Figure 6. Inward currents elicited by hyperpolarizations.

Command potentials for A and B are shown in the uppermost trace. From a holding potential of −100 mV, 60 s hyperpolarizing pulses were applied in 10 mV increments from −110 to −160 mV. A, currents in the presence of 0.3 mm[K⁺]_o; B, currents in the presence of 0.1 mm[K⁺]_o. Steady-state currents were primarily determined by I_K1. Both inward and outward I_K1 were much larger in the presence of 0.3 mm[K⁺]_o. C, expanded sweep of the inward current labelled a in panel B demonstrating the irregular time course of the inward current.