Assessment of Uncoupling by Amiloride Analogs

Kelvin Davies, Marc Solioz

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


The amiloride analogs N5-methyl-N5-isobutylamiloride, N5-ethyl-N5-isopropylamiloride, and N5,N5-hexamethyleneamiloride are frequently used to investigate NaH exchange on the premise that they are highly specific inhibitors of the NaH-antiporters. We assessed the relative protonophoric activity of these compounds in reconstituted and native membrane vesicles, using acridine orange fluorescence to measure intravesicular pH. All the compounds tested were found to be potent protonophores at concentrations which are normally used to demonstrate inhibition of NaH exchange. Uncoupling was dependent on both the pH of the assay system and the total amount of lipid present. At the pH optima, which lay in a range from 7.5 to 8.5, these amiloride analogs were more potent uncouplers than the classical protonophore carbonyl cyanide m-chlorophenylhydrazone. Therefore, extreme care must be taken in the interpretation of results obtained using these or similar derivatives of amiloride.

Original languageEnglish (US)
Pages (from-to)8055-8058
Number of pages4
Issue number34
StatePublished - Feb 1 1992
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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