Figure 1. Blockade of the apamin-sensitive afterhyperpolarization (mAHP) in CA1 neurones increases excitability.
A, IAHPs were evoked in the whole-cell configuration by a 200 ms depolarizing pulse to –20 mV followed by a return to the –55 mV holding potential. IAHPs were obtained in the presence and absence of apamin (100 nm). After application of apamin, the medium-duration component (ImAHP) of the tail current was selectively inhibited. Broken line indicates zero current. B, apamin increased the number of action potentials. Ba, response of a pyramidal neurone to a 1 s depolarizing current pulse. Bb, response of the same neurone to the same depolarizing current pulse in the presence of apamin (control cells fired a mean ± s.e.m. of 4.7 ± 1.2 action potentials/depolarizing pulse, which increased to 6.7 ± 1.7 with apamin; n = 5; P = 0.04; paired Student's t test). From Stackman et al. 2002, with permission.