High density of specific GABA binding sites in the human fallopian tube.

The concentration of gamma-aminobutyric acid (GABA) in the human Fallopian tube and the ability of a membrane preparation from the same organ to bind [3H]GABA specifically were examined. A GABA concentration of 177 nM/g frozen tissue was determined and a single population of high-affinity receptor binding sites has been identified in the human oviduct. The density of binding sites demonstrated was as high as in the brain. These results indicate a physiological significance of GABA in the human Fallopian tube.