Effect of cyclic AMP on ciliary activity of human respiratory epithelium

In order to investigate the effect of cyclic adenosine monophosphate (cAMP) on ciliary beat frequency (CBF) in human respiratory epithelium, cells were brushed from the inferior nasal turbinates of three groups of ten subjects: awake adults (aged 20-34 yrs), anaesthetized children (2-15 yrs) and anaesthetized adults (19-61 yrs). Cells from the awake adults were also studied after storage for 24 h in tissue culture medium. CBF was measured in vitro with a photometric technique at room temperature (22.0 +/- 1.5 degrees C). Samples were mounted in a perfusion chamber and challenged with either control solutions, dibutyryl cAMP (10(-4) or 10(-3) M), or the cyclic nucleotide-dependent protein kinase inhibitor 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine (H-7). Dibutyryl cAMP (10(-3) M) caused a significant increase in CBF in all groups studied: awake adults (+1.1 Hz; p less than 0.01), anaesthetized children (+1.2 Hz; p less than 0.01), anaesthetized adults (+1.2 Hz; p less than 0.01), stored cells (+1.1 Hz; p less than 0.01). This response was inhibited by preincubation with H-7 (10(-4) and 10(-3) M). It is concluded that cAMP is a regulator of ciliary activity in human respiratory epithelium.