Tl+ influx assay for c-NKCC2 activity in c-NKCC2-expressing LLC-PK1 cells. A) Mean signal traces (average from 6 wells) from c-NKCC2 expressing LLC-PK1 in the absence (CTR) or in the presence of 50 μM Furosemide during the assay (Furo) were shown. The Tl+ influx was inhibited in the presence of Fuorsemide. B) The initial rate of Tl+ influx deduced from the assay shown in A was reported. The Tl+ flux rate was inhibited by about 3 fold in the presence of 50 μM Furosemide. Values are means ± SE of 3 independent experiments. Student’s t test for unpaired data, *p < 0.0001.