Published ahead of print on February 16, 2006, doi:10.1165/rcmb.2005-0417OC
© 2006 American Thoracic Society DOI: 10.1165/rcmb.2005-0417OC Ciliary Beat Frequency Is Maintained at a Maximal Rate in the Small Airways of Mouse Lung SlicesDepartment of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts Correspondence and requests for reprints should be addressed to Dr. Michael J. Sanderson, Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue, North Worcester, MA 01655. E-mail: michael.sanderson{at}umassmed.edu
Ciliary beat frequency (CBF) is a key factor in the defense of the airways, and ATP can stimulate CBF by increasing intracellular calcium concentration ([Ca2+]i). However, the regulatory effects of ATP have been mainly studied in cultured or isolated epithelial cells from the large cartilaginous airways. The aim of this study was to evaluate the regulation of CBF in small airways of lung slices that are representative of in vivo tissue. Mice lungs were inflated with agarose and cut into thin slices with a vibratome. CBF in the small bronchioles was observed with differential interference contrast microscopy and quantified using high-speed digital imaging (at 240 images s–1). We found that the in situ organization of the ciliated cells was well preserved and that their CBF was high. We verified the fidelity of our recording system by analyzing rapid changes in CBF in response to temperature. However, we found that ATP had no effect on CBF, despite the fact that the [Ca2+]i, measured with confocal fluorescence imaging, was increased. Ionomycin and purinergic or
Key Words: ATP • Ca2+ • high-speed digital microscopy • small airways This article has been cited by other articles:
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-adrenergic agonists also failed to increase CBF. Similar results were obtained in outgrowths of cells cultured from lung slices. By contrast, ATP increased the slower CBF of outgrowths of ciliated cells cultured from tracheal rings. Therefore, we conclude that CBF in intrapulmonary airways of mice is maintained at a maximum rate and cannot be further increased by agonist stimulation. These conditions would ensure that mucociliary clearance is constantly active to provide continuous airway protection. 
