Effects of chronic hypokalemia on renal expression of the "gastric" H(+)-K(+)-ATPase alpha-subunit gene.
Chronic potassium restriction leads to active potassium reabsorption in the late distal nephron and collecting duct, segments known to express "gastric" H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) alpha-subunit mRNA. In this study, the cellular distribution and relative abundance of mRNA encoding this isoform were examined in kidneys of normal and potassium-deprived (2 wk) rats. In situ hybridization with isoform-specific cRNA probes demonstrated prominent expression of this gene in the connecting segment (CNT), entire collecting duct, and renal papillary surface epithelium in a comparable distribution in both groups of rats. Hypertrophy of the outer medullary collecting ducts in the inner stripe of potassium-restricted rats was observed. Competitive polymerase chain reaction analysis revealed twofold greater levels of gastric H(+)-K(+)-ATPase alpha-subunit mRNA (normalized to the level of beta-actin mRNA) in the cortex, but roughly comparable levels in the outer and inner medulla, of potassium-restricted rats compared with controls. These data suggest that chronic potassium restriction results in modestly enhanced renal cortical expression of the gastric H(+)-K(+)-ATPase alpha-subunit gene and that this isoform may participate in potassium conversation by the CNT and cortical collecting duct during potassium deprivation.
Ahn
K Y
KY
Department of Internal Medicine, University of Texas Health Science Center at Houston 77030, USA.
Turner
P B
PB
Madsen
K M
KM
Kone
B C
BC
D000818:Animals; D002908:Chronic Disease; D005260:Female; D015870:Gene Expression; D017506:H(+)-K(+)-Exchanging ATPase / Q000235:genetics*; D007008:Hypokalemia / Q000201:enzymology* / Q000235:genetics; D007668:Kidney / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D011191:Potassium Deficiency / Q000201:enzymology / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013270:Stomach / Q000201:enzymology*
D012333:RNA, Messenger; D017506:H(+)-K(+)-Exchanging ATPase