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Aldosterone Activates Na+/H+ Exchange and Raises Cytoplasmic pH in Target Cells of the Amphibian Kidney
H. Oberleithner, M. Weigt, H.-J. Westphale and W. Wang
Proceedings of the National Academy of Sciences of the United States of America
Vol. 84, No. 5 (Mar. 1, 1987), pp. 1464-1468
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/29220
Page Count: 5
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The hypothesis was tested if the mineralocorticoid hormone aldosterone stimulates Na+/H+ exchange in ``giant cells'' fused from individual target cells of the distal nephron of the frog kidney. By means of microelectrodes, steady-state intracellular pH (pHi) and pHi recovery from an acid load were recorded continuously while the fused cells were exposed to aldosterone. Twenty minutes after addition of the hormone, pHi) started to rise and reached a new steady state after about 60 min (Δ pHi = 0.28 ± 0.01). After hormone treatment, pHi recovered significantly faster in response to an intracellular acid load. The diuretic drug amiloride blocked pHi recovery. Experiments in intact tubules showed that aldosterone induces H+ and K+ secretion. Thus, intracellular alkalosis, mediated by Na+/H+ exchange, could serve as a signal that activates pH-sensitive K+ channels of the luminal cell membrane.
Proceedings of the National Academy of Sciences of the United States of America © 1987 National Academy of Sciences