Erythrocytes, permeability

Other additional studies or pertinent information that lend support to this MRL An intermediate-duration gavage study in rats found decreased hematocrit and erythrocyte counts relative to before-treatment values (Galal et al. 1977), but this study had some limitations, including lack of a control group and disparities between text and tables. Another intermediate duration gavage study in male rats demonstrated dose-related significant decreases in mean corpuscular volume (Undeger et al. 2000). An effect on the erythrocyte is plausible because erythrocyte cholinesterase has a function in the control of erythrocyte permeability (Wills 1972). 

Ahnert-Hilger, G., Chhtwal, G.S., Hesslet, H.J., and Haberman, E. (1982) Changes in erythrocyte permeability due to palytoxin as compared to amphoterm B. Biochim. Biophys. Acta, 688, 486-494. 

Acetylcholinesterase contained in erythrocytes is identical to that found in the nervous system. Its function within erythrocytes may be to control permeability of the cell membrane, to an extent. 

Only a subset of the parameter values in the O Flaherfy model require inputs from the user to simulate blood and tissue lead concentrations. Lead-related parameters for which values can be entered into the model include fractional absorption from the gastrointestinal tract partition coefficients for lead in nonbone tissues and in the surface region of bone maximum capacity and half-saturation concentration for capacity-limited binding in the erythrocyte elimination clearance fractional clearance of lead from plasma into forming bone and the restricted permeability coefficients for lead diffusion within bone, from plasma into bone, and from bone into plasma (O Flaherty 1991a). 

Several mechanisms are involved in the permeability through Caco-2 cells. In order to obtain a more pure measure of membrane permeability, an experimental method based on ghost erythrocytes (red blood cells which have been emptied of their intracellular content) and diffusion constant measurements using nuclear magnetic resonance (NMR) has been proposed [108]. 

The importance of lipids in membrane structure was established early in the 20th century when pioneering biophysicists established positive correlations between cell membrane permeabilities to small non-electrolytes and the oil/water partition coefficients of these molecules. Contemporary measurements of the electrical impedance of cell suspensions suggested that cells are surrounded by a hydrocarbon barrier, which was first estimated to be about 3.3 nm thick. This was originally thought to be a lipid monolayer. Among the pioneering biophysical experiments were those that established that the ratio of the area of a monolayer formed from erythrocyte... 

It has been reported4 that cholinesterase inhibitors (such as di-isopropyl phosphorofluoridate) increase the permeability of squid giant axons towards sodium and potassium. There is also an indication that the erythrocyte requires, among other factors, an adequate acetylcholine-cholinesterase system to prevent a gain of sodium or a loss of potassium.5 The conclusion that permeability is dependent on cholinesterase activity, however, seems to be contested by Strickland and Thompson.6... 

Gryns (1896), Hedin (1897), and especially Overton (1900) looked at the permeability of a wide range of different compounds, particularly non-electrolytes, and showed that rates of penetration of solutes into erythrocytes increased with their lipid solubility. Overton correlated the rate of penetration of the solute with its partition coefficient between water and olive oil, which he took as a model for membrane composition. Some water-soluble molecules, particularly urea, entered erythrocytes faster than could be attributed to their lipid solubility—observations leading to the concept of pores, or discontinuities in the membrane which allowed water-soluble molecules to penetrate. The need to postulate the existence of pores offered the first hint of a mosaic structure for the membrane. Jacobs (1932) and Huber and Orskov (1933) put results from the early permeability studies onto a quantitative basis and concluded molecular size was a factor in the rate of solute translocation. 

In the majority of patients with sickle cell disease, anemia is not the major problem the anemia is generally well compensated even though such individuals have a chronically low hematocrit (20-30%), a low serum hemoglobin level (7-10 g/dL), and an elevated reticulocyte count. Instead, the primary problem is that deoxygenated HbS chains form polymeric structures that dramatically change erythrocyte shape, reduce deformability, and elicit membrane permeability changes that further promote hemoglobin polymerization. Abnormal erythrocytes... 

From c. 1900 experiments, many of them with mammalian erythrocytes, indicated cells were selectively permeable to a range of low molecular weight neutral solutes. If molecules with similar structures were added to the suspension medium, entry of the test solute might be reduced. 

Sukul NC, De A, Sinhababu SP, Sukul A. 2003. Potentized Mercuric chloride and Nux vomica facilitate water permeability in erythrocytes of a freshwater catfish Clarius batrachus under acute ethanol intoxication. J Alt Comp Med 9 719-725. 

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