Fig 15. Effects of culture periods on ZnCl₂-induced inhibition of MTT reducing activity in C6 glioma cells.

Cells were exposed to ZnCl₂ at 0.1 or 1 mM in either the presence or absence of CaCl₂ and EGTA for 1 h, followed by culture for an additional periods from 0.5 to 6 h and subsequent determination of MTT reducing activity. Values are the mean±S.E. of percentages over the maximal activity detected in cells not exposed to any test chemicals in 3 different experiments. *P<0.05, **P<0.01, significantly different from the control value in cells not exposed to ZnCl₂.