Astrocyte proliferation in culture following exposure to potassium ion

Following brain injury astrocytes swell acutely and proliferate thereafter. To investigate the direct relationship between swelling and proliferation, cultured astroglial cells were exposed to 60 mM K+ ion or hypo-osmolar (205 mOsm) electrolyte solution for 1 h to cause transient swelling. Proliferation was assessed by bromodeoxyuridine (BrdU) uptake 24 and 96 h later. The cells were double-labelled with antibodies to glial fibrillary acidic protein (GFAP) and BrdU. At 96 h the GFAP immunoreactive cells exposed to K+ exhibited 44.9% uptake versus 27.0% and 21.1% for control and hypo-osmolar exposed cells, respectively. We conclude that swelling of astroglia in vitro does not induce cell proliferation but transient depolarization following exposure to high K+ does.