The effect of platelet activating factor (PAF) on mucociliary transport of the eustachian tube was investigated both
in vitro and
in vivo, in healthy guinea pigs and in healthy chinchillas. Normal ciliated epithelium was carefully obtained from the eustachian tube of guinea pigs and incubated with RPMI 1640 solution in tissue culture. The mucosal specimens were incubated with PAF at concentrations ranging from 10
-10M to 10
-6M, and ciliary activity was observed under an inverted microscope, recorded on video tapes and photoelectrically quantified on a video monitor. PAF inhibited dosedependently ciliary activity
in vitro. For
in vivo study, 1 mL each of 10-5M PAF, 10
-5M PGE
2, 10
-5M PAF & PGE
2 or the control solution (0.1% methanol/PBS) was directly injected into the tympanic bullae of anesthetized chinchillas with a 27-gauge syringe. The middle ear was examined by otomicroscopy, tympanometry and ABR in relation to time. There was a significant difference in the average peak pressure of tympanograms between PAF-treated and control animals. Furthermore, PGE
2 augmented the inhibitory effect of PAF on middle ear clearance although injection of PGE
2 showed no significant effects. The threshold average of ABRs in the PAF group was significantly elevated compared with the control, and PGE
2 also augmented the effect of PAF. These data suggest that PAF inhibits mucociliary transport of the eustachian tube from the middle ear, and that PGE
2 plays an important role in the augmentation of inflammatory disorders.
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