SLC12A1 and chronic kidney disease: In the present study, we measured u-NKCC2, u-AQP2, and u-ENaCγ in CKD patients stage III-IV and healthy controls at baseline and in response to an intravenous volume load of 3.0% hypertonic saline in order to estimate and analyze sodium- and water channel function in patients with CKD compared to healthy controls.