Figure 4. Phalloidin prevents the inhibition by cytochalasin D of the stimulatory insulin effect on K⁺ currents.

A, current traces (same voltages as in Fig. 1) from cells in the absence of insulin (left), 6 h after exposure to 10 nM insulin in the presence of 1 μM cytochalasin D (centre), and with insulin + cytochalasin D after a 4 h pre-incubation with 2.5 μM phalloidin (right). Note that cytochalasin D prevents insulin from augmenting the peak outward and steady-state currents (centre), but not if phalloidin is present (right). Cell capacitances are 51.6 (left), 57.4 (centre) and 48.8 pF (right). B, summary histogram showing current densities for I_t (left) and I_ss (right) in control myocytes (n= 34), in untreated STZ-diabetic myocytes (n= 30), and in diabetic myocytes treated with 10 nM insulin (n= 16), with insulin + cytochalasin D (n= 18), and with the combination of insulin, cytochalasin D and phalloidin (n= 22).