The effects of anticholinesterases on the bronchioles and pulmonary blood vessels in isolated perfused lungs of the dog.

The effects of two potent inhibitors of cholinesterase, isopropylmethylphosphonofluoridate (sarin) and ethyl pyrophosphate (TEPP), were investigated on the bronchioles and pulmonary blood vessels in isolated dog lung preparations perfused with heparinized blood and ventilated artificially. These anticholinesterases caused gradual bronchoconstriction as indicated by a diminution in tidal air volume, a reduction in compliance and an increase in expiratory resistance. These effects were antagonized by atropine. An increase in pulmonary vascular resistance occurred which was enhanced by the addition of small quantities of acetylcholine to the perfusing blood. The pulmonary vascular effects of acetylcholine, sarin and TEPP were prevented and abolished by atropine. Evidence is presented which suggests that the site of action of these anticholinesterases is, at least in part, peripheral to the autonomic ganglia.