Abstract
To elucidate whether macrolide antibiotics affect cholinergic neuro-effctor transmission in the airway, we studied canine isolated bronchial segments under isometric conditions in vitro. Addition of erythromycin (3×10^<-4>M) attenuated the contractile responses to electrical field stimulation (EFS), so that the stimulus frequency required to produce a half-maximal contraction (ES_50) increased from 1.3±0.3 to 5.1±0.5Hz (P<0.001). This effect was concentration-dependent and not influenced by propranolol, indomethacin, ouabain or mechanical removal of the epithelium. In contrast, contractile responses to acetylcholine were not altered by erth-romycin. These results suggest that erythromycin may inhibit neuro-effector transmission in the airway cholinergic motor pathway, probably involving the reduction of exocytotic release of acetylcholine from the nerve terminals.
