[Effect of cholesterol on membrane Na,K-activated adenosine triphosphatase].

: The membrane preparations of rat brain Na,K-ATP-ase with different amount of cholesterol were obtained by using high-cholesterol diet or cholesterol-oxidase treatment. The cholesterol/protein ratio varied from 0.034 to 0.252 (normal--0.152). An increase of this ratio removes the curvature on the Arrhanius' plots for Na,K-ATP-ase, and a decrease--enhances it. The change of the temperature dependence pattern on the enzyme activity correlates with that of the spectral parameter of spin-labelled and rostane analogue, characterizing fluidity of membrane lipids in the same preparations. The authors conclude that the cholesterol level in the brain membranes monitors the activity of the membrane Na,K-ATP-ase.