Tissue swelling and taurine efflux from the hippocampus during oxidative stress. Hippocampal slices were perfused with aCSF containing 2 mM H2O2 from t = 0 min to the end of the data sampling period shown. Values are the mean ± SEM for 3-12 independent measurements. (A) The intrinsic optical signal (IOS) was calculated for areas of the stratum radiatum in the CA1 region of the hippocampus. Slices incubated with normal aCSF during preparation (solid symbols) showed a significant increase in IOS during exposure to H2O2 while slices incubated with 1 mM taurine (hollow symbols) showed little change in IOS. (B) Taurine concentrations were measured in the effluent of the aCSF that perfused hippocampal slices prepared with 1 mM taurine to maintain normal taurine contents. The taurine concentration in the aCSF perfusate increased significantly at the start of H2O2 exposure and remained elevated for 10 min. * indicates values which are significantly different from the baseline measurements determined prior to H2O2 treatment.