Loss of an activity-dependent hyperpolarization in the DCMD axon following AMPK pathway activation.

<p>(<b>A</b>). The DCMD axon hyperpolarizes during periods of high frequency activity in response to visual stimulation. The shift in membrane potential occurs with no change in the reversal of the afterpotential (side panel), suggesting that this is an electrogenic effect. Black and grey traces in right-side panel are from time points in raw trace indicated by black and grey asterisks, respectively. (<b>B</b>). The membrane potential shows similar hyperpolarizing shifts following electrical stimulation of the axon that generates APs. (<b>C</b>). Electrically stimulated activity fails to evoke a hyperpolarization during ouabain treatment (10⁻⁴ M). (<b>D</b>). There is no change in input resistance before the activity-dependent hyperpolarization (pre) compared to during the event (post). (<b>E</b>). This hyperpolarization is greatly reduced after ouabain application (10⁻⁴ M; P<0.05). (<b>F</b>). Metformin (10 mM) significantly reduces the hyperpolarization in response to 100 Hz electrical stimulation (P<0.05).