Changes in biophysical and biochemical properties of single bronchial smooth muscle cells from asthmatic subjects.
Whether contractility of bronchial smooth muscle cells (BSMC) from asthmatic subjects is significantly altered has never been validated. We tested the hypothesis that such BSMC show increased contractility. Cells were isolated from endobronchial biopsies. BSMC shortening was measured under an inverted microscope. Statistically significant increases in maximum shortening capacity (Delta L max) and velocity (Vo) were found in asthmatic BSMC compared with normal cells. Mean Delta L max in asthmatic BSMC was 39.05 +/- 1.99% (SE) of resting cell length compared with 28.6 +/- 1.1% in normal cells; mean Vo was 7.2 +/- 0.8% of resting cell length/s in asthmatic cells and 5.23 +/- 0.46% in normal cells. To investigate the mechanism of the increased contractility, we measured mRNA abundance of smooth muscle types of myosin light chain kinase (smMLCK) and myosin heavy chain. RT-PCR data revealed that smMLCK mRNA was higher in asthmatic BSMC (0.106 +/- 0.021 arbitrary densitometric units, n = 7) than in control cells (0.04 +/- 0.008, n = 11; P < 0.05). Messages for myosin heavy chain isoforms showed no difference. Increased kinase message content is an index of the mechanism for the increased velocity and capacity of shortening we report.
Ma
Xuefei
X
Departments of Physiology and Surgery, Faculty of Medicine, University of Manitoba, Manitoba, Winnipeg R3E 3J7, Canada.
Cheng
Zhaoqin
Z
Kong
Hong
H
Wang
Ying
Y
Unruh
Helmut
H
Stephens
Newman L
NL
Laviolette
Michel
M
D000328:Adult; D001249:Asthma / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D055592:Biophysical Phenomena; D001703:Biophysics; D001980:Bronchi / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D016084:Bronchoconstriction; D035061:Control Groups; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
D012333:RNA, Messenger; D009219:Myosin-Light-Chain Kinase; D018995:Myosin Heavy Chains