Antidromic nerve stimulation accelerates mucociliary activity in rabbit maxillary sinus.

The neuropeptide substance P (SP) is released from unmyelinated C-fibres in sensory nerves by antidromic nerve stimulation. In order to study the effect on mucociliary (m.c.) activity, the isolated distal end of the maxillary nerve was stimulated electrically (8 V, pulse rate 10 Hz, 5 ms pulses) 2-4 min, while the m.c. wave frequency in the maxillary sinus was recorded by a photoelectric technique. The m.c. wave frequency increased during stimulation by 35.4 +/- 4.9% (range 22.0-62.2%). Following pretreatment with atropine the m.c. activity increased by only 20.0 +/- 1.3% (range 14.9-21.9%) indicating that part of the response was mediated via stimulation of muscarinic receptors. The cholinergic part of the response is presumably secondary to release of SP since the SP antagonist [D-Pro2, D-Trp7,9]SP abolished the effect of nerve stimulation. Sympathetic ganglionectomy did not influence the response to antidromic nerve stimulation. It is concluded that antidromic stimulation of the maxillary nerve accelerates m.c. activity through a dual mechanism, involving release of SP, or SP-like peptides, from sensory C-fibre nerve endings as well as release of acetylcholine.