Effects of thallium(I) and thallium(III) on liposome membrane physical properties

• Published in: Archives of biochemistry and biophysics Vol. 417; no. 2; pp. 235 - 243
• Main Authors: Villaverde, Marcela S, Verstraeten, Sandra V
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.09.2003
• Subjects: Brain Chemistry; Liposomes - chemical synthesis; Liposomes - chemistry; Macromolecular Substances; Membrane Fluidity; Membrane Fusion; Membrane Potentials; Membrane surface potential; Permeability; Phosphatidylcholines - chemistry; Phosphatidylserines - chemistry; Static Electricity; Surface Properties; Thallium - chemistry; Thallium(I); Thallium(III); Toxicity; Thallium(III); Membrane fluidity; Thallium(I); Membrane surface potential; Toxicity
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/S0003-9861(03)00366-7

The hypothesis that thallium (Tl) interaction with membrane phospholipids could result in the alteration of membrane physical properties was investigated. Working with liposomes composed of brain phosphatidylcholine and phosphatidylserine, we found that Tl +, Tl 3+, and Tl(OH) 3 (0.5–25 μM): (a) increased membrane surface potential, (b) decreased the fluidity of the anionic regions of the membrane, in association with an increased fluidity in the cationic regions, and (c) promoted the rearrangement of lipids through lateral phase separation. The magnitude of these effects followed the order Tl 3+, Tl(OH) 3>Tl +. In addition, Tl 3+ also decreased the hydration of phospholipid polar headgroups and induced membrane permeabilization. The present results show that Tl interacts with membranes inducing major alterations in the rheology of the bilayer, which could be partially responsible for the neurotoxic effects of this metal.