The importance of ion channels for macrophage and microglial activation in vitro.

Microglia, the resident macrophages of the central nervous system (CNS), are activated rapidly in response to neuronal injury. In the search for factors which regulate inflammation resulting from pathology in the CNS, it is logical to focus on changes in the local environment which occur following neuronal death. These include transient alterations in transmembrane ion gradients. Electrophysiological studies have provided information on the range of ion channels expressed by macrophages and microglia in vitro. The purpose of this study was to focus on the biology of macrophages and the role ion channels play in determining their activity. We show that potassium channels are unlikely to be involved in the generation of nitric oxide by activated macrophages and microglial cell lines in vitro. Chloride channels are more likely to contribute to this response. Our results question the functional importance of the observed differences between the potassium channel expression in vitro of macrophages and microglia.