GLUTATHIONE METABOLISM IN PRIMARY ASTROCYTE CULTURES - FLOW CYTOMETRIC EVIDENCE OF HETEROGENEOUS DISTRIBUTION OF GSH CONTENT

The time-course of intracellular glutathione (GSH) values after incuba tion with L-buthionine-(SR)-sulfoximine (BSO), a selective inhibitor o f gamma-glutamylcysteine synthetase, showed that glutathione turns ove r with a half-life of 5 h. Intracellular GSH was assayed by flow cytom etry using three different methods. Astrocytes showed a narrow range o f cellular size but a wide range of intracellular GSH. This heterogene ity was resolved into three distinct subpopulations which represent 20 %, 35% and 45% of the total astrocyte number. The less abundant subpop ulation had the lower GSH content, while the most abundant was the sub population with the higher content. Over 95% of astrocytes were in the G0/G1 phase of the cell cycle, the distribution of cytosolic pH was h omogeneous and the number of viable cells at the time of the assay was 90%. These results show that several pools exist when astrocyte GSH i s considered and these findings may be relevant to the understanding o f brain GSH metabolism.