Electron-microscopic study of gamma-aminobutyric acid immunoreactivity in the chief cells of the mouse carotid body.

The present study shows gamma-aminobutyric acid (GABA) immunoreactivity in almost all chief cells of the mouse carotid body. GABA immunoreaction products were distributed diffusely in the cytoplasm as well as in the dense-cored granules. These findings suggest that GABA may be localized in the cytoplasm and granules, and may be released from the cells.