Effects of an extract of Ginkgo biloba on rabbit isolated aorta

1. Extract of Ginkgo biloba (Gb) provoked a dose-dependent contraction of spirally-cut rabbit aortic strips (EC50 congruent to 1.0 mg/ml) by an action that was antagonized by phentolamine (10(-7) M). 2. Inhibitors of catecholamine re-uptake, cocaine (10(-5) M) and desipramine (10(-7) M) potentiated the contractile effect of norepinephrine (NE), but inhibited the contractile effects of Gb and tyramine. 3. A comparison of the actions of Gb, NE and tyramine using aortic strips prepared from control and reserpine-treated rabbits revealed that reserpine treatment increased the response to NE but decreased the response to Gb and tyramine. 4. The contractile action of Gb on rabbit isolated aorta involves, at least in part, a release of catecholamines from endogenous tissue stores.