Inhibition of FL accumulation by glutathione and a size range of its conjugates. Inhibition of FL accumulation by glutathione and a size range of its conjugates. All inhibitor concentrations are 0.2 mmol l–1; sample sizes are 6 tubules, except for `no inhibitor, which represents all control trials (N=23). *Change in uptake rate (second measurement period relative to first measurement period) in presence of inhibitor significantly different from uptake rate in absence of inhibitor; P<0.05, paired t-test. Douglas S. G. Neufeld et al. J Exp Biol 2005;208:2227-2236 © The Company of Biologists Limited 2005