Abstract
The electrical properties of neuronal cells rely on gradients of ions across their membranes and the extracellular fluid (ECF) in which they are bathed. Little is known regarding how the ECF volume and content is maintained. In this issue, Li et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201907138) identify the kinase SIK3 in glia as a key signal transduction regulator in ion and volume homeostasis in Drosophila peripheral nerves.