USE OF CR-51 CELL LABELING TO DISTINGUISH BETWEEN RELEASE OF RADIOLABELED AMINO-ACIDS FROM PRIMARY ASTROCYTE CULTURES BEING DUE TO EFFLUX OR CELL-DAMAGE

Continuous perfusion methods are widely used to monitor release of sub stances, particularly transmitters, from brain cell cultures growing a s monolayers. However, if stimuli used to produce release also cause l oss or lysis of cells, the appearance of label in the perfusate due to such effects will be indistinguishable from release. Using a perfusio n method we have studied release of preloaded, radiolabelled amino aci ds from primary astrocyte cultures due to a variety of stimuli; hypoto nic or high K+ media, activation of beta-receptors or swelling-induced release due to isosmotic ethanol. In this study primary astrocyte cul tures were simultaneously labelled with (Na2CrO4)-Cr-51 and allowed to take up radiolabelled D-aspartate or taurine. It was found that while all of the above methods caused release of radiolabelled amino acids none caused release of Cr-51 into the perfusion fluid. In contrast, pe rfusion with 0.05% (v/v) Triton X-100 did lead to release of Cr-51. Th us a variety of means of inducing swelling or shape changes in astrocy tes causes true release of radiolabelled amino acids and simultaneousl y monitoring Cr-51 release seems a convenient means of distinguishing such release from cell loss or lysis.