[Effect of cholinergic substances on the spontaneous activity of lower respiratory tract neurons]

Acetylcholine and low concentrations of nicotine were shown to increase firing rate, to induce grouping of spikes of spontaneously active cells and to activate "silent" neurons. High concentrations of nicotine exert a biphasic (excitatory-inhibitory) effect. Atropine just alters and benzohexonium suppresses the spontaneous unit activity. Changes in the unit activity seem to stem from an interaction of cholinergic substances with the nicotine and muscarine cholinoreceptors. Neurons with a mixed type activity were found to receive inhibitory cholinergic projections.