Figure 2

Poly-APS (0.5 μg/ml) reversible elevated ionic permeability and suppressed neuronal excitability in cultured hippocampal neurones. a) Electrotonic potentials in response to +/- 100 pA current step. Multiple action potential firing was seen in response to +100pA. In the same neurone after 5 minutes application of 0.5 μg/ml poly-APS the electrotonic potential to -100 pA was reduced and action potential activation was depressed. B). Application of poly-APS greatly reduced the input resistance. This reduction was still observed even when membrane potential changes were corrected (n = 6 for control and poly-APS and n = 5 for membrane potential (MP) corrected (** = P < 0.01 student paired t-test). C). Voltage records showing the response to poly-APS and partial recovery of the input resistance after 45 minutes. D) Voltage record showing membrane potential and electrotonic potentials (downward deflections) evoked by -80 pA current pulses and the onset of the response to a brief application of poly-APS (0.5 μg/ml). The development of partial recovery can also be seen. E) Voltage records showing action potential firing evoked by a +50 pA step command and an electrotonic potential evoked by a -50 pA step command. These responses were evoked from a hippocampal neurone that had been exposed to 0.5 μg/ml poly-APS and then placed back in culture for 24 hours.