Abstract:
Thin filament-associated proteins such as calponin,
caldesmon, and smoothelin are believed to regulate
acto-myosin interaction and thus, muscle contraction.
Oxidative stress has been found to affect the normal contractile
behavior of smooth muscle and is involved in the
pathogenesis of a number of human diseases such as diabetes
mellitus, hypertension, and atherosclerosis. However,
very little is known about the effect of oxidative stress on
the expression of smooth muscle contractile proteins. The
aim of the current study is to investigate the effect of
oxidative stress on the expression of thin filament-associated
proteins in rat gastric smooth muscle. Single smooth
muscle cells of the stomach obtained from Sprague?Dawley
rats were used. Muscle cells were treated with hydrogen
peroxide (H2O2) (500 lM) for 30 min or the peroxynitrite
donor 3-morpholinosydnonimine (SIN-1) (1 mM) for
90 min to induce oxidative stress. Calponin, caldesmon,
and smoothelin expressions were measured via specifically
designed enzyme-linked immunosorbent assay. We found
that exposure to exogenous H2O2 or incubation of dispersed
gastric muscle cells with SIN-1 significantly
increased the expression of calponin, caldesmon, and
smoothelin proteins. In conclusion: oxidative stress
increases the expression of thin filament-associated proteins
in gastric smooth muscle, suggesting an important
role in gastrointestinal motility disorders associated with
oxidative stress.