[Spin probe study of the effect of cholera toxin on enterocyte brush border membranes]

The physical state of the enterocyte brush border membranes during stimulation of cholera diarrhea was examined by electron paramagnetic resonance with the use of spin probes localized in different areas of the lipid bilayer and the spin label covalently bound with protein SH-groups. In vivo experiments have disclosed a slight increase in bilayer fluidity during cholera intoxication. In experiments in vitro the binding of cholera toxin with the enterocyte brush border membranes on addition of 3',5'-AMP (up to 5 X 10(-5) M) did not affect the physical state of the lipid of protein areas of the membrane.