Cortisol effect on (Na+ + K+)-stimulated ATPase activity and on bilayer fluidity of dog brain synaptosomal plasma membranes.
The binding of [14C]cortisol into dog brain synaptosomal plasma membranes (SPM) follows an exponential path described by the general formula y = a.ebx. The specific activity of the SPM-bound (Na+ + K+)-stimulated ATPase was linearly increased at different concentrations of cortisol. Changes in the allosteric properties of (Na+ + K+)-stimulated ATPase by fluoride (F-) (i.e. changes of Hill coefficients) indicate that cortisol increases the membrane fluidity. The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labeled SPM decreased in cortisol treated SPM compared to untreated (control) SPM, which is consistent with a general increase in membrane fluidity. This increase of fluidity by cortisol may play a role in the physiological effects of this hormone in the brain.
D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry / Q000187:drug effects*; D004285:Dogs; D004789:Enzyme Activation; D005454:Fluorescence Polarization; D005459:Fluorides / Q000494:pharmacology; D006854:Hydrocortisone / Q000378:metabolism / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000187:drug effects; D008560:Membrane Fluidity / Q000187:drug effects*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism
D000254:Sodium-Potassium-Exchanging ATPase; D005459:Fluorides; D006854:Hydrocortisone