Endothelin-3 increases transmission in the rabbit pulmonary parasympathetic nervous system

The effect of endothelin-3 (ET-3) on the response to parasympathetic nerve stimulation of rabbit isolated bronchus was examined. The site of action of ET-3 in the pulmonary parasympathetic nervous system was also investigated. ET-3 induced a concentration-dependent increase in the response to electrical field stimulation. The response was atropine sensitive and therefore cholinergically mediated. At a concentration of 10 nM, ET-3 increased the response to field stimulation to 205 +/- 42% of the initial response. The effect was concentration-related, as 100 nM further increased this response to 315 +/- 69%. The responsiveness of the tissue to exogenous acetylcholine was not affected by ET-3. Therefore ET-3 has a neuromodulatory role on cholinergic parasympathetic transmission in rabbit airways exerted at a prejunctional site.