Ginkgo biloba extract EGb 761 attenuates myocardial stunning in the pig heart

Myocardial stunning, a transient contractile dysfunction that appears following a brief period of ischemia, is at least partly due to the production of oxygen-derived free radicals. The objective of the present study was to determine whether the Ginkgo biloba extract EGb761, which has antioxidant properties in vitro, can attenuate myocardial stunning in vivo. Forty-seven anesthetized open-chest farm pigs underwent 10 min of occlusion of the left anterior descending coronary artery (LAD), followed by 3 hours of reperfusion. They were pretreated with either physiological saline, 100 mg or 300 mg,of EGb 761 (Protocol I) or 3 mg or 9 mg of ginkgolide B (GkB) (Protocol 11). Contractile function was assessed by sonomicrometry. Both doses of EGb 761 significantly improved recovery of contractile function in the reperfused myocardium with segment shortening averaging 23 +/- 5% of baseline values at 3 hours post-reflow in controls versus 81 +/- 10% and 57 +/- 12% in the EGb100 and EGb300 groups, respectively (p < 0.05 vs control in both cases). In contrast, neither dose of GkB improved functional recovery during reperfusion. ESR experiments revealed that EGb761 resulted in a 59% decrease in myocardial spin-adduct release during reperfusion (p < 0.05 versus control and GkB groups). A significant 28% decrease (p < 0.05 vs control group) was also obtained in GkB-treated animals. These results indicate that EGb 761 can attenuate myocardial stunning following a brief ischemic insult in the in situ pig heart by an effect that involves a decrease in the formation of free radicals. As the effect of EGb 761 on functional recovery cannot be explained by the presence of GkB, the beneficial action of the extract on myocardial stunning likely involves complementary effects of both its non-ginkgolide and ginkgolide constituents.