Effects of barbiturates on energy metabolism by cultured astrocytes and neurons in the presence of normal and elevated concentrations of potassium.

Rates of consumption of oxygen and of the formation of CO2 from [U-14C]glucose were studied in primary cultures of either astrocytes or neurons of the cerebral cortex. An increase of the extracellular concentration of potassium from 5 to 55 mM caused an increase in uptake of oxygen and in the production of CO2 in the astrocytes but not in the neurons. Pentobarbital (0.25-1.0 mM) or phenobarbital (1 mM) abolished the stimulation of oxygen uptake and/or the production of CO2 produced by potassium in the astrocytes with less (CO2 production) or no (oxygen uptake) effect at a normal concentration of potassium. In the neurons, pentobarbital (0.1-1.0 mM) caused, in contrast, a moderate inhibition of the production of CO2 and uptake of oxygen which was at least as pronounced at the small concentration of potassium. These results suggest that the pronounced inhibition of the stimulation of uptake of oxygen induced by potassium in brain slices is exerted on astrocytes, whereas the more modest decrease in uptake of oxygen at a small concentration of potassium is a neuronal phenomenon.