X-ray scattering study of pike olfactory nerve: elastic, thermodynamic and physiological properties of the axonal membrane.

The effects of several agents, sugars, isotonic KCl, and a variety of drugs, on the structure of the axonal membranes of unmyelinated pike olfactory nerve have been studied by synchrotron radiation X-ray scattering experiments. The main effects of the sugars are: (i) to increase the electron density of the extra-axonal space and thereby yield the absolute scale of the electron density profile; (ii) to osmotically stress the membrane and thus yield its elastic modulus of area compressibility, since the related strain, thickness dilation, is directly determined by the X-ray scattering experiments. Exposure to isotonic KCl, a depolarizing agent, induces membrane thickness to increase.

X-ray scattering study of pike olfactory nerve: intensity of the axonal membrane, solution of the phase problem and electron density profile.

Synchrotron radiation X-ray scattering experiments were performed on unmyelinated pike olfactory nerves. The difference between the meridional and the equatorial traces of the 2-D spectra yielded the 1-D equatorial intensity of the macromolecular components oriented with respect to the nerve: axonal membranes, microtubules and other cytoskeletal filaments. These 1-D spectra display a diffuse band typical of bilayer membranes and, at small s, a few sharper bands reminiscent of microtubules.