Culture environment and channel-mediated potassium fluxes in astrocytes

Barium-sensitive channel-mediated unidirectional K+ influx into mouse and rat astrocytes and its dependency upon cell density and serum was investigated. The huge difference in flux velocity between mouse (about 1000-2000 nmol X mg-1 X min-1, depending on culture conditions) and rat astrocytes (100-20 nmol X mg-1 X min-1) could not be primarily explained by an effect of culture conditions. Some small effects of both cell density and the use of fetal calf serum were, however, seen on the fluxes in mouse as well as rat astrocytes. It seems that rat astrocytes in culture lose irreversibly a glial K+ channel. An alternative is that the results may reflect a lower level of K+ channels in rat astrocytes in situ.