Fig. 2. Burst of action potentials and associated contractions in the myoepithelium sheet. (A) Series of spontaneous action potentials from subumbrellar myoepithelium evoked by a single stimulus, showing a successive increase in both the amplitude and duration. The dotted line indicates 0 mV. (B) Trace of strain gauge output, showing that the force of contractions of the myoepithelium sheet became stronger as both amplitude and duration of the action potentials increased. The external solution was ASW.