The Effects Of EGb On Bioelectric Activity Of Neurons Of Inferior Mesenteric Ganglion And On Mechanic Activity Of Smooth Muscle Cells Of Distal Colon Of Guinea Pig

1.The bioelectrical effect of EGb761 on the neurons of the guinea-pig inferior mesenteric ganglia in vitroObjective: To investigate the bioelectrical effects of ginkgo biloba extract (EGb) on neurons of sympathic ganglions and further reveal the mechanism of EGb to regulate colon functions innervated by inferior mesenteric ganglion (IMG). Methods: Intracellular recordings were performed from neurons of the isolated guinea pig IMG. Results: Superfusion of the IMG with EGb761 (35 mg~350mg/L) induced a dose-dependent membrane depolarization in the majority (71.0%) neurons; 19.4% cells were evoked a hyperpolarization and 9.7% neurons a biphasic response with an initial depolarization and followed hyperpolarization. The EGb761 depolarization was associatied with a variety of input membrane resistance (Rm) changes including marked decrease , increase and no apparent change. The EGb761 depolarization was partially changed in a low Ca2+ (0.25mmol/L) / high Mg2+ (12.0mmol/L) Krebs solution, but not changed appreciably by cholingeric-receptor and adrenergic-receptor antigonists. EGb761 also attenuated the depolarization induced by exogenously applied 5-HT or BOM. Conclusion: EGb761 can produce a electrophysiological action on IMG neurons by non-cholinergic and non-adrenergic way and the mechanism may be a regulation action associated with influence on the release of other neurotransmitters.2. Effect of EGb761 on colonic smooth muscle cells in guinea pigObjective: To investigate the effect of Extract of Ginkgo biloba (EGb) on relaxation ofcolonic smooth muscle cells of guinea pig. Methods: Smooth muscle cells wereisolated from the colon of the guinea pig. Relaxation in response to EGb761 ,measured by micrometry, was observed. Results: Isolated smooth muscle cells were obstaind. When incubated with 0.11, 0.22, 0.44, 0.88, 1.75 and 3.5 g/L of EGb761 , the most relaxatant response of smooth muscle cells that is in 1.75 g/L is 12.79% (P<0.05) . EGb761 (1.75 g/L) significantly inhibited 44.13% of contraction response of colonic smooth muscle cells caused by Ach (P<0.01). Forskolin increased relaxatant effect of EGb761 on colonic smooth muscle cells in guinea pig to 8.87% compared with effect of only EGb761. Conclusion: EGb761 has a direct relaxatant effect on the colonic smooth muscle cells of guinea pig, and this effect of EGb761 may mediated partly by cAMP messenger pathway.