Chronic hypokalemia enhances expression of the h+-k+-atpase
[alpha]2 subunit gene in renal medulla.
Ahn, Kyu Y., K. K. Kim, and Bruce C. Kone.
Departments of Internal Medicine and Integrative Biology, The
University of Texas Medical School at Houston, Houston, TX 77030, and
Department of Anatomy, Chonnam University Medical School, Kwangju,
Korea, 501-190
APStracts 3:0051F, 1996.
Chronic Hypokalemia Enhances Expression of the H+-K+-ATPase [alpha]2
Subunit Gene in Renal Medulla. Recent molecular and physiological
studies suggested that at least two H+-K+-ATPase isoenzymes are
expressed in the rat kidney, and that these ion pumps respond to
changes in dietary potassium balance. We used Northern analysis and
in situ hybridization to analyze the expression of mRNA encoding the
OcolonicO isoform of the H+-K+-ATPase [alpha] subunit (HK[alpha]2) in
normal and potassium-deprived (2 weeks) rats. Control rats exhibited
low levels of HK[alpha]2 mRNA in the cortical and medullary thick
ascending limb, distal convoluted tubule, connecting segment, and the
entire collecting duct. The potassium-deprived rats expressed [sim]
5-fold higher levels of HK[alpha]2 mRNA in the outer and inner
medulla compared to controls, and hypertrophy and increased in situ
hybridization signal in the intercalated cells of the outer medullary
collecting ductinner stripe and the proximal inner medullary
collecting duct. In contrast, renal cortical expression of HK[alpha]2
mRNA was low and comparable in the two groups. Our results suggest
that enhanced expression of the HK[alpha]2 subunit gene in the renal
medulla contributes to potassium conservation during chronic
hypokalemia.
Received 12 December 1995; accepted in final form 1 March 1996.
APS Manuscript Number F408-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96