Modulating effects of antiasthmatic and antitussive drugs on autonomic neurotransmission in guinea-pig bronchial muscle in vitro.

Electrical field stimulation evoked a biphasic contraction of the guinea-pig isolated bronchi, consisting of a cholinergically mediated fast contraction followed by a non-cholinergically mediated slow contraction. Catecholamines, beta 2-stimulants, methylxanthines, antiallergic drugs, narcotic and non-narcotic antitussive drugs inhibited the neurogenic contractions not only by postjunctional depression of the response but also by prejunctional reduction of the transmitter release.