Expression of Na+/Cl-/betaine and Na+/myo-inositol transporters, aldose reductase and sorbitol dehydrogenase in macula densa cells of the kidney.
It has been suggested that macula densa cells may be exposed to hyperosmotic stress. Since chronic exposure to hypertonic stress causes the amount of intracellular organic osmolytes to increase, the expression of transporters and enzymes that participate in the intracellular accumulation of organic osmolytes was examined using non-radioactive in situ hybridization in the macula densa region of control rats and furosemide-treated animals. Both the sodium- and chloride-dependent betaine transporter (BGT) and sodium-dependent myo-inositol transporter (SMIT) were expressed preferentially in macula densa cells and for both mRNAs the signal intensity was visibly reduced by furosemide. The enzymes aldose reductase (which mediates the conversion of glucose to sorbitol) and sorbitol dehydrogenase (which converts sorbitol into fructose) were expressed not only in macula densa cells but also in the surrounding tubular cells, and the expression was insensitive to furosemide. Thus it remains unclear whether the expression of BGT and SMIT is related to a putative hypertonic juxtaglomerular region.
Physiologisches Institut der Universität, Pettenkoferstrasse 12, D-80336 Munich, Germany.
A
A
Burger-Kentischer
E
E
Müller
W
W
Neuhofer
J
J
März
K
K
Thurau
F X
FX
Beck
D000449:Aldehyde Reductase / Q000032:analysis / Q000096:biosynthesis*; D000818:Animals; D001622:Betaine / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D005665:Furosemide / Q000008:administration & dosage / Q000494:pharmacology; D050485:GABA Plasma Membrane Transport Proteins; D005786:Gene Expression Regulation / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D007274:Injections, Intraperitoneal; D007668:Kidney / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000737:chemistry / Q000166:cytology; D007064:L-Iditol 2-Dehydrogenase / Q000032:analysis / Q000096:biosynthesis*; D008297:Male; D008565:Membrane Proteins; D012333:RNA, Messenger / Q000032:analysis / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D027981:Symporters
D002352:Carrier Proteins; D050485:GABA Plasma Membrane Transport Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D027981:Symporters; C072207:betaine plasma membrane transport proteins; C073884:SLC5A3 protein, human; D001622:Betaine; D005665:Furosemide; D007064:L-Iditol 2-Dehydrogenase; D000449:Aldehyde Reductase