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. 2005 May 12;565(Pt 3):751–756. doi: 10.1113/jphysiol.2005.087312

Figure 3. Effects of KChIP2a and DPPX on Kv4.3 currents expressed in CHO cells.

Figure 3

A–D, current tracings (initial 300 ms) elicited by test steps (1000 ms) from −80 mV to −40, −20, 0, +20, +40 and +60 mV in CHO cells stably transfected with Kv4.3 (A), Kv4.3 plus KChIP2a (B, □), Kv4.3 plus DPPX (C, ○), and Kv4.3 plus KChIP2a plus DPPX (D, ▪). E, current–voltage relations of Ito in the transfected CHO cells. F, voltage dependence of fast time constant of Ito inactivation determined from fitting single exponential curves to individual current traces. G, normalized steady-state inactivation (I/I0) curves for Ito. Fitting of a Boltzmann function to mean data yielded the following potentials of half maximum inactivation (V0.5, dotted lines): −31.5 mV for Kv4.3 plus KChIP2a, −57.0 mV for Kv4.3 plus DPPX, and −39.2 mV for Kv4.3 plus KChIP2a plus DPPX, with slope factors (k) of −9.2, −7.8 and −8.9 mV, respectively. H, time course of recovery from inactivation of Ito, test pulse +50 mV, recovery potential −80 mV. Curve fitting yielded τ-values of 33 ms, 46 ms and 17 ms, respectively.