[Effects of K+-depolarization on the physical state of membrane lipids in brain synaptosomes of the rat].
The microstructure of lipid bilayer in synaptosomes from rat brain upon K+-depolarization (30 mM) was studied using the inductive resonance energy transfer (IRET) from proteins to the fluorescent probes, pyrene and DMC (4-dimethylaminochalcone). The effectiveness of IRET was not changed by the K+-depolarization. The monomer-to-eximer ration (Fm285/Fe285) of pyrene fluorescence intensities in IRET was 1.5 times lower upon depolarization than in controls. This suggested a decreased microviscosity of the lipid bilayer in immediate environment to proteins of the synaptosomal membrane. The Fm338/Fee338 ratio as well as polarization of DMC fluorescence indicative of the bulk lipid phase were not altered under these conditions. Neither cytochalasin B not colchicine had any effect on fluorescence polarization of DMC both in control and depolarized synaptosomes. It is suggested that the increased lateral mobility of protein-associated lipid molecules found in depolarized synaptosomes may be caused by alterations in the activity of ion channels and ion pumps or by restructuring of the cytoskeletal network.
Timofeev
A A
AA
Glebov
R N
RN
D000818:Animals; D001921:Brain / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D005454:Fluorescence Polarization; D008563:Membrane Lipids / Q000032:analysis* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D013574:Synaptosomes / Q000032:analysis* / Q000378:metabolism
D008563:Membrane Lipids; D011188:Potassium
Vliianie K+-depoliarizatsii na fizicheskoe sostoianie membrannykh lipidov v sinaptosomakh mozga krys.