Localization of [3H]glutamate binding sites in rat adrenal medulla.

A significant activity of L-[3H]glutamic acid binding was detected in the membranous particulate preparations obtained from the rat adrenal glands. In vitro addition of sodium acetate (100 mM) resulted in a drastic enhancement of the binding to cerebral preparations, while inducing a significant inhibition of the adrenal binding. Quisqualic acid elicited a prominent suppression of the adrenal binding in a concentration-dependent manner to a slightly greater extent than the inhibition of cerebral binding. N-Methyl-D-aspartic acid exerted a significant stimulatory action on the adrenal binding without affecting the cerebral binding. The adrenal medullary part possessed more than 5-fold higher binding activity than that in cortical part. These results suggest the possible existence of [3H]glutamate binding sites in rat adrenal glands which are distinctly different from those in the central structures.