AJP - Gastrointestinal and Liver Physiology, Vol 259, Issue 5 842-G849, Copyright © 1990 by American Physiological Society

ARTICLES

Amiloride and analogues inhibit Na(+)-H+ exchange and cell proliferation in AR42J pancreatic cell line

M. Delvaux, M. J. Bastie, J. Chentoufi, E. J. Cragoe Jr, N. Vaysse and A. Ribet
Institut National de la Sante et de la Recherche Medicale, U151, CHU de Rangueil, Toulouse, France.

To study the relation between activation of the Na(+)-H+ antiporter and gastrointestinal cell proliferation, we characterized this antiporter in a pancreatic cell line (AR42J) and studied the effects of mitogenic and nonmitogenic agents as well as those of Na(+)-H+ exchange blocking agents on DNA synthesis. Characteristics of amiloride-sensitive Na+ uptake were those of the Na(+)-H+ exchanger: 1) Na+ uptake was increased by intracellular acidification and depended on external [Na+] and pH; 2) concentrations for half-maximal inhibition (IC50) of Na+ uptake (3 mM [Na+] in medium) were 40 nM 5-(N,N-hexamethylene)amiloride (HA) less than 0.1 microM 5-(N-ethyl-N-isopropyl)amiloride (EIPA) less than 1 microM 5-(N,N-dimethyl)-amiloride (DMA) less than 40 microM amiloride; 3) IC50 for amiloride and analogues to inhibit Na+ uptake depended on [Na+] in medium (in 25 mM Na+ medium, the IC50 values were higher than in 3 mM and were 1 microM EIPA less than 10 microM DMA less than 0.3 mM amiloride). Growth factors for AR42J cells (dialyzed fetal calf serum and epidermal growth factor) activated Na+ uptake in a dose-dependent manner. Bombesin, which is nonmitogenic for AR42J cells, also increased Na+ uptake, indicating that activation of the antiporter is not sufficient to initiate cell proliferation in the AR42J cell line. The effects of Na(+)-H+ exchange blocking agents were tested on serum-stimulated cell proliferation. Decreasing external Na+ dramatically decreased AR42J cell proliferation. Amiloride and analogues inhibited [3H]thymidine incorporation in the same range of concentrations as that with which they inhibited Na(+)-H+ exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

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