Fig. 1.

Inactivation and recovery of Kv2.1 and Kv2.1/Kv9.3 channels. (A) Inactivation of Kv2.1 measured in cell-attached patches from transiently transfected HEK293 cells. Outward currents were elicited by the three-pulse protocol shown in Inset. Briefly, channels were inactivated during a 5-s pulse to various potentials (P2), and the degree of inactivation was determined by the ratio of currents (I₃/I₁) elicited by 80-ms pulses to +40 mV before (P1) and after (P3) the inactivating pulse. Representative traces are shown for P2 of -60 and +20 mV, indicative of closed- and open-state inactivation, respectively. (B) Inactivation of Kv2.1 (○) and Kv2.1/Kv9.3 (•) channels as a function of the potential of the inactivating pulse (n = 6-8). Lines represent least-square fits of the sum of two Boltzmann functions to the inactivation of Kv2.1 (gray line) and Kv2.1/Kv9.3 (black line) channels. (C) Representative traces of inactivation from patches of HEK293 cells transfected with Kv2.1 and Kv9.3 at a cDNA ratio of 1:2. Pulse protocol is identical to A.(D) Recovery from inactivation for Kv2.1 (○) and Kv2.1/Kv9.3 (•) channels was recorded by using a variation of the pulse protocol depicted in A. After maximal inactivation (P2: 10 s at -40 mV), channels were allowed to recover for increasing time intervals at the recovery potential (here -100 mV) before the fraction of channels recovered was evaluated by an 80-ms pulse to +40 mV. Solid lines represent least-square fits of monoexponential functions to the recovery of Kv2.1 (gray line) and Kv2.1/Kv9.3 (black line).