Abstract:
Recent studies have shown that both Rho kinase signaling and oxidative stress are 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 gastrointestinal (GI) smooth muscle Rho kinase pathway. The aim of the current study was to
investigate the effect of oxidative stress on Rho kinase II and muscle contraction in rat stomach. The peroxynitrite donor
3-morpholinosydnonimine (SIN-1), hydrogen peroxide (H2O2), and peroxynitrite were used to induce oxidative stress. Rho kinase
II expression and ACh-induced activity were measured in control and oxidant-treated cells via specifically designed enzymelinked
immunosorbent assay (ELISA) and activity assay kits, respectively. Single smooth muscle cell contraction was measured
via scanning micrometry in the presence or absence of the Rho kinase blocker, Y-27632 dihydrochloride. All oxidant agents
significantly increased ACh-induced Rho kinase II activity without affecting its expression level. Most important, oxidative stress
induced by all three agents augmented ACh-stimulated muscle cell contraction, which was significantly inhibited by Y-27632. In
conclusion, oxidative stress activates Rho kinase II and enhances contraction in rat gastric muscle, suggesting an important role
in GI motility disorders associated with oxidative stress.