Tl+ influx assay in LLC-PK1 cells. A) Mean signal traces (average from 6 wells) obtained with the fluorometric imaging plate reader (FlexStation). LLC-PK1 cells either mock-transfected or stable transfected with c-NKCC2 construct were shown. Tl+ influx was initiated by Cl- addition. A robust Cl--dependent Tl+ influx was observed in c-NKCC2-transfected but not in mock-transfected LLC-PK1 cells. B) The initial rate of Tl+ influx registered during the assay shown in A was reported. The rate of Tl+ influx was increased by about 3-fold upon c-NKCC2 expression in LLC-PK1 cells. Values are means ± SE of 3 independent experiments. Student’s t test for unpaired data, *p < 0.0001.