Pre-treatment with trimetazidine increases sarcolemmal mechanical resistance in reoxygenated myocytes

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Abstract

Objective: Cytoskeletal and sarcolemmal fragility secondary to anoxia may contribute to sarcolemmal rupture and cell death during reoxygenation of cardiomyocytes. This study investigated the influence of trimetazidine (TMZ), a drug with effects on lipid metabolism and cell membranes, on reoxygenation-induced sarcolemmal rupture. Methods: Isolated adult rat myocytes were submitted to 60 min of metabolic inhibition and 5 min of hypo-osmotic reoxygenation to simulate reperfusion edema in situ. Cells were allocated to 3 groups of treatment: in one group, TMZ 100 μmol/l was added to bath the metabolic inhibition and reoxygenation buffers (group TMZ); another group was submitted to the same treatment but cells had previously been incubated with TMZ 100 μmol/l for 3 h (group TMZ-Pre); a control group underwent metabolic inhibition and hypo-osmotic reoxygenation without any treatment. Cell morphology was monitored throughout the experiment and sarcolemmal integrity was assessed by quantification of LDH activity and trypan blue exclusion test. Results: After 60 min of metabolic inhibition most cells (83.1 ± 2%) presented rigor contracture without between-group differences. Reoxygenation resulted in hypercontracture of 84.2 ± 2.3, 91.2 ± 1.4 and 84.1 ± 2.1% of cells in TMZ, TMZ-Pre and control groups, P = NS. The trypan blue exclusion test revealed a higher proportion of cells with sarcolemmal integrity in TMZ and TMZ-Pre groups than in controls (12.7 ± 2.0, 10.0 ± 1.5 and 6.3 ± 0.8%, respectively, P = 0.002). No between-group differences in LDH activity in the extracellular medium were observed at the onset or at the end of metabolic inhibition. However, LDH release was significantly lower (P = 0.002) in the TMZ-Pre group (1.6 ± 0.1 IU/1000 cells) than in the TMZ and control groups (1.9 ± 0.2 and 2.2 ± 0.1 IU/1000 cells). Conclusion: Preincubation of cardiomyocytes with TMZ does not prevent rigor contracture induced by metabolic inhibition or hypercontracture during subsequent reoxygenation, but does improve sarcolemmal resistance to reoxygenation-induced mechanical stress. This could help to explain the beneficial effect of TMZ on infarct size.

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Ruiz-Meana, M., Garcia-Dorado, D., Juliá, M., González, M. A., Inserte, J., & Soler-Soler, J. (1996). Pre-treatment with trimetazidine increases sarcolemmal mechanical resistance in reoxygenated myocytes. Cardiovascular Research, 32(3), 587–592. https://doi.org/10.1016/0008-6363(96)00112-5

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