Stimulation of ciliary beat frequency by autonomic agonists: in vivo

Abstract

beta 2-Adrenergic bronchodilator and muscarinic cholinergic bronchoconstrictor agonists both stimulate ciliary activity in vitro. To test the hypothesis that increases in autonomic activity would result in increases in ciliary beat frequency (CBF) in vivo, a correlation analysis heterodyne laser light-scattering system was developed and validated to measure the stimulating effects of sympathomimetic and parasympathomimetic agonists on tracheal CBF in intact, anesthetized beagles. The mean baseline CBF from 42 studies of 274 measurements in 9 (5 male and 4 female) adult beagles was 6.6 +/- 1.1 Hz. The stimulating effects of a beta 2-adrenergic agonist, fenoterol, and a muscarinic cholinergic agonist, methacholine, on CBF were studied on four and eight beagles, respectively. The studies were randomized and blinded. Aerosolized 10(-5) M fenoterol stimulated the CBF from the base line of 6.8 +/- 2.5 to 32.0 +/- 17.9 Hz in four dogs. Aerosolized methacholine stimulated the CBF from the base line of 5.8 +/- 0.7 to 9.4 +/- 3.0 Hz for 10(-8) M, and to 12.6 +/- 3.1 Hz for 10(-6) M in eight dogs. These are the first data obtained in intact animals that demonstrate CBF in the lower respiratory tract is regulated by autonomic agonists.

Mucociliary transport in porcine trachea: differential effects of inhibiting chloride and bicarbonate secretion

“…Ciliary beat frequency (CBF) in mammalian airways is variable, but typically ranges between 5 and 15 Hz (23,34,46,47). When muscarinic agonists are applied to airway epithelia, CBF increases approximately twofold (46,47); however, this effect is transient, with CBF returning to near baseline levels within 20 -30 min (46). Furosemide, which like bumetanide inhibits NKCC and transepithelial Cl Ϫ secretion, has no appreciable effect on tracheal CBF when administered in vivo to dogs or baboons (45) or in vitro to rabbits (40).…”

Effects of albuterol enantiomers on ciliary beat frequency in ovine tracheal epithelial cells

“…Thus higher concentrations of agonist may be necessary to stimulate a sufficient number of receptors to elicit a physiological response. In fact, relatively high EC 50 values have been reported for isoproterenol (EC 50 ϳ5 M) in rabbit tracheal explants (27,33) and for fenoterol (EC 50 ϳ10 M) in beagle trachea in vivo (35). Clinically, the necessity for such high doses is not an issue because millimolar concentrations of albuterol are potentially encountered by ciliated cells after nebulization of the drug into the airways (the concentration of nebulized ␤ 2 -agonists is Ͼ1 mM).…”

Impact of Genetic Diagnosis on Clinical Management of Patients With Congenital Heart Disease

“…It may be beneficial for CHD-PCD patients to have intensive regular chest physiotherapy, even while they appear clinically well. There is some evidence that beta-agonists increase ciliary beat frequency 18 , and therefore may be beneficial in those CHD-PCD patients with slowed ciliary beat. Finally, in contrast to care of CHD, aggressive antibiotic management of pulmonary symptoms is a cornerstone of PCD care 17 .…”