Hypoxic Preconditioning of Isolated Cardiomyocytes of Adult Rat
The present study was undertaken to examine whether or not cytoprotective effects of hypoxic preconditioning were detectable in isolated, quiescent cardiomyocytes of adult rats. The cardiomyocytes were incubated for 120 minutes under hypoxic condtions (sustained hypoxia), followed by 15-minute reoxygenation. Sustained hypoxia decreased the number of viable cells (from 99% to 70% of the initial cell), which consisted of rod- and square-shaped cardiomyocytes. It also decreased the number of rod-shaped cardiomyocytes (from 90% to 40% of the initial cell) and simultaneously increased the number of square-shaped cells (from 10% to 30% of the initial cell). Fifteen-minute reoxygenation resulted in a further decrease in the numbers of viable cells (less than 50% of the initial cell) and square-shaped cells (10% of the initial cell), whereas it did not change the number of rod-shaped cells. Hypoxia-reoxygenation also induced a release of purine nucleosides and bases (ATP metabolites) into the incubation medium. When the cardomyocytes were subjected to 20 minutes of hypoxic incubation, followed by 30 minutes of normoxic incubation (hypoxic preconditioning), sustained hypoxia-induced decreases in the numbers of viable cells and rod-shaped cells were attenuated (80% and 60% of the initial cell, respectively). The intervention also attenuated sustained hypoxia-induced increase in the number of square-shaped cells (18% of the initial cell). The number of rod-shaped cells subjected to hypoxic preconditioning at the end of 15-minute reoxygenation was similar to that at the end of sustained hypoxia, whereas the number of square-shaped cells decreased to 10% of the initial cells, which was similar to that of square-shaped cells without hypoxic preconditioning. The intervention also suppressed the release of ATP metabolites during hypoxia-reoxygenation.
KeywordsIschemic Precondition Hypoxic Precondition Isolate Rabbit Heart Hypoxic Incubation Sustained Hypoxia
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