Oral pretreatment with a green tea polyphenol for cardioprotection against ischemia-reperfusion injury in an isolated rat heart model.

Abstract

Ischemia-reperfusion injury is among the most serious problems in cardiac surgery. Epigallocatechin-3-gallate, a major polyphenolic component of green tea, is thought to be cardioprotective through its antioxidant activities. We investigated cardioprotective effects of oral epigallocatechin-3-gallate pretreatment against ischemia-reperfusion injury in isolated rat hearts and considered possible underlying mechanisms. Rats were given epigallocatechin-3-gallate solution orally at 0.1, 1, or 10 mmol/L (n=12 per group) for 2 weeks; controls (n=12) received tap water alone for 2 weeks. Subsequently, Langendorff-perfused hearts were subjected to global ischemia for 30 minutes, followed by 60 minutes of reperfusion. Recoveries at 60 minutes after reperfusion of left ventricular developed pressure and maximum positive and minimum negative first derivatives of left ventricular pressure were significantly higher in 1-mmol/L group than in 0.1-mmol/L (P<.0001), 10-mmol/L (P<.05), and control (P<.0001) groups. Oxidative stress after reperfusion, as reflected by 8-hydroxy-2'-deoxyguanosine index, was lower in 1-mmol/L group than in control (P<.01) and 0.1-mmol/L (P<.05) groups. Western blot analysis after reperfusion showed p38 activation and active caspase-3 expression to be lower in 1-mmol/L group than in control group (P<.05). Oral pretreatment with epigallocatechin-3-gallate preserved cardiac function after ischemia-reperfusion, an effect that may involve its antioxidative, antiapoptotic properties, although a high dose did not lead to dramatic improvement in cardiac function. Oral epigallocatechin-3-gallate pretreatment may be a novel and simple cardioprotective method for preventing perioperative cardiac dysfunction in cardiac surgery.