NDLI: Alternative channels for urea in the inner medulla of the rat kidney.

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Nawata, C. Michele Dantzler, William H. Pannabecker, Thomas L.
Description	Author Affiliation: Nawata CM ( Department of Physiology, University of Arizona Health Sciences Center, Tucson, Arizona cmnawata@email.arizona.edu.); Dantzler WH ( Department of Physiology, University of Arizona Health Sciences Center, Tucson, Arizona.); Pannabecker TL ( Department of Physiology, University of Arizona Health Sciences Center, Tucson, Arizona.)
Abstract	The ascending thin limbs (ATLs) and lower descending thin limbs (DTLs) of Henle's loop in the inner medulla of the rat are highly permeable to urea, and yet no urea transporters have been identified in these sections. We hypothesized that novel, yet-unidentified transporters in these tubule segments could explain the high urea permeability. cDNAs encoding for Na(+)-glucose transporter 1a (SGLT1a), Na(+)-glucose transporter 1 (NaGLT1), urea transporter (UT)-A2c, and UT-A2d were isolated and cloned from the Munich-Wistar rat inner medulla. SGLT1a is a novel NH2-terminal truncated variant of SGLT1. NaGLT1 is a Na(+)-dependent glucose transporter primarily located in the proximal tubules and not previously described in the thin limbs. UT-A2c and UT-A2d are novel variants of UT-A2. UT-A2c is truncated at the COOH terminus, and UT-A2d has one exon skipped. When rats underwent water restriction for 72 h, mRNA levels of SGLT1a increased in ATLs, NaGLT1 levels increased in both ATLs and DTLs, and UT-A2c increased in ATLs. [(14)C]urea uptake assays performed on Xenopus oocytes heterologously expressing these proteins revealed that despite having structural differences from their full-length versions, SGLT1a, UT-A2c, and UT-A2d enhanced urea uptake. NaGLT1 also facilitated urea uptake. Uptakes were Na(+) independent and inhibitable by phloretin and/or phloridzin. Our data indicate that there are several alternative channels for urea in the rat inner medulla that could potentially contribute to the high urea permeabilities in thin limb segments.
File Format	HTM / HTML
ISSN	1931857X
Issue Number	11
Volume Number	309
e-ISSN	15221466
Journal	AJP: Renal Physiology
Language	English
Publisher	American Physiological Society
Publisher Date	2015-12-01
Publisher Place	United States
Access Restriction	Subscribed
Subject Keyword	Xenopus Research Support, N.i.h., Extramural Rats, Wistar Molecular Sequence Data Male Dehydration Oocytes Antagonists & Inhibitors Journal Article Discipline Physiology Osmolar Concentration Biological Transport Time Factors Genetics Female Transcription, Genetic Amino Acid Sequence Loop Of Henle Rna, Messenger Gene Expression Regulation Discipline Nephrology Sodium-glucose Transporter 1 Pharmacology Permeability Metabolism Drug Effects Membrane Transport Modulators Urea Animals Membrane Transport Proteins Kidney Medulla
Content Type	Text
Resource Type	Article
Subject	Physiology Urology

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