Comparison of protective effects of catechin applied in vitro and in vivo on ischemia-reperfusion injury in the isolated rat hearts.

AIM To determine overall cardiac effects of flavonoid catechin on ischemia-reperfusion injury in isolated rat hearts in vitro and in vivo. METHODS After perfusing hearts at the pressure of 70 mm Hg, coronary perfusion was interrupted for 30 minutes and then re-established. There were four experimental groups, with 10 rats each. The first group received 100 micromol/L of catechin added to the perfusate 10 minutes before, during, and 10 minutes after ischemia; the second group underwent in vivo pretreatment with catechin (250 mg/kg body weight) applied intragastrically for 10 days; the third group received it as a single dose 1 h before sacrifice; and the fourth group received saline. An additional group of 10 hearts served as untreated, nonischemic time control. The variables included heart rate, atrioventricular conduction time, cardiac rhythm, isovolumetric left ventricular pressure, coronary flow and responsiveness, oxygen consumption, relative cardiac efficiency, lactate dehydrogenase release, and myocardial lipid peroxidation. RESULTS Catechin added to the perfusate increased the coronary flow and ratio of oxygen delivery to myocardial oxygen consumption before ischemia and during reperfusion. Following 30 minutes of reperfusion, isovolumetric left ventricular developed pressure recovered to 42+/-3%, 63+/-3%, 71+/-2%, and 55+/-3% of the initial control values in the control, catechin 1 h, catechin for 10 days, and catechin in vitro group, respectively. Cardiac efficiency and coronary responsiveness were also best preserved in the group receiving catechin for 10 days. CONCLUSION Application of catechin in vitro and in vivo, irrespective of duration of application, resulted in cardioprotection against ischemia-reperfusion injury, but long-term pretreatment provided more favorable effects. Directly applied, catechin acted as a vasodilator.