Mapping membrane-potential perturbations of chromaffin cells exposed to electric fields

The numerous and diverse responses of biological systems to electric fields continue to evoke interest in elucidating the fundamental mechanisms of cellular interactions with these fields. In order to. address this issue for excitable cells, responses of bovine adrenal chromaffin cells exposed to dc electric fields in various orientations were investigated. Spatial variations in membrane potential were monitored in single cells as well as in complex clusters of cells using fluorescence video imaging and a voltage-sensitive dye, di-8-ANEPPS. Responses in isolated cells were in general agreement with that predicted by theory. Reversal of the electric field direction did not produce an exactly symmetrical reversal of fluorescent intensities, suggesting structural asymmetries within the cells. Clusters larger than a single cell exhibited more complex responses at the interfaces between cells that were dependent on the orientation of the regions of contact with the electric-field direction. Taken as a whole, the results of this study provide a foundation to understand the interaction of electric fields at the level of tissues and organs.