The role of membrane potential dynamics in cell behaviours:investigating the membrane potential dynamics in the Jurkat and HMEC-1 cell lines using the continuous wavelet transform

摘要

The role of the plasma membrane potential is most commonly associated with the generation of action potentials in excitable cells, however, experimental evidence suggests that this membrane potential is also linked to various behaviours in all cells (Blackiston et al., 2009). These cell behaviours include cell proliferation, cell migration and even cell survival. The membrane potential has been thought to influence these cell behaviours upstream of the classical transduction pathways. Recent evidence suggests that the membrane potential is dynamic rather than static and this dynamic behaviour may encode information on cell behaviours. The whole cell patch clamping technique coupled with the continuous wavelet transform (CWT) technique was used to investigate the presence of fluctuations and oscillations in the membrane potential of Jurkat cells and HMEC-1 cells. The underlying nature of the membrane potential dynamics of Jurkat cells was investigated by perturbing the extracellular concentration of either K+ , Na+ or Cl- . The membrane potential dynamics of proliferating, non-proliferating and activated Jurkat cells was investigated by either varying the culture medium or treating the cells with the concavalin A mitogen. The membrane potential dynamics of HMEC-1 endothelial cells was also investigated. The magnitude of the static membrane potential of proliferating Jurkat cells was significantly more depolarised that non-proliferating Jurkat cells – a trend which has been observed in a wide range of cell types. The membrane potential dynamics appear to be driven by the conductance of ions rather than the magnitude of the static membrane potential per se. In summary, this thesis has proven that the membrane potential varies with cell state and the CWT technique can be used to interrogate recordings of the membrane potential to ascertain information on the membrane potential dynamics that cannot be currently determined by other techniques.