Membrane microviscosity and

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. 

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. 

Lipids Peroxidation of fatty acids, decrease in neural membrane fluidity, permeability, microviscosity, and activities of membrane-bound enzymes (Farooqui and Horrocks, 2007)... 

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... 

Both suicidal behavior and impulsive aggression have been associated with low levels of brain serotonergic activity [91, 92]. Engelberg suggested that a reduction in serum cholesterol may decrease brain-cell-membrane cholesterol, lower lipid microviscosity, and decrease exposure of protein serotonin receptors on the membrane surface, thus resulting in a poorer uptake of serotonin from the blood and less serotonin entry into brain cells [4]. Other reports have discussed the relationships between cholesterol, serotonin, and depression [6, 93-96]. 

VLCFA accumulation has an adverse effect on membrane structure and function. For example, in cultured adrenocortical cells, the addition of C26 0 to the media results in increased microviscosity of the cell membrane and decreased secretion of cortisol after ACTH stimulation. Although similar studies have not been carried out in nerve cells, the effect of VLCFA on neural cell membranes may also result in the neurological manifestations of patients with X-ALD. 

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). 

I., Fernandez-Boya, B., De La Torre, M.P., Munoz-Yague, M.T. Reversal of carbon tetrachloride induced changes in microviscosity and lipid composition of liver plasma membrane by colchicine in rats. Gut 1993 34 1438-1442... 

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... 

Shinitzky, M., Dianoux, A.-C., Weber, G. Microviscosity and order in the hydrocarbon region of micelles and membranes determined with fluorescent probes. I. Synthetic micelles. Biochemistry 1971, 70(11), 2106-2113. 

A second approach with respect to anisotropic flavin (photo-)chemistry has been described by Trissl 18°) and Frehland and Trissl61). These authors anchored flavins in artificial lipid bilayers by means of C18-hydrocarbon chains at various positions of the chromophore. From fluorescence polarization analysis and model calculations they conclude, that the rotational relaxation time of the chromophore within the membrane is small compared to the fluorescence lifetime (about 2 ns74)). They further obtain the surprising result that the chromophore is localized within the water/lipid interface, with a tilt angle of about 30° (long axis of the chromophore against the normal of the membrane), irrespective of the position where the hydrocarbon chain is bound to the flavin nucleus. They estimate an upper limit of the microviscosity of the membrane of 1 Poise. 

We should first emphasize that viscosity is a macroscopic parameter which loses its physical meaning on a molecular scale. Therefore, the term microviscosity should be used with caution, and the term fluidity can be alternatively used to characterize, in a very general way, the effects of viscous drag and cohesion of the probed microenvironment (polymers, micelles, gels, lipid bilayers of vesicles or biological membranes, etc.). 

Vesicle size, bilayer fluidity, membrane permeability, microviscosity, ability to bind small molecules, suseeptibility to pore formation, flip-flop rates, extent of water penetration, lateral amphiphile diffusion, vesiele fusion, and kinetic medium effeets (some of which will be discussed briefly below) all depend on the paeking of... 

Some studies have shown increased risks of violent death and depression in subjects with reduced serum cholesterol concentrations. Serum and membrane cholesterol concentrations, the microviscosity of erythrocyte membranes, and platelet serotonin uptake have been determined in 17 patients with hypercholesterolemia (21). There was a significant increase in serotonin transporter activity only during the first month of simvastatin therapy. This suggests that within this period some patients could be vulnerable to depression, violence, or suicide. This is an important paper, in that it explains why mood disorders are not regularly seen in clinical trials with statins, as has been summarized in a recent review (3). 

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