Dual nature of the peaks of light scattered during spreading depression in chick retina.

In this work some physical properties of the optical concomitants of spreading depression (SD) are investigated in isolated chick retinas. The two peaks of light scattering during the phenomenon were studied at various wavelengths of the illuminating light. It was shown that the first fast increase in light scattering is highly dependent on the wavelength and seems to be a "blue" scattering. The second slow peak, not so dependent, behaves as a "white" scattering. This implies in different underlying physical mechanisms for the two peaks. Based in this dissimilar behavior, using appropriate optical device and adding some substances to the maintaining Ringer solution it could be observed that the death of tissue is accompanied by a light scattering change comparable to the first peak of SD. The opalescence of the second peak is more similar to the opalescence caused by addition of NaCl to the Ringer in which the fragment of retina is maintained.