Ciliary beat frequency desensitization in an ovine alcohol exposure model

Abstract

Mucociliary clearance is regulated in part by changes in the ciliary beat frequency (CBF) of epithelial cells lining the airways. We have demonstrated that exposure to human intoxicating concentrations of ethanol (100 mM) can result in chronic desensitization of CBF in response to beta agonists in both rat and mouse models of alcohol exposure. We hypothesized that maternal exposure to alcohol in an ovine model would result in desensitized CBF in newborn lambs. Ewes were exposed to 1mg ethanol/kg body weight of 40% ethanol solution during the last 5 weeks of pregnancy by cannulation in the last ruminant stomach. Ewes from a second set were transdermally exposed to 21 mg nicotine for the same time. At full-term parturition, lambs were sacrificed and trachea necropsied. CBF was assayed ex vivo using digital whole-field analysis of tracheal ring cilia in the presence or absence of 100 μM isoproterenol (ISO) for 30 m. The remainder of the tracheal epithelium was extracted for direct assay of cAMP-dependent protein kinase (PKA). Baseline CBF was approximately 6–7 Hz in control lamb trachea. ISO stimulated a 4–5 Hz increase in CBF from control or lambs maternally exposed to nicotine. Conversely, maternal alcohol-exposed lambs showed no response to ISO. Likewise, epithelial cell PKA activity was elevated twofold in response to ISO, but not in maternal alcohol-exposed lamb trachea. These data suggest that maternal alcohol exposure can cause cilia dysfunction in the newborn, potentially impacting early host lung defense. Supported by VA Merit, NIH-AA08769, and ALA grants