[Pharmacological bases of the vascular impact of Ginkgo biloba extract].

The preferential tissue irrigatory effect of Ginkgo biloba extract in ischaemic areas is largely explained by the direct impact of this product on both arteries and veins. The adrenergic vasoregulatory system and the vascular endothelium are the preferential targets for arterial impact. Ginkgo biloba extract reinforces the physiological vasoregulation of the sympathetic nervous system directly, by acting on neuromediator release, and indirectly, by inhibiting their extraneuronal degradation by catechol-orthomethyltransferase (C.O.M.T.) In the arterial endothelium Ginkgo biloba extract stimulates the release of endogenous relaxing factors, such as endothelium-derived relaxing factor, (EDRF) and prostacyclin. The action of Ginkgo biloba extract on the venous system has been shown to have a venoconstrictor component that maintains the degree of parietal tonus essential to the dynamic clearing of toxic metabolites accumulated during tissue ischaemia. The originality of the vascular impact mechanisms of Ginkgo biloba extract is due to the fact that the product can at the same time combat the phenomena resulting from vascular spasm and with the same efficiency restore circulation in areas subject to vasomotor paralysis.