Figure 6. Clonidine alters the voltage response to hyperpolarizing current pulses.

A, responses in a representative neuron to hyperpolarizing current steps. Cells were held at −70 mV using DC injection and the amplitude of the current pulses adjusted for each condition to yield peak voltage deflections of −10, −20 and −30 mV. Clonidine (10 μm, grey traces) reduced the amplitude of the voltage sag as well as the depolarizing overshoot at the end of the current pulse. B, summary of the voltage sag ratio (see text for definition) under control conditions and in the presence of clonidine (n= 7). C, summary of the voltage overshoot ratio (see text for definition) under control conditions and in the presence of clonidine (n= 7). *P < 0.05. The data presented in B and C are from −10 mV peak amplitude hyperpolarizations for each cell.