REGULATION OF CILIARY BEAT FREQUENCY BY BOTH PKA AND PKG IN BOVINE AIRWAY EPITHELIAL-CELLS

Ciliary beating is required for the maintenance of lung mucociliary tr ansport. We investigated the role of cyclic nucleotide-dependent prote in kinases in stimulating ciliary beat frequency (CBF) in bovine bronc hial epithelial cells (BBECs), cAMP-dependent protein kinase (PKA) act ivity and cGMP-dependent protein kinase (PKG) activity were distinguis hed after DEAE-Sephacel chromatography of BBEC extracts, cAMP levels a nd PKA activity are increased in BBECs stimulated with 0.01-1 mM isopr oterenol, with a corresponding increase in CBF. cGMP levels and PKG ac tivity are increased in BBECs stimulated with 0.1-10 mu M sodium nitro prusside, with a corresponding increase in CBF. Direct protein kinase- activating analogs of cAMP and cGMP (dibutyryl cAMP and 8-bromo-cGMP, respectively) also activate their specific kinases and stimulate CBF. Preincubation of BBECs with inhibitors of PKA or PKG [KT-5720 or Rp-8- (p-chlorophenylthio)-guanosine 3',5'-cyclic monophosphothioate] result s in the inhibition of specific kinase activity as well as in the inhi bition of CBF. These studies suggest that the activation of either PKA . or PKG can lead to the stimulation of CBF in bovine airway epitheliu m.