Effects of extract of Ginkgo biloba on spasms of the basilar artery and cerebral microcirculatory perfusion in rats with subarachnoid hemorrhage.

This study was aimed at investigating the effects of extract of Ginkgo biloba (EGb) on cerebral vasospasm and microcirculatory perfusion after subarachnoid hemorrhage (SAH). An endovascular piercing method was used to induce Wistar rat SAH models, and animals were divided into sham-operated, vehicle controls, and EGb-treated groups. EGb was injected intraperitoneally 30 minutes before operation and was repeated every 6 hours, with a single dose of 15 mg/kg bw. Diameters of basilar arteries before and after operation were measured. Microcirculatory blood perfusion of parietal lobe cortex was detected using a laser Doppler flow-meter probe within 24 hours. Endothelin-1 levels in both plasma and brain tissue were detected at different time points. The results showed that SAH caused an immediate drop in microcirculatory blood flow in vehicle controls, which persisted for 24 hours. Endothelin-1 levels in both plasma and brain tissue increased after SAH. EGb partly reversed spasms of the basilar artery and antagonized a drop in microcirculatory blood flow. EGb also prevented an increase in endothelin-1 both in plasma and in brain tissue. In conclusion, EGb, by antagonizing the overproduction of endo- thelin-1, partly reverses cerebral vasospasm and improves microcirculation, and thus relieves secondary ischemic brain injury after experimental SAH.