The kinetics of 99mTc-ECD in the brain and the metabolic rate of 99mTc-ECD in mice brain homogenates. (A) The kinetics of 99mTc-ECD in the brain. (B) Typical analytical image of radioactivity on a thin-layer chromatography (TLC) plate in the measurement of metabolic rate (control, 0.243 g/mL; Oat3−/−, 0.237). (C) Time-dependent metabolism of 99mTc-ECD in mice brain homogenates shown in (B) (closed, control; open, Oat3−/−). Regression curves based on first-order kinetics are presented. 99mTc-ECD, 99mTc complex with N,N'-1,2-ethylenediylbis-L-cysteine diethyl ester; Oat3, organic anion transporter 3.