STIMULATION OF TRACHEAL CILIARY BEAT FREQUENCY BY LOCALIZED TISSUE INCISION

Since measurements of basal ciliary beat frequency (CBF) were significantly lower in our intact canine experiments than reports of ciliary activity in rabbits involving surgical intervention, we hypothesized that local tissue trauma stimulates CBF. The effects of minor neck surgery on trachea CBF in eight barbiturate-anesthetized eucapnically ventilated beagles were investigated. Each dog underwent two studies. Measurements of CBF were made at 1-min intervals of the right lateral miditracheal surface by means of dyne mode correlation analysis laser light scattering. In the control study, CBF was measured in each dog for at least 160 min. In the incision study, base-line CBF was measured for at least 40 min. The overlying sternohyoidus muscles were then separated, and a longitudinal 2- to 3-cm incision was made in the trachea caudally from the fourth to the fifth cartilage ring. CBF was measured at least 5 cm distally from the site of tracheal injury for an additional 120 min. Electrocardiogram, rectal temperature, tracheal pressure, exhaled CO2, and arterial blood pressure, PO2, PCO2, and pH remained stable throughout both studies. The mean base-line CBF was 4.7 ± 0.4 Hz. It increased to 19.5 ± 2.9 Hz (P < 0.0001) 100 min after the incision and remained elevated until the end of the study period (P < 0.0001). The mechanism(s) causing this stimulation may also be responsible for the high 'basal' CBF observed in other studies. Since the in vivo regulatory mechanisms for basal tracheal CBF differ from those responsible for the stimulatory response, these data indicate that a nontraumatized tissue preparation is critical in the evaluation of the mechanisms regulating CBF.