Abstract

The effect of ethanolic Ginkgo biloba L. leaf extract (GE) on vascular smooth muscle contractility and endothelium-dependent relaxation were investigated in this study. Direct applications on isolated vessels from Wistar rats as well as animal feeding with the extract (dosage of 0.32 ml/kg for 10 days) were used. Vascular contractility of small isolated mesenteric arteries of the animals was examined using wire myography. The extract significantly suppressed the vascular contraction to KCl in dose-dependent mode (4 ´ 10^-3mg/ml of phenolic compounds (PC) – up to 82%; 4 ´ 10^-2 mg/ml of PC – 37%, p < 0.01; and 0.4 mg/ml of PC – 4%, p < 0.001). Ten (10) days of administration of the extract for the animals in drinking water resulted in slight decrease of contractility to KCl (95%) and phenylephrine (88%). Both the endothelium-dependent relaxation to acetylcholine and endothelium-independent relaxation to sodium nitroprusside (SNP) were slightly improved by shifting the dose–response curve leftward with the significantly improved maximum relaxation (86.39 ± 3.61 to 60.84 ± 12.45%, p < 0.05 with 1 mM acetylcholine and 82.86 ± 8 to 55.86 ± 10.85%; p < 0.05, with 1 mM SNP). These results suggested that GE improved and revealed the vasorelaxant effects mainly attributed to smooth muscle involving mechanisms without impairment of the endothelium-depended relaxation.

Key words: Ginkgo biloba, myography, contractility, endothelium, vascular smooth muscles.