitochondrial damage, merging, pairing, vacuoles, and lipofucsin granules) and a quantitative size analysis (major and minor axes, perimeter, and area) of the mitochondria in the ischemic and control zones. RESULTS: Comparative study of the control zones revealed an increase in lipofucsin granules in the TMZ series and a greater percentage of damaged mitochondria and vacuoles. The control-zone mitochondria treated with TMZ presented a significant increase in the perimeter and major axis and a decrease in the minor axis (p<0.005). No significant differences were found between the series in the qualitative analysis of mitochondrial damage in the ischemic zone. The mitochondria in the TMZ series presented a greater major axis and perimeter than those in the placebo series (p<0.05), which presented a smaller minor axis. CONCLUSIONS: TMZ made the mitochondria adopt an elongated, "rod-like" morphology in both the control and ischemic zones. This is interpreted as an increase in the membrane surface. In the non-ischemic zone, TMZ produced an increase in mitochondrial turnover. There were no differences in the myocardium subjected to ischemia in both series in terms of observable mitochondrial damage.
