The interaction of the divalent calcium ions with the zwitterionic lipid membranes was studied by measuring the lipid order parameter which is inversely proportional to the membrane fluidity. Small unilamellar lipid vesicles were prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and then treated with different concentrations of divalent calcium ions. An increase in the order parame...

The effect of ticlopidine on platelet membrane fluidity was investigated using a spin label technique. Ticlopidine, when orally administered to rats, increased both the order parameter and the motion parameter, indicating a decrease in the membrane fluidity of platelets. On the other hand, the order parameter and the motion parameter decreased markedly when the platelets were aggregated by thro...

Cholesteryl hemisuccinate has been incorporated into pea chloroplast thylakoids to investigate the relationship between fluidity and functioning of this membrane system. Levels of sterol which increased the apparent viscosity of the membrane, estimated by fluorescence polarization measurements using the lipophilic probe, 1,6-diphenyl-1,3,5 hexatriene, affected several photosynthetic processes. ...

AIM To test whether membrane fluidity and its changes are important for the sensitivity of cells to the action of perifosine (OPP), a new anticancer drug targeting cell membrane and not DNA. METHOD Influence of OPP on the membrane structure of OPP-resistant MCF7, and OPP-sensitive MT3 breast cancer cell lines, as well as of mouse fibroblasts (L929) cell lines, and model cells (liposomes) was ...

The lipid composition of erythrocytes (red blood cells [RBCs]) plays a significant role in determining certain membrane biophysical properties. We have found that fetal RBCs showed a dramatically low filterability compared with adult RBCs and questioned whether this could be a consequence of their membrane lipid composition. We therefore studied fetal RBCs at two different gestational ages, neo...

To determine a possible role of sodium-potassium adenosine triphosphatase (Na+, K+-ATPase) in the regulation of membrane functions in hypertension, we investigated the effects of ouabain on the membrane fluidity of erythrocytes in spontaneously hypertensive rats (SHR) by means of an electron paramagnetic resonance (EPR) and spin labeling method. Erythrocytes obtained from SHR were examined comp...

Treatment of living entamoeba histolytica cells with low concentrations of concanavalin A (con A) and peroxidase results in redistribution of the plasma membrane con A receptors to one pole of the cell where a morphologically distinct region--the uroid--is formed. Capping of con A receptors is not accompanied by parallel accumulation of ruthenium red-stainable components. In capped cells, the p...

The solubility of the spin label TEMPO (I) in membranes depends on the fluidity of the membrane. An empir ical relat ionship has been establ ished between TEMPO solubility and fluidity, measured by the order parameter S~o. This relationship is employed to determine the fract ion of the lipid in membranes of rabbit muscle sarcoplasmic re t iculum that is in a fluid state. We find that 84% of the...

It is well known that cellular cultures grown at different temperatures will display altered membrane lipid composition to maintain a relatively constant membrane fluidity across a range of temperatures. One of the proposed theories on the mechanism of chemically-induced transformation is that a higher temperature of the heat-shock step increases the fluidity of the host cell membrane, allowing...