Transport properties of the calcium ionophore ETH-129.

Published

Journal Article

The transport mechanism and specificities of ionophore ETH-29 have been investigated in a highly defined phospholipid vesicle system, with the goal of facilitating the application of this compound to biological problems. ETH-129 transports Ca(2+) via an electrogenic mechanism, in contrast to A23187 and ionomycin, which function in a charge neutral manner. The rate of transport is a function of membrane potential, increasing by 3.9-fold per 59 mV over a broad range of that parameter. Rate is independent of the transmembrane pH gradient and strongly stimulated by the uncoupler carbonyl cyanide m-chlorophenylhydrazone when no external potential has been applied. The effect of uncoupler reflects the collapse of an opposing potential arising during Ca(2+) transport, but also reflects the formation of a mixed complex between the uncoupler, ETH-129, and Ca(2+) that readily permeates the vesicle membrane. Oleate does not substitute for the uncoupler in either regard. ETH-129 transports polyvalent cations according to the selectivity sequence La(3+) > Ca(2+) > Zn(2+) approximately equal to Sr(2+) > Co(2+) approximately equal to Ni(2+) approximately equal to Mn(2+), with the magnitude of the selectivity coefficients reflecting the cation concentration range considered. There is little or no activity for the transport of Na(+), K(+), and Mg(2+). These properties suggest that ETH-129 will be useful for investigating the consequences of a mitochondrial Ca(2+) overload in mammalian cells, which is difficult to pursue through the application of electroneutral ionophores.

Full Text

Duke Authors

Cited Authors

  • Wang, E; Erdahl, WL; Hamidinia, SA; Chapman, CJ; Taylor, RW; Pfeiffer, DR

Published Date

  • December 2001

Published In

Volume / Issue

  • 81 / 6

Start / End Page

  • 3275 - 3284

PubMed ID

  • 11720991

Pubmed Central ID

  • 11720991

International Standard Serial Number (ISSN)

  • 0006-3495

Digital Object Identifier (DOI)

  • 10.1016/S0006-3495(01)75961-9

Language

  • eng

Conference Location

  • United States