Chronic ethanol downregulates PKA activation and ciliary beating in bovine bronchial epithelial cells.
Previously, we reported that ethanol (EtOH) stimulates a rapid increase in ciliary beat frequency (CBF) of bovine bronchial epithelial cells (BBEC). Agents activating cAMP-dependent protein kinase (PKA) also stimulate CBF. EtOH stimulates BBEC CBF through cyclic nucleotide kinase activation. However, EtOH-stimulated CBF is maximal by 1 h and subsides by 6 h, returning to baseline by 24 h. We hypothesized that the loss of EtOH-stimulated CBF was a result of downregulation of PKA activity. To determine the PKA activation state in response to EtOH, ciliated BBEC were stimulated for 0--72 h with various concentrations of EtOH and assayed for PKA. EtOH (100 mM) treatment of the cells for 1 h increased PKA activity threefold over unstimulated controls. PKA activity decreased with increasing time from 6 to 24 h. When BBEC were preincubated with 100 mM EtOH for 24 h, the stimulation of PKA by isoproterenol or 8-bromo-cAMP was abrogated. EtOH desensitizes BBEC to PKA-activating agents, suggesting that EtOH rapidly stimulates, whereas long-term EtOH downregulates, CBF via PKA in BBEC.
Wyatt
T A
TA
Research Service, Department of Veterans Affairs Medical Center, Omaha, Nebraska 68105, USA. twyatt@unmc.edu
Sisson
J H
JH
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000187:drug effects* / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D002923:Cilia / Q000187:drug effects / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D015536:Down-Regulation; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology; D000431:Ethanol / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D013997:Time Factors
D000318:Adrenergic beta-Agonists; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000431:Ethanol; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol