Cholinergic and C-Fibre Mediated Mechanisms in the Stimulation of Mucociliary Activity Induced by Prostaglandins and Histamine

Abstract

The involvement of cholinergic and C-fibre mediated mechanisms in the stimulation of mucociliary activity induced by prostaglandins and histamine was investigated in vivo in the rabbit maxillary sinus with a photoelectric technique. The prostaglandins E,(PGE,) and F2_2a (PGF_2a) in dose of 0.1 μg/kg and 10 μg/kg respectively stimulated the mucociliary activity in a biphasic fashion, with a small initial response during the first 1-2 min and a later maximum response after 3-4 min. These effects were resistant to atropine and to the SP antagonist (D-Pro², D-Trp^{7 9})SP. The small initial response was blocked by pretreatment with high doses of capsaicin (13 mg i.a.), while the maximum response was unaffected. This indicates that the mucociliary responses induced by PGE, and PGF^2a involve capsai-cin-sensitive C-fibres but that neither acetylcholine nor substance P were responsible.

Histamine (50 μg/kg) stimulated mucociliary activity in the rabbit maxillary sinus and the effect was abolished by pretreatment with high doses of capsaicin and reduced by the SP antagonist (D-Pro², D-Trp⁷')SP. This indicates that the histamine-induced stimulation of mucociliary activity involves capsaicin-sensitive C-fibres and that the effect might be mediated by substance P.

Key Words:

• prostaglandins
• histamine
• mucociliary activity.