Article,
Ultrastructure of airway smooth muscle
RESPIRATORY PHYSIOLOGY & NEUROBIOLOGY, 137 (2-3): 197-208 (September 2003)
DOI: {10.1016/S1569-9048(03)00147-2}
Abstract
There is an abundance of ultrastructural data in the literature on
vascular, visceral, and other smooth muscles; such data on airway smooth
muscle, however, are conspicuously missing. Here we present a series of
electron micrographs depicting contractile and cytoskeletal elements as
well as organelles in porcine trachealis. Myosin thick filaments are
present in the relaxed muscle; thick filament density increases
substantially when the muscle is activated. Actin thin filaments are
present in large excess over the thick filaments; the thin/thick
filament ratio is about 31/1 in the relaxed state; this ratio is reduced
to about 22/1 when the muscle is activated. The sarcoplasmic reticulum
is often found associated with caveolae and mitochondria. Cells within a
bundle are well connected by intermediate and gap junctions. The results
demonstrate that quantitative morphological analysis of ultrastructure
of airway smooth muscle fixed under different functional states is
possible and will be essential in elucidating the structural basis of
adaptation and contraction of the muscle. (C) 2003 Elsevier B.V. All
rights reserved.
