[Lipid pores and stability of cell membranes]

Electric studies have ascertained that transmembrane pores appear during the gel-liquid crystalline transition phase in the bilayer lipid membrane. The longevity of the pore depends on the phase state of lipids: in gel, the pores demonstrate long-term fluctuations, which can be eliminated by heating. The molecular model of a lipid pore has been proposed. The model predicts the formation of pores whose appearance is energetically favourable. The size of a cooperative unit and the area per lipid molecule head have been shown to be responsible for membrane stability. Proceeding from the model, a hypothesis has been forwarded that phase transition may be induced in the lipid bilayer at physiological temperatures. Electric techniques and differential scanning calorimetry have established that bivalent ions of Ca2+, Cd2+, Mg2+, Sr2+, and Ba2+ are able to induce phase transition of bilayer membranes from acid lipids at physiological temperatures to give rise to through pores. An analysis of the experimental findings indicates that pores having a less critical radius themselves adhere with time.