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Biochim Biophys Acta. 1998 Apr 22;1371(1):129-33.

Independence of dimethylamiloride-sensitive Li+ efflux pathways and Na+-Li+ countertransport in human erythrocytes.

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1
Renal Pathophysiology Laboratory, Division of Medicine, Scientific Institute San Raffaele, University of Milan, Milan I-20132, Italy.

Abstract

The in vivo function of the erythrocyte Na+-Li+ countertransport (SLC) is unknown. Whether SLC may reflect an operational mode of the widespread Na+-H+ exchanger (NHE) or may otherwise be expression of an independent membrane transport, remains presently unclear. We explored the presence of 5-(N,N-dimethyl)-amiloride (DMA)-sensitive Li+ pathways in human erythrocytes where the activity of the Na+ pump, Na+-K+ cotransport and anion exchange were suitably inhibited. A total of 0.02 mM DMA had no effect on SLC as expected, but gave a significant inhibition of Li+ efflux into both Na+ and Na+-free media. This DMA-sensitive Li+ pathway, but not SLC, was significantly enhanced by hyperosmolar cell shrinkage, which is a characteristic feature of NHE. In conclusion, DMA-sensitive Li+ pathways, possibly mediated by NHE, are present in erythrocytes and coexist with the DMA-insensitive, SLC. This finding supports the notion that SLC is independent of amiloride-sensitive NHE.

PMID:
9565666
DOI:
10.1016/s0005-2736(98)00012-1
[Indexed for MEDLINE]
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