Effects of EGTA on ZnCl₂-induced inhibition of MTT reducing activity in C6 glioma cells.

<p>(A) Cells were exposed to ZnCl_<b>2</b> at concentrations of 0.15 to 1 mM in either the presence or absence of CaCl_<b>2</b> and EGTA for 1 h, followed by culture for an additional 24 h and subsequent determination of MTT reducing activity. (B) Cells were also exposed to ZnCl_<b>2</b> at 0.1 or 1 mM in either the presence or absence of CaCl_<b>2</b> and EGTA for different periods from 10 to 60 min, followed by culture for an additional 24 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 ZnCl_<b>2</b>.