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Hyperosmotic NaCl and Urea Synergistically Regulate the Expression of the UT-A2 Urea Transporter in Vitro and in Vivo

2000; Elsevier BV; Volume: 271; Issue: 2 Linguagem: Inglês

10.1006/bbrc.2000.2640

1090-2104

Christine Leroy, Gilles J. Basset, Gaëtan Gruel, Pierre Ripoche, Marie‐Marcelle Trinh‐Trang‐Tan, Germain Rousselet,

Electrolyte and hormonal disorders

The UT-A2 urea transporter is involved in the recycling of urea through the kidney, a process required to maintain high osmotic gradients. Dehydration increases UT-A2 expression in vivo. The tissue distribution of UT-A2 suggested that hyperosmolarity, and not vasopressin, might mediate this effect. We have analyzed the regulation of UT-A2 expression by ambiant osmolarity both in vitro (mIMCD3 cell line) and in vivo (rat kidney medulla). The UT-A2 mRNA was found to be synergistically up-regulated by a combination of NaCl and urea. Curiously, the UT-A2 protein was undetectable in this hypertonic culture condition, or after transfection of the UT-A2 cDNA, whereas it could be detected in HEK-293 transfected cells. Treating rats with furosemide, a diuretic which decreases the kidney interstitium osmolarity without affecting vasopressin levels, led to decreased levels of the UT-A2 protein. Our results show that the UT-A2 urea transporter is regulated by hyperosmolarity both in vitro and in vivo.