Tetrandrine effects on calcium currents in cultured neurones of foetal mice.

Tetrandrine, a bis-benzyl-isoquinoline alkaloid from the roots of Stefania Tetranda blocks calcium currents in cultured neurones of the spinal cord of foetal mice. The concentration of half-maximal effect (Kd) measured 100 ms after the beginning of a depolarizing pulse (-80 mV-0 mV) is 8 microM. While high- and low-voltage activated (HVA, LVA) currents are both blocked by Tetrandrine, the slowly inactivating HVA currents appear to be a primary target.