Mechanical strain increases contractile enzyme activity in cultured
airway smooth muscle cells.
Smith, P. G., T. Tokui, M. Ikebe.
Departments of Pediatrics and Physiology and Biophysics, Case
Western Reserve University, Cleveland, Ohio 44106
APStracts 2:0021L, 1995.
Smooth muscle hypertrophy is often found in tissue subjected to
abnormal physical stress. To determine if physical stress (strain)
per se could increase the contractile potential of airway smooth
muscle (ASM), we compared cultured ASM cells subjected to strain to
control cells (no strain) for rates of 1) myosin light chain kinase
(MLCK) mediated myosin light chain (LC20) phosphorylation, 2) actin
activated myosin ATPase and 3) myosin light chain phosphatase
mediated myosin dephosphorylation. Lysates from strained cells showed
increases in both LC20 phosphorylation activity and actomyosin ATPase
activity but decreased rates of phosphatase dependent myosin
dephosphorylation. The increased LC20 phosphorylation activity and
ATPase activity of the strained cells were accompanied by increases
in cellular content of MLCK and myosin respectively compared to
control. Because the cultured ASM cells exposed to strain expressed
higher MLCK activity and actomyosin ATPase activity but lower myosin
light chain phosphatase activity, these data suggest that physical
stress in part determines ASM potential for contractile state.
Received 8 September 1994; accepted in final form 13 February
1995.
APS Manuscript Number L269-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 February 1995.