Abstract |
Chronic hypokalemia increases the activity of proximal tubule apical membrane Na+/H+ antiporter NHE3. The present study examined the effect of the incubation of OKP cells (an opossum kidney, clone P cell line) in control medium (K+ concn ([K+]) = 5.4 mM) or low-K+ medium ([K+] = 2.7 mM) on NHE3. The activity of an ethylisopropyl amiloride-resistant Na+/H+ antiporter, whose characteristics were consistent with those of NHE3, was increased in low-K+ cells beginning at 8 h. NHE3 mRNA and NHE3 protein abundance were increased 2.2-fold and 62%, respectively, at 24 h but not at 8 h. After incubation in low-K+ medium, intracellular pH (pHi) decreased by 0.27 pH units (maximum at 27 min) and then recovered to the control level. Intracellular acidosis induced by 5 mM sodium propionate increased Na+/H+ antiporter activity at 8 and 24 h. Herbimycin A, a tyrosine kinase inhibitor, blocked low-K+- and sodium propionate-induced activation of the Na+/H+ antiporter at 8 and 24 h. Our results demonstrate that low-K+ medium causes an early decrease in pHi, which leads to an increase in NHE3 activity via a tyrosine kinase pathway.
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Authors | M Amemiya, K Tabei, E Kusano, Y Asano, R J Alpern |
Journal | The American journal of physiology
(Am J Physiol)
Vol. 276
Issue 3
Pg. C711-6
(03 1999)
ISSN: 0002-9513 [Print] United States |
PMID | 10069999
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Acids
- Culture Media
- RNA, Messenger
- Sodium-Hydrogen Exchanger 3
- Sodium-Hydrogen Exchangers
- Hydrogen
- Protein-Tyrosine Kinases
- Potassium
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Topics |
- Acids
(metabolism)
- Animals
- Cell Line
- Culture Media
(chemistry, pharmacology)
- Hydrogen
(metabolism)
- Hydrogen-Ion Concentration
- Intracellular Membranes
(metabolism)
- Kidney
(cytology, drug effects, metabolism)
- Opossums
- Potassium
(administration & dosage, pharmacology)
- Protein-Tyrosine Kinases
(metabolism)
- RNA, Messenger
(metabolism)
- Sodium-Hydrogen Exchanger 3
- Sodium-Hydrogen Exchangers
(genetics, metabolism)
- Time Factors
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