| Popis: |
Ions play a vital role in numerous biological processes including myoblast membrane fusion. We have recently demonstrated that cesium ions delay the sharp decrease in both membrane conductivity and membrane permittivity of chick embryo myoblasts seen at fusion [M.T. Santini, A. Bonincontro, C. Cametti and P.L. Indovina, Biochim. Biophys. Acta, 945 (1988) 56–64]. Analysis of the conductivity dispersion data (obtained in the radio-frequency range) indicated that cesium delays fusion by ca. 30 hr. Since this ion is known to block potassium channels, the fusion delay appears to be due to interference with the sodium/potassium equilibrium. In the present study, we have concentrated our efforts on trying to understand the role of ions during myoblast fusion in a more detailed manner. Specifically, the effects of sodium, potassium and various concentrations of cesium on myoblast fusion were investigated. Our data indicate that addition of sodium has no effect on membrane fusion, whereas potassium delays this process by about 10 hr. In addition, different concentrations of cesium delay myoblast membrane fusion in a concentration-dependent manner. We discuss the possible mechanisms by which these ions perturb the sodium/potassium equilibrium and, consequently, the fusion process. |
