Daily membrane capacitance changes in mouse neurons

Capacitance of biological membranes is determined by the properties of the lipid portion of the membrane, as well as morphological features of a cell. In neurons, membrane capacitance is a determining factor of synaptic integration, action potential propagation speed and firing frequency due to its direct effect on the membrane time constant. Besides slow changes associated with increased morphological complexity during postnatal maturation, neuron membrane capacity is largely considered a stable, non-regulated constant magnitude. Here we report that in two excitatory neuronal cell types, pyramidal cells of mouse primary visual cortex and granule cells of the hippocampus, the membrane capacitance significantly changes between the start and the end of a daily light cycle. The changes are large, nearly two-fold in magnitude in pyramidal cells, but are not observed in cortical parvalbumin-expressing inhibitory interneurons. We discuss potential functional implications and plausible mechanisms.