Electrical field stimulation of isolated guinea pig lung parenchyma strips: a method to study peripheral bronchi and peripheral blood vessels.

The reaction of isolated guinea pig lung parenchyma strips to electrical field stimulation (EFS) has been characterized in vitro. Lung parenchyma strips reacted to EFS with a frequency-dependent initial twitch followed by a long-lasting contraction. The initial fast contraction was abolished by tetrodotoxin, whereas the tonic contraction was not influenced by this substance. The initial twitch was reduced but not abolished by atropine as well as by phentolamine. It was concluded that the reaction of guinea pig lung parenchyma strips to EFS consists of a cholinergic and an adrenergic component representing probably the responses of small bronchi and small blood vessels, respectively. The nature of the nonadrenergic-noncholinergic component of the initial twitch as well as of the nature of the nonneural tonic contraction are still unclear.