Modulation of Ciliary Beat Frequency in the Upper Airway by Prostaglandins

Prostaglandins are ubiquitous within tissues and participate in several local regulatory functions. Previous reports have presented conflicting evidence on their role in ciliary activity in the upper airway. We studied the in vitro effects of prostaglandin E₂ (PGE₂) and a prostaglandin I₂ analog (Iloprost) on the ciliary beat frequency (CBF) of human adenoid explants and rabbit sinus mucosa. Tissue explants were maintained in culture at 35°C. PGE₂ or Iloprost was added to the culture media at concentrations of 10^–6, to 10^–12 M. CBF was determined using phase contrast microscopy and microphotometry. PGE₂ increased CBF with a maximum increase of 54.6% in rabbit mucosa (P < 0.01) and 20.0% in human adenoid (P < 0.009). Iloprost increased CBF with a maximum increase of 35.2% in rabbit mucosa (P < 0.02) and 16.4% in human adenoid (P < 0.03). Induced production of endogenous prostaglandins was determined by treating specimens with a cyclooxygenase inhibitor (diclofenac) prior to addition of PGE₂ or Iloprost. Diclofenac had no effect on the ciliostimulatory effects of PGE₂ (P > 0.36), however it significantly decreased the ciliostimulatory effect of Iloprost (P < 0.037). Both PGE₂ and Iloprost stimulate ciliary motility, yet the action of PGE₂ is direct, whereas Iloprost stimulates cilia by release of endogenous prostaglandins in both the human and rabbit.