Fig. 1.

400 µM Cd²⁺ application to magnocellular neurosecretory cells inhibited most of the afterhyperpolarization (AHP) in current clamp. AHPs were evoked using a pulse train of 20 spikes and measured at peak (medium and slow AHP, mAHP + sAHP) and 1 s (sAHP) following the pulse. A: example of an oxytocin (OT) neuron before and after Cd²⁺ application of an AHP in current clamp. The only remaining portion of the AHP is small (B and C). Summary data for Cd²⁺ inhibition at the peak current and 1 s following the pulse train in both OT (n = 6) (B) and vasopressin (VP) (n = 6) (C) neurons are shown. Cd²⁺ significantly inhibits AHPs in OT neurons at peak (***P < 0.001) and 1,000 ms (**P < 0.01). Cd²⁺ significantly inhibits AHPs in VP neurons at peak (***P < 0.001) and 1,000 ms (*P < 0.05). All data were evaluated with a 2-way repeated-measure ANOVA.