Co-Cultures of Rat Petrosal Neurons and Carotid Body Type 1 Cells

In mammals reflex hyperventilation following acute hypoxia is mediated via impulses in the carotid sinus nerve (CSN) which supplies afferent innervation to O2- sensitive type 1 cells of the carotid body (Eyzaguirre & Zapata, 1984; Gonzalez et al, 1994). Type 1 cells contain multiple neurotransmitters, several of which are potential candidates for initiating or modulating CSN discharge during chemosensory signaling. The underlying synaptic events are poorly understood, and even controversial, in part because it is difficult to obtain reliable recordings from the afferent nerve endings in situ (see Eyzaguirre et al, 1983), and the transmitter sensitivity of these endings or of their parent cell bodies are unknown. Here we describe a preparation based on co-culture of rat type 1 cells and their afferent (petrosal) neurons which, combined with electrophysiological perforatedpatch recording from identified neurons, provide an attractive approach for studying these mechanisms. Previous attempts using co-cultures of rat type 1 cells and nodose (sensory) neurons were hampered by the paucity of successful contacts, probably due to the low frequency of ‘appropriate’ chemosensory neurons present (Alcayaga & Eyzaguirre, 1990).