Fig. 5. Whole cell voltage-dependent currents in muscle fibres from honeybee. (A) In voltage-clamp mode, in the presence of Tyrode's solution (2 mmol l^–1 Ca²⁺) as the extracellular solution, a series of depolarizations bringing the membrane potential from –80 mV to –30, –10, +10 and +30 mV over a period of 200 ms activated both inward and outward currents. (B) In a fibre depolarized to +10 mV for 100 ms, tetrodotoxin (TTX) had no obvious blocking effect on the inward current (middle trace). However, Cd²⁺ and La³⁺ completely blocked the inward component of the voltage-activated currents (lower trace).