Single cell assay of exocytosis from adrenal chromaffin cells using "perforated patch recording".

We have combined "perforated patch recording" with phase detection to examine depolarization-induced changes in membrane capacitance (delta Cm) in bovine adrenal chromaffin cells. With this technique, voltage dependent Ca2+ currents and resultant delta Cm's often show little rundown over 1-2 hours even when the free Ca2+ concentration of the pipette is in the millimolar range. By limiting washout of cytosolic components and by maintaining more intact cytosolic Ca2+ buffering, this approach should facilitate the study of stimulus-exocytosis coupling evoked by physiological stimuli which involve cell metabolism and/or membrane receptor triggered second messenger cascades.