EFFECTS OF 7-BROMOETHOXYBENZENE-TETRAHYDROPALMATINE ON VOLTAGE-DEPENDENT CURRENTS IN GUINEA-PIG VENTRICULAR MYOCYTES

AIM: To study the anti-arrhythmic mechanism of 7-bromoethoxybenzene-te trahydropalmatine ( EBP). METHODS: Whole-cell current and voltage clam p on isolated guinea pig ventricular cells. RESULTS: EBP 30 mu mol . L (-1) prolonged APD(90) from 430 +/- 47 ms to 514 +/- 61 ms (n = 5, P < 0.05) without effects on the action potential amplitude and resting p otential. Delayed outward K+ current and its tail current were blocked by EBP in a concentration-dependent fashion, while EBP did not change the amplitudes of the sodium current, the L type calcium current, and the inwardly rectifying potassium current. CONCLUSION: The mechanism of anti-arrhythmic action of EBP was to prolong the APD through inhibi ting the delayed rectified potassium current.