Xenbase Image ID: 121746

Figure 10. Paired pulse recovery protocols reveal a slow recovery from inactivation despite nearly complete recovery from block in the peak tail current. Recovery from inactivation was assessed using the indicated voltage-protocol. The duration of the initial inactivating step to +160 mV was 40 ms. Recovery steps were varied from 50 μs to 40 ms, although not all are displayed. In A and B, currents were activated with 10 μM Ca2+, and the recovery potential was either −80 mV (A) or −120 mV (B). In C and D, selected traces from A and B are shown on a faster time base. For faster time records, traces correspond to recovery intervals of 0, 0.05, 0.25, 0.5, 1.0, 2.0, and 5.0 ms. Triangles draw attention to the amount of outward current present immediately after completion of the capacitative transient associated with the second test step to +160 mV. For brief recovery intervals, this instantaneous level of current is identical to the steady-state level of current at +160 mV. With longer recovery intervals, the amplitude of the instantaneous current indicated by the triangles increases even as the tail current at −80 or −120 mV is beginning to decrease. The dotted line indicates the zero current level. In C, the percent recovery measured from the paired pulse protocol is plotted as a function of the recovery duration at each of three recovery potentials with 10 μM Ca2+. The solid lines represent single exponential fits to the recovery time course. At −80 mV, a two exponential fit gave a somewhat better description of the recovery time course, but, at more negative potentials, a two exponential time course did not substantially improve the quality of the fit. At −160 mV, τr = 0.5 ms; at −120 mV, τr = 0.61 ms; and at −80 mV, τr = 0.67 ms. In D, the time course of recovery in the paired pulse protocol is shown for 300 μM from the traces in Fig. 11 B. At −160 mV, τr = 0.84 ms; at −120 mV, τr = 1.00 ms; and at −80 mV, τr = 1.04 ms. Image published in: Lingle CJ et al. (2001) © 2001 The Rockefeller University Press. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View

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