Figure 4.
Glutamate released through system caused glioma Ca2+ oscillations. A, increasing amounts of the cystine were added to three glioma cell lines, thus inducing the release of glutamate in a dose-dependent manner as determined by the highly sensitive enzyme-based bioluminescent assay. B, FURA2-AM–loaded D54-MG cells are shown in a representative field before measuring calcium oscillations at ×40 magnification. C, three representative cells from three coverslips were imaged every 15 s in the presence of cystine or with cystine but in the presence of one of the two system inhibitors, sulfasalazine (SAS) or S-(4)-CPG.