Abstract: AIM: To study the effects of shensongyangxin capsule, a traditional Chinese medicine, on c-type Kv1.4 channels in xenopus laevis oocytes by two-electrode voltage-clamp technique. METHODS: Defolliculated oocytes (stages V VI) were injected with transcribed cRNAs of ferret Kv1.4△N channels. During recording, oocytes were continuously perfused with control solution or shensongyangxin. RESULTS: Shensongyangxin decreased the currents during voltage steps in a voltage-dependent manner. The block increased with positive potentials and the voltage dependence of block matched the sum of monoexponentials and linear relationships. Shensongyangxin accelerated the inactivation of current during the voltage step and prolonged the time of recovery from the inactivation. CONCLUSION: These results suggest that shensongyangxin blocks the Kv1.4△N channel, which may underly its antiarrhythmic mechanisms.