Fig. 1. Effects of dexmedetomidine on hypothalamic paraventricular nucleus magnocellular neurons in current clamp.  A and  B are the responses to 30 and 1,000 nm dexmedetomidine, respectively.  Ab and  Bb are the instantaneous spike rates of the neurons in  Aa and  Ba , respectively. Dexmedetomidine elicited decreases in the firing-action potential accompanied by a decrease in the input resistance (as indicated by responses to hyperpolarizing test pulses of −50 pA, 300 ms duration, administered every 20 s).  (C ) The dose–response curve of dexmedetomidine-induced hyperpolarization. The number of neurons tested for each dose is eight.