Electrophysiological properties of a new isolated rat retina preparation.

A piece of rat retina was mounted in an open chamber and perfused with a Ringer solution at 37 degrees C. The electroretinogram (ERG) was recorded between an extracellular microelectrode in contact with the rod outer segments and a reference electrode under the retina. The addition of 250-500 microM of glutamate to the media prevented the b-wave from decaying in amplitude with time. Minor components of the ERG, the scotopic threshold response (STR) and oscillatory potentials (OPs), were well maintained with glutamate in the media. Experiments on the spatial properties of the recordings indicated that a small area immediately around the microelectrode contributes most strongly to the response. The similarity of ERGs recorded in vivo from the cornea to the transretinal ERGs from the isolated retina of the same animal indicated that the functional integrity of the isolated retina was well preserved in the media with glutamate.