KV7/KCNQ Channels Are Functionally Expressed in Oligodendrocyte Progenitor Cells
Figure 5
KV7/KCNQ channel current (IK(Q)) in OPCs of rat primary cultures.
(A) IK(Q) was measured with whole cell patch clamp recording from OPCs. Left insert: Standard IM deactivation voltage protocol used to measure IK(Q). Hyperpolarizing voltage steps were given from a holding potential of −20 to −60 mV (in 10 mV decrements). Currents recorded are shown below; the dashed line represents the zero current level. Right: Current recorded in response to the voltage step to −40 mV. IK(Q) was measured as the inward relaxation current caused by deactivation of IK(Q) during the voltage step; i.e., the difference between the instantaneous current at the beginning and the steady-state current at the end of the voltage step (arrows). (B) Current–voltage relationship for IK(Q) (mean data from 17 OPCs) showing that IK(Q) amplitude was voltage dependent and was largest at −40 mV. (C) IK(Q) deactivation time constants were directly related to voltage (mean data from 17 OPCs). Correlation coefficient r = 0.93.