Characterization of nicotinic acetylcholine receptors in cultured arterial chemoreceptor cells of the cat.

Neurotransmitters appear to be involved in chemotransmission of the carotid body, a major arterial chemoreceptor. Substantial data indicate that acetylcholine (ACh) is an excitatory neurotransmitter in the carotid body, regulating the excitability of afferent nerve endings and glomus cells (putative chemoreceptor cells). In this study we characterized properties of nicotinic ACh receptors (nAChRs) in cultured cat glomus cells using immunocytochemistry and whole cell patch clamp techniques. Cultured glomus cells expressed immunoreactivity for alpha3, alpha4, and beta2 subunits of nAChRs. An application of ACh elicited inward current. Nicotinic AChRs of glomus cells showed high affinity for ACh. The current-voltage relationship showed strong inward rectification at positive membrane potential. alpha-Conotoxin MII (20 nM), dihydro-beta-erythroidine (DHbetaE; 1 nM), and hexamethonium (300 microM) significantly inhibited ACh-induced current. These results indicate that cultured cat glomus cells possess functional nAChRs, and that their characteristics are consistent with those of alpha3, alpha4 and beta2 containing nAChRs.