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membrane structural characteristics. Erythrolysis and MDA content exhibited lipids
peroxidation (LPO) level. Membranes microviscosity was measured by electron spin
resonance of 2,2,6,6-tetramethyl-4-capryloyl-oxypiperidine-1-oxyl (lipidic label) and
5,6-Benzo-2,2,6,6-tetramethyl-1,2,3,4-tetrahydro-Ȗ-carbolyn-3-oxide (proteinic la-
bel). Phasic changes were found in the structural characteristics of the erythrocyte
membranes of mice involved in AD-like pathology. Those changes correlate with the
stages of the forebrain membrane À uidity alterations. Liability of the erythrocyte and
synaptosomal membranes are changing in opposite way for Sham operated (ShO)
mice. Thus, structural state of the erythrocyte membranes can be used as measure of
the forebrain membrane structural state. The obtained results testify failures in the
system of LPO regulation.
5.2 EXPERIMENTAL
The samples of bulbectomized (BE) and ShO mice (NMRI strain, females) were kind-
ly given to us by N. V. Bobkova (Institute of Cell Biophysics RAS). Every sample
contained joint blood of 4-5 mice. Erythrocytes were isolated from blood by means of
differential centrifugation at 1,000 g for 10 min. Membrane fluidity in two regions of
lipid bilayer was estimated with the help of ESR technique. The 2,2,6,6-tetramethyl-
4-capryloyl-oxypiperidin-1-oxyl (probe I) and 5,6-benzo-2,2,6,6-tetramethyl-1,2,3,4-
tetrahydro-Ȗ-carboline-3-oxyl (probe II) were used as a probes. Probes spin correlation
time was calculated from obtained spectra [2, 3], which correspond to the period of
radical's reorientation about ʌ/2. A probe spin correlation time is proportional to the
membrane microviscosity or inversely proportional to fluidity. It is known that probe
II localizes mostly in near-protein areas, probe I in protein-free areas of lipid bilayer
surface (2-4 ǖ) [4], thus the probes spin correlation time can show lipid-protein inter-
actions in membranes. In addition, erythrocytes lysis, and MDA content changes were
determined as a LPO rate index.
FIGURE 1
The probes spin correlation time in the erythrocyte membranes, (a) ShO mice and
(b) BE mice.
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