Evaluation of horseradish peroxidase as an intracellular stain in electrophysiological recording

Iontophoresis of horseradish peroxidase into cells during intracellular electrophysiological recording to visualize the neurons recorded from is a powerful technique, but its success depends on a number of critical factors. The described agar injection technique is a simple method for the evaluation of several parameters at once, using procedures which closely resemble recording from, fixing, and processing to visualize the HRP in experimental tissue.