Niels Bohr Institutet > Kalender - det sker på NBI > 2010 > Master thesis defence ...

Master thesis defence by Klaus Bruun Pedersen

Pore theory in pure lipid membranes: From soft perforation to oscillating reversible electrical breakdown under voltage clamp conditions

The movement of ions through the cell membrane is in the literature and in textbooks
explained by the action of protein ion channels. An exception is the field of electroporation. Electroporation is a temporary reversible electrical breakdown induced by lipid channels in the membrane. The lipid channels are caused by large trans membrane voltages, hence the pore models of electroporation are not considered relevant for voltages in the biological regime.

In this thesis I investigate currents through membranes (protein free black lipid membranes) under voltage clamp conditions in the phase transition. I find channel-like events, electroporation events and oscillating reversible electrical breakdown. Theoretically and experimentally, I find that the voltage required for electroporation events such as reversible and irreversible electrical breakdown is lowered in the phases transition of the membrane. I propose, that other electrical phenomena, such as channel-like events and oscillating reversible electrical breakdown, can be explained by the pore models of electroporation. I discuss the ability of two different pore models, to account for channel-like events and oscillating reversible breakdown through a negative feedback mechanism in the voltagepore radius relation. I conclude that both events can be explained by the investigated pore models.