ATP-induced changes in [Ca
]i in C6 glioma. (A) Representative response for ATP (100 μM) showing rapid and slow components of decay. (B) Typical ATP response in Ca2+-free PSS. (C) ATP response following gadolinium (Gd3+) pretreatment (1 μM, for 3 min). (D) ATP response in the presence of SKF96365 (25 μM, pretreatment for 3 min). (E) Quantification of durations of ATP responses for the different treatments (measured at one-half of peak response; N = 4/treatment). Values are mean ± SEM. *p < 0.001 compared with control.