Premium
Alteration of Synaptosomal Plasma Membrane Cholesterol Content: Membrane Physical Properties and Cation Transport Proteins
Author(s) -
Shapiro H. K.,
Barchi R. L.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb00435.x
Subject(s) - microviscosity , chemistry , membrane , phospholipid , cholesterol , biophysics , liposome , fluorescence anisotropy , synaptosome , membrane fluidity , phosphatidylinositol , biochemistry , chromatography , biology , phosphorylation
The level of nerve membrane cholesterol was altered by in vitro incubation of rat brain synaptosomal plasma membrane with liposomes having varying cholesterol contents. The normal plasma membrane cholesterol/phospholipid ratio of 0.3–0.4 (mol/mol) could be decreased by about one‐half or increased more than 100%. Fluorescence polarization measurements were made using the probe 1,6‐diphenyl‐1,3,5‐hexatriene. At temperatures below 35°C, lowering membrane cholesterol led to increased apparent microviscosity, while raising cholesterol content produced little change. However, at 45°C a continuous direct relationship existed between experimental membrane cholesterol/phospholipid ratio (ranging from 0.18 to 0.73) and apparent microviscosity. Under standard liposome‐synaptosomal plasma membrane exchange conditions, 80% of the initial specific [ 3 H]saxitoxin binding activity to the voltage‐dependent sodium channel and at least 95% of the (Mg 2+ ,K + )‐ p ‐nitrophenylphosphatae activity were preserved. Our results indicate that neither the characteristics of toxin binding nor the kinetics of this enzyme activity is dependent upon membrane cholesterol content.