FIGURE 5.

The effect of Cd²⁺ on the light-scattering change and on the mechanical signal in response to a train of electrical stimuli. (A) The light-scattering change (−ΔI) recorded from secretory terminals of a mouse neurohypophysis in response to seven stimuli delivered at 15 Hz in normal mouse Ringer's solution (Control, blue trace) and after 15 min in a Ringer's solution containing 1 mM CdCl₂ (black trace). (B) The mechanical response (ΔZ), recorded from a different preparation, to an identical train of stimuli. Red trace, Control Ringer's solution; black trace, 15 min in a Ringer's solution containing 1 mM CdCl₂. Note that both the S-wave of the light-scattering change and the summated dips (slope change) of the train of mechanical spikes are eliminated when Ca²⁺-entry into the terminals is blocked by Cd²⁺. All traces were low-pass filtered at 1 kHz.