Fig. 2.

Ca²⁺ responses in chromaffin cells exposed to a single 5 ns, 17 MV/m pulse in the absence of extracellular Ca²⁺. (A) Averaged responses ± s.e. (n = 3) of cells that did not respond to the pulse. (B) Averaged cell responses ± s.e. (n = 24) of cells exhibiting single Ca²⁺ transients. The arrow indicates when the pulse was delivered to the cells. Here and in all subsequent figures, F/F₀ was calculated as described in Methods. Error bars not shown are within the thickness of the line. Fluorescence photomicrographs of chromaffin cells exposed to a single 5 ns pulse showing (C) global versus (D) more localized Ca²⁺ responses before and after pulse application. The red circles represent the areas with increased fluorescence.