The airway preganglionic parasympathetic motoneurons (APPMs) supply the essential excitatory drive to the postganglionic parasympathetic motoneurons, which predominate in the nervous control of the airway physiologically and play critical roles in the genesis of airway hyperreactivity.The APPMs express multiple subunits of nicotinic acetylcholine receptors (nAChR) however the influence of endogenous acetylcholine (ACh) or exogenous nicotine on these neurons is unknown.In this study, the APPMs were retrogradedly labeled from the extrathoracic trachea of newborn rats, the inspiratory-activated APPMs (I-APPMs) innervating the tracheobronchial smooth muscle were functionally identified in rhythmically firing medullary slices, and the effects of nicotine and endogenous ACh were examined using voltage patch-clamp.The results show that nicotine (10 μmol/L) and acetyl cholinesterase inhibitor neostigmine (10 μmol/L) significantly increased the frequency and amplitude of the tonic excitatory postsynaptic currents (EPSCs), and caused a tonic inward current.The nicotine-induced changes of the tonic EPSCs was prevented by dihydro-β-erythroidine (DHβE), an antagonist of α4β2 type ofnAChR, at 3 μmol/L that is selective for α4β2 type of nAChR.The nicotine-induced tonic inward current was attenuated DHβE (3 μmol/L), and was abolished by addition of methyllycaconitine (10 nmol/L), an antagonist of α7 type of nAChR.Nicotine also caused significant increases in the GABAergic and the glycinergic spontaneous inhibitory postsynaptic currents, in both the frequency and the amplitude, which were also prevented by DHβE (3 μmol/L).Nicotine had no effect on the miniature excitatory or inhibitory postsynaptic currents in the pre-existence of tetrodotoxin.These results demonstrated that nicotine caused a direct postsynaptic excitatory effect that was mediated by both α7 and α4β2 type of nAChR, and enhanced the excitatory and the inhibitory inputs via activation of α4β2 type ofnAchR in the Ⅰ-APPMs.