Imbalance of Ca2+ and K+ fluxes in C6 glioma cells after PDT measured with scanning ion-selective electrode technique

Photodynamic therapy (PDT) possesses the capacity to lead to death of C6 glioma in vitro and in vivo. The purpose of this study was to investigate whether Ca²⁺ and K⁺ homeostasis of C6 glioma cells were affected by PDT. C6 glioma cells were randomly divided into five groups: control group, Hematoporphyrin derivative (HpD) group (10 mg/l, without irradiation), PDT group (HpD 10 mg/l + irradiation), PDT&6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX) group (HpD 10 mg/l + CNQX 50 mol/l + irradiation), and HpD&CNQX group (HpD 10 mg/l + CNQX 50 mol/l, without irradiation). Glioma cells in PDT and PDT&CNQX group were subjected to PDT. Cells in PDT&CNQX group were administered α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist CNQX prior to PDT on C6 glioma cells. The changes of Ca²⁺ and K⁺ fluxes were studied by using a non-invasive scanning ion-selective electrode technique (SIET). Morphology of C6 cells was observed with optical microscopy. PDT induced Ca²⁺ influx and K⁺ efflux significantly, which resulted in death of C6 cells. When AMPA glutamate receptor antagonist CNQX was applied, Ca²⁺ influx and K⁺ efflux were partly blocked up and viability of C6 cells increased. These results indicate that Ca²⁺ influx and K⁺ efflux may correlate with the treatment effects of PDT on C6 glioma cells.