Neuromuscular blocking agents predominantly block muscle type nicotinic acetylcholine receptors as opposed to the neuronal type. However, there is growing evidence that neuromuscular blocking agents have affinity to some neuronal nicotinic acetylcholine receptors. The carotid body chemoreceptor as the essential oxygen-sensing cell, relies on cholinergic signalling. Atracurium and vecuronium impair carotid body chemoreceptor activity during hypoxia. Here, we characterize atracurium and vecuronium as antagonists at nicotinic receptors of the carotid body chemoreceptor. Isolated rabbit carotid body preparations with carotid sinus nerve were used, and chemoreceptor activities were recorded. There was a concentration-dependent reduction in the chemoreceptor responses to nicotine, with an IC50 to 50 µg nicotine of 3.64 and 1.64 µM and to 500 µg nicotine of 27.00 µM and 7.29 µM for atracurium and vecuronium, respectively. It is concluded that atracurium and vecuronium depress nicotine-induced chemoreceptor responses of the carotid body in a dose-dependent fashion. © 2004 Elsevier B.V. All rights reserved.