Neurotransmission, synaptic plasticity, and maintenance of membrane excitability require
high mitochondrial activity in neurosecretory cells. Using a fluorescence-based intracellular
O 2 sensing technique, we investigated the respiration of differentiated PC12 cells upon
depolarization with 100 mm K+. Single cell confocal analysis identified a significant
depolarization of the plasma membrane potential and a relatively minor depolarization of the
mitochondrial membrane potential following K+ exposure. We observed a two-phase …