Fig. 6.

Tyrphostin 23 has no significant effect on Ca²⁺ currents. Whole-cell currents are shown from a cell stimulated before and after treatment with 100 μmtyrphostin 23. Only data from the first three depolarizations of a train are shown. Currents before treatment (left) are approximately equal to those after treatment with tyrphostin 23 (right). The extracellular [Ca²⁺] was 2 mm. Although K⁺ currents were blocked by intracellular Cs⁺, no Na⁺ channel inhibitors were used. The early spike in the current trace is carried by Na⁺. Neither the magnitude of the Ca²⁺ currents nor the rate of inactivation is affected by tyrosine kinase inhibition.