Published online Oct 1, 2004. doi: 10.3748/wjg.v10.i19.2842
Revised: February 11, 2004
Accepted: February 18, 2004
Published online: October 1, 2004
AIM: To examine the effects of berberine, an isoquinoline alkaloid with a long history used as a tonic remedy for liver and heart, on ion channels of isolated rat hepatocytes.
METHODS: Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of berberine on the delayed outward potassium currents (IK), inward rectifier potassium currents (IK1) and Ca2+ release-activated Ca2+ currents (ICRAC) in enzymatically isolated rat hepatocytes.
RESULTS: Berberine 1-300 μmol/L reduced IK in a concentration-dependent manner with EC50 of 38.86 ± 5.37 μmol/L and nH of 0.82 ± 0.05 (n = 8). When the bath solution was changed to tetraethylammonium (TEA) 8 mmol/L, IK was inhibited. Berberine 30 μmol/L reduced IK at all examined membrane potentials, especially at potentials positive to +60 mV (n = 8, P < 0.05 or P < 0.01 vs control). Berberine had mild inhibitory effects on IK1 in rat hepatocytes. Berberine 1-300 μmol/L also inhibited ICRAC in a concentration-dependent fashion. The fitting parameters were EC50 = 47.20 ± 10.86 μmol/L, nH = 0.71 ± 0.09 (n = 8). The peak value of ICRAC in the I-V relationship was decreased by berberine 30 μmol/L at potential negative to -80 mV (n = 8, P < 0.05 vs control). But the reverse potential of ICRAC occurred at voltage 0 mV in all cells.
CONCLUSION: Berberine has inhibitory effects on potassium and calcium currents in isolated rat hepatocytes, which may be involved in hepatoprotection.