Mechanism of partial adaptation in airway smooth muscle after a step change in length
Open Access
- 1 August 2007
- journal article
- Published by American Physiological Society in Journal of Applied Physiology
- Vol. 103 (2), 569-577
- https://doi.org/10.1152/japplphysiol.00216.2007
Abstract
The phenomenon of length adaptation in airway smooth muscle (ASM) is well documented; however, the underlying mechanism is less clear. Evidence to date suggests that the adaptation involves reassembly of contractile filaments, leading to reconfiguration of the actin filament lattice and polymerization or depolymerization of the myosin filaments within the lattice. The time courses for these events are unknown. To gain insights into the adaptation process, we examined ASM mechanical properties and ultrastructural changes during adaptation. Step changes in length were applied to isolated bundles of ASM cells; changes in force, shortening velocity, and myosin filament mass were then quantified. A greater decrease in force was found following an acute decrease in length, compared with that of an acute increase in length. A decrease in myosin filament mass was also found with an acute decrease in length. The shortening velocity measured immediately after the length change was the same as that measured after the muscle had fully adapted to the new length. These observations can be explained by a model in which partial adaptation of the muscle leads to an intermediate state in which reconfiguration of the myofilament lattice occurred rapidly, followed by a relatively slow process of polymerization of myosin filaments within the lattice. The partially adapted intermediate state is perhaps more physiologically relevant than the fully adapted state seen under static conditions, and it simulates a more realistic behavior for ASM in vivo.Keywords
This publication has 33 references indexed in Scilit:
- Fast and slow dynamics of the cytoskeletonNature Materials, 2006
- Models of contractile units and their assembly in smooth muscleCanadian Journal of Physiology and Pharmacology, 2005
- Cytoskeletal remodelling and slow dynamics in the living cellNature Materials, 2005
- `Sarcomeres' of smooth muscle: functional characteristics and ultrastructural evidenceJournal of Cell Science, 2005
- Electron microscopic study of actin polymerization in airway smooth muscleAmerican Journal of Physiology-Lung Cellular and Molecular Physiology, 2004
- Influence of calcium on myosin thick filament formation in intact airway smooth muscleAmerican Journal of Physiology-Cell Physiology, 2002
- Scaling the Microrheology of Living CellsPhysical Review Letters, 2001
- Actin-facilitated assembly of smooth muscle myosin induces formation of actomyosin fibrilsThe Journal of cell biology, 1992
- Length vs. active force relationship in single isolated smooth muscle cellsAmerican Journal of Physiology-Cell Physiology, 1991
- Myosin Phosphorylation and the Cross-Bridge Cycle in Arterial Smooth MuscleScience, 1981