Martentoxin,a 37 residues peptide purified from the venom of Chinese scorpion Buthus martensi Karch (BmK),was capable of blocking large-conductance Ca2+-activated K+ (BK) channels in adrenal medulla chromaffin cells with a great preference.In the present study,the pharmacological effect of martentoxin on the specific BK channels composed of α and β1 subunits was investigated on HEK293T by electrophysiological approach.The results showed that martentoxin could potently increase the activities of the specific BK channels composed of α and β1 subunits in the presence of cytosolic Ca2+,while no effect on the specific BK channels composed of α and β1 subunits in the absence of cytosolic Ca2+.The enhancive effect of martentoxin was dose-dependence,but without voltage dependence.