[Aggregation of cardiolipin liposomes induced by monovalent cations]

Monovalent ion induced aggregation of the cardiolipin bilayer liposomes is studied. Derived threshold concentrations (Ck) stimulating fast aggregation testify that the order of effectiveness for monovalent cations to cause this process is: H+ greater than Na+ greater than Li+ greater than K+. The Ck is shown to be nonmonotonously dependent on the temperature discovering a maximum in the range approximately 30-40 degrees C. It is also shown that the liposomes preliminary temperature processing for two hours at approximately 70 degrees C as well as the liposomes incubation for several days at approximately 5 degrees C affect the Ck value. In both cases a considerable Ck increase is accompanied by almost two-fold increase of the lipid oxidation index. The studied process is reversible to both electrolyte concentration dilution and temperature changes. However, unlike the phosphatidylserine (PS) and phosphatidic acid (PA) liposomes the observed changes in the cardiolipin case proceeding considerably slower possibly indicate that the potential must be lower in its depth than that in the case of PS and/or PA.