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Updated: Aug 30, 2026

Utilizing the Precision-Cut Lung Slice to Study the Contractile Regulation of Airway and Intrapulmonary Arterial Smooth Muscle
Published on: May 5, 2022
Force and myosin light chain phosphorylation in dog airway smooth muscle activated in different ways
Theodor Burdyga1, Richard W Mitchell, Joseph Ragozzino
1Department of Medicine, Krannert Institute of Cardiology, Indiana University, 1800 North Capitol Avenue, Indianapolis, IN 46202, USA. burdyga@liverpool.ac.uk
Abstract:
To assess activation mechanisms of dog trachealis muscle and test whether isometric force generation could be separated from myosin light-chain (MLC) phosphorylation, force and phosphorylation were measured in the presence of wortmannin (a light-chain kinase inhibitor) or Y-27632 (a rho-kinase inhibitor) during electrically stimulated tetani and sustained contractures induced by acetylcholine, KCl, or calyculin A, a light-chain phosphatase inhibitor which caused irreversible contractures and both di- and mono-phosphorylation of light chain. Phosphorylation was not much more than half under any circumstances. A nearly constant proportionality between steady force and phosphorylation existed over a 9-fold force range during contractures and 25-sec tetani, except that force correlated best with the di-phosphorylated light chain produced by calyculin A. Phosphorylation was disproportionately higher than force at the outset of tetani, and this disproportion was exaggerated by Y-27632. The results suggest that about half the light chain is sequestered from kinases and that mechanical activation is tightly linked to phosphorylation, except at the outset of stimulation.
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