Jehle, A W; Forgo, J; Biber, J; Lederer, E; Krapf, R; Murer, H (1997). Acid-induced stimulation of Na-Pi cotransport in OK cells: molecular characterization and effect of dexamethasone. American Journal of Physiology: Renal Physiology, 273(3 Pt 2):F396-F403.
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Alterations in systemic acid/base balance affect renal Pi excretion. In the present study, the effects of an acidic pH on apical Na-dependent Pi (Na-Pi) cotransport were analyzed using OK cells (opossum kidney cell line). Cells were maintained at either pH 7.4 or 7.1 (altered HCO3- concentration at constant PCO2). Incubation in acidic medium led to an increase in Na-Pi cotransport activity, which was characterized by a transient, initial response (2-4 h, 25% increase) followed by a sustained response (24 h, 75% increase). Increased Na-Pi cotransport activity (24 h) was sensitive to inhibition by parathyroid hormone. Actinomycin D did not abolish the acid-induced increases (initial and sustained responses). Cycloheximide abolished the increase in Na-Pi cotransport observed after 24 h. The increase in Na-Pi cotransport (24 h) was prevented by dexamethasone (2 x 10(-6) M). Western blots showed a twofold (3 h) and two- to threefold (24 h) increase in NaPi-4 protein after acid exposure. Cycloheximide prevented the late increase in NaPi-4 protein abundance. Also dexamethasone reduced the increase in specific protein content. In conclusion, the exposure of OK cells to an acidic medium causes a stimulation of the NaPi-4 cotransporter that is prevented by dexamethasone.
|Item Type:||Journal Article, refereed|
|Communities & Collections:||04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
|Dewey Decimal Classification:||570 Life sciences; biology|
|Date:||1 September 1997|
|Deposited On:||11 Feb 2008 12:22|
|Last Modified:||27 Nov 2013 20:26|
|Publisher:||American Physiological Society|
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