Echinococcus granulosus: Partial Characterization of the Conductive Properties of Two Cation Channels from Protoscoleces of the Ovine Strain, Reconstituted on Planar Lipid Bilayers

Claudio Grosman, Ignacio L. Reisin

Research output: Contribution to journalArticlepeer-review

Abstract

Two cationic channels present in the microsomal fraction from Echinococcus granulosus protoscoleces of the sheep strain were studied in planar bilayer reconstitution experiments. A whole-worm homogenate was subjected to differential centrifugation and the postmitochondrial supernatant was laid on the top of a discontinuous sucrose gradient. The 15-30% (w/v) membrane fraction, enriched in NADPH-cytochrome c reductase, exhibited the highest fusion rate, two cationic channels being most frequently reconstituted. Both of them were highly cation-selective and had high conductances (244 and 107 pS in symmetrical 150 mM KCl). In most experiments, none of them displayed voltage dependence. The 244-pS channel was activated by Ca2+ and blocked by Ba2+, both in the micromolar range, thus partially resembling the Ca2+-activated K+ channel from more highly evolved animals. The 107-pS channel exhibited a Cs+ ≅ K+ > Na+ > Li+ > Ca2+ selectivity sequence (as measured by permeability ratios) and, most frequently, a high open probability (>0.9) irrespective of the experimental conditions used, therefore sharing many properties of Schistosoma mansoni outer tegumental membrane cation channels.

Original languageEnglish (US)
Article number71148
Pages (from-to)546-555
Number of pages10
JournalExperimental Parasitology
Volume81
Issue number4
DOIs
StatePublished - Dec 1995
Externally publishedYes

ASJC Scopus subject areas

  • Parasitology
  • Immunology
  • Infectious Diseases

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