Membrane microviscosity

In oitr own studies, we modified membrane microviscosity by incubating nomoal platelets overnight as 22 with cholesterol-rich, cholesterol-normal and cholesterol or liposomes. Under these conditions, and considering only high affinity sites since moderate and low affinity sites were combined in this analysis, the number of receptors was proportional to membrane microviscosity while the affinity at those receptors was inversely proportional to membrane microviscosity (Table 2). 

As ccanpared with modified cholesterol ioimal platelets, the dose response curves for both aggregation and serotonin secretion in response to a-thrombin imderwent a leftward shift using cholesterol-enriched platelets and a rightward shift using cholesterol-depleted 

Not only do these studies support the presence in blood platelets of receptors with two distinct binding affinities but s concept is also supported by earlier functional evidence that thrombin-induced platelet activation is mediated by two distinct pathways which differ in their sensitivity to proteolysis, their requirement for sodium ions, in the need for receptor occupancy and in the role of G proteins (reviewed in ). Furthermore, kinetic studies demonstrated that both ligand-receptor and proteolytic interactions occur in thrombin-induced platelet activation. Thus, foe preponderance of evidence supports foe view that two different types of receptor are involved in foe interaction of thrombin with platelets. The major question is, however, what is foe nature of these two receptors  

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Bagchi M, Hassoun EA, Stohs SJ. 1992a. Endrin-induced increases in hepatic lipid peroxidation, membrane microviscosity, and DNA damage in rats. Arch Environ Contain Toxicol 23 1-5. 

B. R. Lentz, Light scattering effects in the measurement of membrane microviscosity with DPH, Biophys. J. 25, 489-494 (1979). 

The damage to neural membranes induced by ROS has many potential consequences. These include (a) changes in physicochemical properties of neural membranes (microviscosity) resulting in alterations in the orientation of optimal domains for the interaction of functional membrane proteins such as receptors, enzymes, and ion-channels, (b) changes in the number of receptors and their affinity... 

Whitcomb RW, LinehanWM, Knazek RA. Effects of long-chain, saturated fatty acids on membrane microviscosity and adrenocorticotropin responsiveness of human adrenocortical cells in vitro. J Clin Invest 81 185-188,1988. 

Devynck, M-A., Kunes, J., Le Quan Sang, K.-H. and Zicha, J. Membrane microviscosity and plasma... 

Huber LA, Xu QB, Jurgens G, BockG, Buhler E, Gey KF. el al. Correlation of lymphocyte lipid composition, membrane microviscosity and mitogen response in Ihe aged. Eur J Irmnunol 1991 21 2761-2765. 

Keywords antioxidants, Alzheimer s disease, membranes, microviscosity,... 

The EPR-spectroscopy data obtained showed that ichfan applied in various concentrations modifies the microviscosity of both layers (probes I and II) of erythrocyte membranes and EAC cells (Figure 1). We discovered a complex nonlinear character of the dose-effect dependence. In all cases, the membrane microviscosity increased by 18% relative to the control at the HA concentrations 10 16-10 14 M and 10"6-KE M. For EAC cells, under the action of the compound, the microviscosity of both layers of the membrane lipid bilayer decreased on the average by 20% with the exception of the extreme concentrations. Consequently, in vitro experiments showed that ichfan modifies the structural state of biomembranes the effect depends on the compound dose and type of membranes. 

For EAC cells membranes, the compound (almost over the entire concentration range) decreases significantly the microviscosity of surface lipids and near-protein domains of the lipid bilayer only at the HA concentrations 10"16 and 10"4 M, the viscosity increases. In particular, the compound dose 10"5 M affects the Ca2+ signal system of EAC cells. At lower ichfan concentrations (10 8 M), the membrane microviscosity decreases and the compound produces no effect on the cell volume. Evidently, over this concentration range, the compound produces no effect on the membrane and Ca2+ signal system. 

The drug (31) is to be effective in infiuencing the rheological measures of red cell filteribility and membrane microviscosity filteribility was increased and microviscosity was decreased. 

The dependence of x 16-DSAon the concentrations of IM-DPhO is presented in Fig. 3 (curve 2). In the case of IM-DPhO the most increase of microviscosity value is about 13% at the concentration of 10 mol/1, and the constant value observed within concentration range l(f -10 mold (effect is about 10%). A comparison of the effects of two oxazoles on the lipid membrane microviscosity results to a conclusion that the effect... 

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