Distribution of kainic acid receptor binding sites in the goldfish CNS: evidence for the existence of intracellular sites.

The density of binding sites for kainic acid was measured both in fresh slices and in the particulate fraction of the homogenate from various zones of the CNS of goldfish. Binding in the homogenate fraction was always found higher than in the corresponding slices, which should be representative of receptors located on the outer surface of the cellular membrane. The hypothesis is discussed that the sites demonstrated by homogenization are located in the intracellular compartment.