[Effect of phenothiazines on the viscosity and electrical stability of model phospholipid membranes].

The effect of five phenothiazine derivatives on the viscosity of model phospholipid membranes (by eximerization of pyrene) and on their electrical stability has been studied All the phenothiazines tested (chlorpromazine, propazine, triftazin and nonachlazine), except for chloracyzine, considerably increase the viscosity of phospholipid liposome bilayer at a concentration of 10(-5)-10(-4) M. Phenothiazines have been also shown to decrease liposome break-down potential even at a concentration of 10(-7) M. No correlation between the magnitude of break-down potential and changes in liposome membrane viscosity has been revealed.

Electrical stability of artificial membranes.

The electrical breakdown potential of the planar lipid membranes has been shown to decrease following UV-induced lipid peroxidation, action of phospholipase A2, adsorption of protamine sulphate and expansion of the membrane by hydrostatic pressure. Membrane potential generated upon the addition of potassium acetate (or ammonium sulphate) and protonophore CCCP to liposomes, when large enough, was also able to break membranes; this was suggested by liposome swelling and a rapid decrease in suspension turbidity. UV-irradiation decreased liposomal membrane breakdown potential, while cholesterol increased it.

[Electrical stability of mitochondrial membranes: the role of thyroid hormones and the fat component of the diet].

Electric stability of the membranes of the mitochondria and liposomes formed from mitochondrial lipids was studied. The mitochondria were isolated from the liver of euthyroid or hyperthyroid rats kept on the diets with varying degree of food fat unsaturation. In the first group animals, butter was used as a fatty component of the diet whereas the second group animals received sunflower oil.

[Thyroid hormones and the electrical stability of rat liver mitochondrial membranes].

The electrical stability of mitochondrial membranes isolated from the liver of normal, hypothyroid, hyperthyroid (0.1 mg L-thyroxine per 100 g bw for 9 days) and thyrotoxic (4 mg L-thyroxine per 100 g bw for 6 days) rats was investigated. The electrical stability of mitochondrial membranes was estimated by the amount of potassium acetate required for electrical breakdown of the mitochondria.

[Electric stability of liposome membranes in UV-induced lipid peroxidation].

It has been shown that UV-induced peroxide oxidation of lipids (POL) and its water-soluble products similarly affect the liposomes of egg lecithin and mitochondrial lipids; they decrease the electric stability of the membranes, and aggregation ability of vesicles and increase proton permeability of the membranes. Possible mechanism of the increase of membrane ionic permeability during POL is discussed.