Effect of exogenous ATP and physical stimulation on ciliary function impaired by bacterial endotoxin

The effects of exogenous ATP and physical stimulation on ciliary beat depressed by lipopolysaccharide from Pseudomonas aeruginosa were studied in cell culture. Both the ciliary beat frequency (CBF) and the amplitude (CBA) of human respiratory cells in monolayer cell cultures were studied by using a differential interference microscope equipped with a high speed video. Both the ATP and the physiol stimulation stimulated temporarily the depressed CBF and CBA. In both groups the CBF and CBA increased in 1 min to the initial level and then gradually decreased to the level before the stimulation. The duration of the ATP stimulation on the CBF (10.1 +/- 1.8 min) and CBA (10.1 +/- 2.3 min) were significantly better than the duration of physical stimulation on CBF (8.0 +/- 1.8 min) and CBA (6.8 +/- 1.6 min). However, the areas under the CBF/CBA curves (from the beginning of stimulation until the initial level of CBF or CBA was reached again) did not differ significantly. After the removal of the bacterial toxin the CBF was restored to the initial level. In the present study the adenosine receptor antagonist could not prevent the ciliostimulative effect of exogenous ATP combined with the physical stimulation. Both exogenous ATP and physical stimulation have a clear but temporary stimulative effect on the ciliary beat depressed by bacterial toxin, ATP being slightly more effective. It seems that the effects of ATP are not mediated by adenosine receptors.