| Summary: | Myocardial ischemia-reperfusion (I/R) injury is an important health concern in myocardial infarction and situations such as angioplasty and cardiac surgeries. Therefore, patients and physicians need therapeutic interventions that are applicable at the time of surgery. Flavonoids and ascorbate (vitamin C) are known for their antioxidant activity and may be involved in the currently known health benefits of plant based foods and drinks. The objectives of this study were to 1) determine the extent to which ascorbate or catechin alone at levels which could be in blood after dietary supplementation, can protect myocardial tissue in the reperfusion phase of I/R injury, and 2) evaluate the possible cooperative or synergistic protective effect of ascorbate and catechin when given together. Isolated rat hearts (n=48) were perfused in the retrograde mode with modified Krebs-Henseleit buffer, and following the induction of 30 min global ischemia, ascorbate (150 µM) and/or catechin (5 µM) were added directly into the perfusate during 90 min reperfusion. To determine the histopathological features, hematoxylin and eosin (H&E) stain was used in one heart per condition; while to assess the biochemical analysis, the heart tissues were assessed for apoptosis (caspase-3 activity), oxidative stress (thiobarbituric acid reactive substances (TBARS) and total malondialdehyde (MDA) levels), and redox status (reduced and oxidized glutathione tissue levels). A comparison of IR hearts with two controls, sham (perfused for a 15 min stabilization period) and continuous perfusion (perfused for 135 min), showed in most but not all measurements that this was a suitable model of IR injury. The treatment experiments showed that 150 µM ascorbate protected the heart against lipid peroxidation and cell apoptosis by 100%, while 5 µM catechin protected by 67% and 90% respectively. No cooperative protective effect could be observed when ascorbate and catechin were used together. None of the treatments significantly affected either reduced or oxidized glutathione levels. In conclusion, this study showed strong protection by ascorbate, which could be used in clinically relevant situations, and is the first to report the protection by catechin at this dose under conditions of myocardial ischemia-reperfusion injury.
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