Role of renal transporters in accumulation of Hg-(GSH)2 in BLM vesicles from control and NPX rat kidney(s). Net accumulation of Hg-(GSH)2 conjugate in BLM vesicles was determined by incubating vesicles with a pre-equilibrated solution of 20 μM HgCl2 and 60 μM GSH, containing 203Hg2+, in the presence and absence of Na+ ions. When Na+ ions were present, potential competing substrates were added at a final concentration of 500 μM. Binding was subtracted from total intravesicular contents to give net uptake. Results, which indicate uptake in the absence of Na+ ions (−Na+), total uptake in the presence of Na+ ions (+Na+), and the Na+-dependent component of uptake, are expressed as nmol Hg2+/mg protein per 30 s and are means ± SE of measurements from separate membrane vesicle preparations from three control and three NPX rats. aStatistically significant difference (p < 0.05) from the corresponding sample incubated with buffer. bStatistically significant difference (p < 0.05) from the corresponding sample incubated in the absence of Na+ ions. cStatistically significant difference (p < 0.05) from the corresponding sample from BLM vesicles from control rat kidneys.