Antagonistic Effects of Gingko biloba and Sophora japonica on Cerebral Vasoconstriction in Response to Histamine, 5-Hydroxytryptamine, U46619 and Bradykinin.

The aim of this study was to evaluate, for the first time, the antagonistic effects of Gingko biloba leaf (GB) and Sophora japonica L. flower bud (SJ) extracts on cerebral vasoconstriction in response to KCl, extracellular Ca, histamine, 5-hydroxytryptamine (5-HT), 9,11-dideoxy-9,11-methanoepoxy prostaglandin (PG) F(U46619) and bradykinin (BK), in order to explain their traditional application for diseases associated with cerebral vasospasm. Isolated porcine basilar arteries (PBA) and endothelial cells from them were used as the study materials. Neither SJ nor GB had any effect on the contractions induced by KCl and extracellular Ca. SJ significantly inhibited the contraction induced by histamine, 5-HT, U46619 and BK, whereas GB inhibited histamine-induced contraction, but had no effects on the contractions induced by 5-HT, U46619 and BK. In the presence of diphenhydramine (a H₁ receptor antagonist), ketanserin (a 5-HT₂ receptor antagonist) and ONO-3708 (a thromboxane (TX) A₂/PG receptor antagonist), the inhibitory effects of these extracts on the contractions induced by histamine, 5-HT and U46619 were abolished. SJ significantly inhibited the contractions induced by BK and PGF, but in the presence of ONO-3708 (10 M) had no effect on them. BK enhanced the production of PGF from cultured PBA endothelium cells, and SJ significantly attenuated this enhancement. These results suggest that SJ and GB have a H₁-antagonistic effect, and that SJ also attenuates cerebral vasoconstriction mediated via 5-HT₂ and TXA₂/PG receptors. These findings appear to explain why SJ has been used traditionally as a therapeutic medication for cerebral vasospasm after cerebral hemorrhage. [ABSTRACT FROM AUTHOR]