Dopamine Efflux from the Carotid Body During Hypoxic Stimulation

Abstract

The carotid bodies of cats are known to contain high levels of dopamine (DA), persisting even after complete denervation of these organs (Zapata et al, 1969; Mir et al, 1982; Fitzgerald et al, 1983). Thus DA appears to be concentrated in glomus cells, characterized by their chromaffin reaction, abundance in dense-core granules and formaldehydeinduced fluorescence (see Eyzaguirre & Zapata, 1984). Since the DA content and the number of dense-core granules are reduced in direct proportion to the severity and duration of hypoxia in rats (Hanbauer & Hellström, 1978; Hansen, 1981), and radiolabeled DA effluxes from rabbit and cat carotid bodies —in parallel with the frequency of carotid chemosensory discharges (f _x)— are also proportional to the intensity of hypoxic superfusions (Fidone et al, 1982; Rigual et al, 1986), the idea that DA serves as the glomus cell to sensory nerve endings transmitter during hypoxia is highly attractive (see Gonzalez et al, 1994).