The present study was carried out to determine the regulation of ginkgolide B(GB)on fast-excitatory postsynaptic potential(fast-EPSP)in the neurons of celiac ganglion(CG)and the mechanisms involved in the GB-induced responses.Intracellular recording was employed to measure the fast-EPSP in the neurons of CG freshly isolated from Guinea Pigs(Cavia porcellus).We found that perfusion of GB(4×10^-6 mol/L)significantly decreased the amplitude of fast-EPSP in the CG neurons(n=12,P<0.05).The fast-EPSP was completely inhibited by a low Ca ²⁺/high Mg ²⁺ Krebs solution(n=3),but significantly enhanced by a high Ca ²⁺ Krebs solution(n=12,P<0.05),suggesting a contribution of extracellular Ca ²⁺ to the generation of the fast-EPSP.The high Ca ²⁺ Krebs solution-induced augmentation of the fast-EPSP was significantly attenuated by GB(n=12,P<0.05).These results indicate that GB negatively regulates fast-EPSP in CG neurons in Guinea pigs through an inhibition on external Ca ²⁺ entry.