Figure 9. Immunofluorescence staining GABA in cultured cells and of GABA_AR β subunit in tissue sections of whole rat carotid body.

A, a type 1 cell cluster from a carotid body culture showed positive GABA-immunoreactivity. B–D, the same section of rat carotid body was immunostained with a polyclonal antibody against tyrosine hydroxylase (TH; red fluorescence) and a monoclonal antibody (bd17) against the β subunit of the GABA_AR (green fluorescence). Note positive TH- and bd17-immunofluorescence in type I cells (B) and nerve endings (C), respectively. In D (merge), the bd17-positive nerve endings are closely apposed to TH-positive type 1 cells, suggesting that in situ type 1 cells are contacted by afferent terminals expressing postsynaptic GABA_ARs. Scale bar = 10 μm in A and 20 μm in B–D.