Figure 3. Cellular response to veratridine-induced Na⁺ influx.

A, results of Na⁺ imaging obtained from a group of neurones before (Cont), and after a 1 h exposure to 50 μM veratridine. B, results of Ca²⁺ imaging before (Cont), and after a 1 h exposure to 50 μM veratridine. C, simultaneous increase in [Na⁺]_i and [Ca²⁺]_i in representative neurones after veratridine exposure. Cells were preincubated with Sodium Green and Calcium Orange. Top row, phase-contrast images. Middle row, Na⁺ fluorescence images of the same neurone. Bottom row, Ca²⁺ fluorescence images of the same neurone. Note the increase in green and red fluorescence indicating a simultaneous rise in [Na⁺]_i and [Ca²⁺]_i.