The time required for mucociliary clearance from the nasal turbinate and the maxillary sinus was investigated in the same individual chickens using a specially designed plastic holder to monitor mucociliary clearance rates by direct vision through the palatine cleft. Determined in this way were: 1) the effect of SO
2 exposure during 16 hours per day for 7 consecutive days, 2) the effect of intranasal inoculation with the mesogenic strain of Newcastle disease virus (NDV), 3) the effect of mechanical stimulation of the palatine cleft by gentle touching with a dissecting needle, and 4) the effect of the nerve blocking drugs; atropine, scopolamine, reserpine and propranolol on the mechanical stimulation.
Intermittent exposure to 6ppm of SO
2 produced a turbinate time curve with double peaks of deceleration and intervening recovery periods, suggesting an intranasal mucociliary homeostatic response. In individual animals, 26 of 35 animals (75%) exposed to 6ppm, and 5 of 10 animals (50%) exposed to 20ppm showed the same patterns. Sinus clearance time in the chickens exposed to 20ppm of SO
2 returned to nearly normal after deceleration, suggesting also homeostatic mechanism.
NDV infection in chickens from a vaccinated flock induced little deceleration of intranasal clearance, while significant slowing was induced in chickens from an unvaccinated flock. This suggest that the severity of an intranasal infection may be measured by the rate of mucociliary clearance. Sinus clearance time in the NDV-infected chickens from an unvaccinated flock was accelerated between 2 to 5 days after infection in comparison with control levels, suggesting another type of mucociliary homeostasis due to NDV infection. In the chickens from a vaccinated flock, sinus clearance time was not affected by NDV infection.
Mechanical stimulation caused acceleration of mucociliary flow of the sinus: sinus clearance time was accelerated on the side adjacent to the mechanically stimulated side of the palatine cleft.
Mucociliary clearance in the chicken sinus was not affected by parasympatholytic agents, but was decelerated by the beta-adrenergic blocker. The effect of nerve blockers on the mechanical stimulation showed that parasympatholytic agents blocked the response induced by mechanical stimulation, while sympatholytic agents did not completely block the response. These data suggest that mucociliary clearance may be regulated by the reflex of the para- sympathetic and partially sympathetic nerve fibers.
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