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

Autor: I. L. Reisin, Claudio Grosman
Rok vydání: 1995
Předmět:
Zdroj: Experimental Parasitology. 81:546-555
ISSN: 0014-4894
DOI: 10.1006/expr.1995.1148
Popis: 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 Ca 2+ and blocked by Ba 2+ , both in the micromolar range, thus partially resembling the Ca 2+ -activated K + channel from more highly evolved animals. The 107-pS channel exhibited a Cs + ≅ K + > Na + > Li + > Ca 2+ 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.
Databáze: OpenAIRE
Externí odkaz: