Potassium restriction downregulates ROMK expression in rat kidney.
The ROMK family of proteins has biophysical properties and distribution within the kidney similar to those of secretory potassium channels of the distal nephron. To study the regulation of ROMK during variations in dietary potassium, we measured the abundance of ROMK protein in rat kidney by immunoblotting. Neither 2 nor 5 days of a high-potassium diet had an effect on protein abundance in the cortex or medulla. Potassium deprivation (2 or 5 days) decreased ROMK protein content in both cortical and medullary fractions, to 51 and 40% of controls, respectively. To see whether the Na-K-2Cl cotransporter is similarly affected by potassium restriction, we analyzed immunoblots by using an antibody for the rat type 1 bumetanide-sensitive cotransporter (BSC-1). Like ROMK, BSC-1 protein content was found to decrease significantly in the renal medulla of potassium-deprived rats. In the thick ascending limb of Henle's loop, a decrease in ROMK and BSC-1 could result in decreased reabsorption of NaCl, a finding associated with hypokalemia.
Mennitt
P A
PA
Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY 10021, USA.
Frindt
G
G
Silver
R B
RB
Palmer
L G
LG
D000818:Animals; D000918:Antibody Specificity; D002352:Carrier Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D007150:Immunohistochemistry; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D017419:Potassium, Dietary / Q000008:administration & dosage; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D028021:Sodium-Potassium-Chloride Symporters
D002352:Carrier Proteins; C510692:Kcnj1 protein, rat; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D017419:Potassium, Dietary; D012333:RNA, Messenger; D028021:Sodium-Potassium-Chloride Symporters; D011188:Potassium