Carotid Chemosensory Neurons in the Petrosal Ganglia are Excited by ACh and ATP
Several molecules have been proposed as excitatory transmitters between carotid body (CB) glomus (type I) cells and petrosal ganglion (PG) neurons (Eyzaguirre and Zapata, 1984; Gonzalez et al. 1994). Recently, experiments performed in the reconstituted rat CB chemosensory system (i.e. co-cultures of CB and petrosal-jugular cells) have suggested that both acetylcholine (ACh) and adenosine 5’-triphosphate (ATP) may act both as excitatory transmitters (Zhang et al. 2000). However, this experimental design cannot preclude that non-carotid chemosensory (gustatory) or other (i.e. mechanosensory) neurons present in the PG may establish contact with glomus cells. Moreover, the response of cultured nodose neurons to an acidic challenge (a CB natural stimulus) change when glomus cells are present in culture, suggesting that the changes arise from synaptic and/or trophic interactions between glomus cells and nodose neurons (Alcayaga and Eyzaguirre, 1991). To circumvent this difficulty, we studied the effects of both ACh and ATP on identified cat PG chemosensory neurons, using an in vitro preparation, in which the PG remains connected to the carotid bifurcation and CB (Belmonte and Gallego, 1983). In addition, we studied the electrophysiological responses induced by ATP and ACh in dissociated PG neurons using whole-cell patch clamp techniques.
KeywordsCarotid Body Carotid Sinus Excitatory Transmitter Glomus Cell Carotid Sinus Nerve
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