title: Mechanical strain increases cell stiffness through cytoskeletal filament reorganization.
abstract: We tested the hypothesis that cytoskeletal reorganization induced by cyclic strain increases cytoskeletal stiffness (G'). G' was measured by optical magnetic twisting cytometry in control cells and cells that had received mechanical strain for 10-12 days. G' was measured before and after both contractile and relaxant agonists, and in the strained cells both parallel (Para) and perpendicular (Perp) to the aligned cytoskeleton. Before activation, G' Para was 24 +/- 5% (+/- SE) greater compared with Perp (P < 0.05), and 35% +/- 6 greater compared with control (Cont, P < 0.01). The difference between strained and control cells was enhanced by KCl, increasing G' 171 +/- 7% Para compared with 125 +/- 6% Perp and 129 +/- 8% Cont (P < 10-5 both cases). The decrease in G' from baseline due to relaxant agonists isoproterenol and dibutyryl cAMP was similar in all groups. Long-term oscillatory loading of airway smooth muscle (ASM) cells caused stiffness to increase and become anisotropic. These findings are consistent with the hypothesis that cytoskeletal reorganization can enhance ASM stiffness and contractility. They imply, furthermore, that oscillatory loading of ASM may contribute to airway narrowing and failure of airway dilation in asthma.
authors.affiliation: Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Smith
authors.forename: Linhong
authors.initials: L
authors.lastname: Deng
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Fredberg
authors.forename: Geoffrey N
authors.initials: GN
authors.lastname: Maksym
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D048429:Cell Size / Q000187:drug effects / Q000502:physiology*; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D004285:Dogs; D016018:Least-Squares Analysis; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D011189:Potassium Chloride / Q000494:pharmacology; D012044:Regression Analysis; D013314:Stress, Mechanical; D014132:Trachea / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure
chemical_list: D011189:Potassium Chloride