Effect of isoproterenol on the regulation of rabbit airway ciliary beat frequency measured with high-speed digital and fluorescence microscopy.
To investigate how isoproterenol, a beta-adrenergic agonist, regulates airway ciliary beat frequency (CBF), we simultaneously quantified changes in rabbit airway CBF and intracellular calcium concentration ([Ca2+]i) in response to isoproterenol (100 micromol/L) by using high-speed (240 frames per second) and fluorescence microscopy. At approximately 30 degrees C, isoproterenol induced a change in CBF that could be separated into two parts. First, isoproterenol induced a moderate increase in the basal CBF that was calcium-independent. This response was unaffected by buffering the [Ca2+]i with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrapotassium salt (BAPTA). Second, isoproterenol induced a transient increase in CBF that was superimposed on the increased basal CBF and correlated with a simultaneous transient increase in [Ca2+]i. This transient increase in CBF was abolished by BAPTA. We conclude that isoproterenol initially increases CBF through a calcium-independent mechanism, probably via protein kinase A, and subsequently through a calcium-dependent mechanism mediated by an increase in [Ca2+]i.
Zhang
Luo
L
Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
Han
Demin
D
Sanderson
Michael J
MJ
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D018929:Cell Culture Techniques; D002923:Cilia / Q000187:drug effects* / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology*; D008853:Microscopy; D008856:Microscopy, Fluorescence; D011817:Rabbits; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism; D014132:Trachea
D000318:Adrenergic beta-Agonists; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol; D002118:Calcium