The small conductance swelling-activated chloride channel in primary rat microglia: Biophysical characterization and its contribution to volume regulation and phagocytosis.

摘要

Microglia are immuno-competent cells of the central nervous system (CNS) that function as macrophages during brain development and pathology. They secrete soluble factors that have neurotoxic and neuroprotective effects. They express ion channels crucial to their function including a swelling-activated chloride channel. Its key biophysical characteristics and some of its physiological functions were investigated. Akin to other swelling-activated conductances, a halide selectivity sequence of I- > Br- > Cl- > F and no time-dependent inactivation at potentials up to 100 mV, even under high extracellular Mg2+, were found. Contrary to the intermediate conductance Iclswell, a small single channel conductance (3 to 5 pS) was found using noise analysis. This suggests that microglial Iclswell is distinct from the Iclswell in other cell types. Drugs that inhibited Iclswell interfered with normosmotic volume regulation and regulatory volume decrease (RVD). Additionally, all Iclswell blockers tested inhibited microglial phagocytosis in a dose-dependent manner.