IDENTIFICATION OF THE VOLUME-SENSITIVE ORGANIC OSMOLYTE ANION CHANNELIN HUMAN GLIAL-CELLS

Cellular use of small organic solutes known as organic osmolytes for r egulation of the volume of the cell is a universal biological phenomen on. During swelling, cells open an anion channel which allows for effl ux of these solutes. This channel is known as the volume-sensitive org anic osmolyte/anion channel (VSOAC). Anion channels with properties id entical to VSOAC were found in human brain cells obtained following pe diatric neurosurgical procedures, The tissues examined included tumors as well as putatively normal gray and white matter astrocytes, The ce lls activated an anion conductance when swollen by hypotonic shock. Ba seline currents in these cells were generally small and increased up t o 30-fold within 10 min following the onset of swelling. The anion cha nnel activated by swelling was outwardly rectified and inactivated by depolarization, both characteristic of the VSOAC, These observations i ndicate that human glial cells and tumor cells activate VSOAC followin g cellular swelling. This suggests that organic osmolyte efflux can be modulated during brain swelling by pharmaceuticals which modulate VSO AC.