Effect of oxidative stress on Rho kinase II and smooth muscle contraction in rat stomach

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 enzyme-linked 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.

The Impact of Oxidative Stress in Human Pathology: Focus on Gastrointestinal Disorders

“…In particular, the decrease of RhoA/ROCK expression, both at the transcriptional and translational levels, was reverted by the activity of SOD, thus demonstrating its link with oxidative stress [ 159 ]. However, these data disagree with a previous observation made on rat gastric muscle in which oxidative stress induced an activation of Rho kinase II with a consequent increase in Ach-induced contraction [ 160 ]. Nevertheless, in a later study, Singh and co-authors described a bimodal effect of oxidative stress in IAS basal tone.…”

Effect of progesterone on nitric oxide/cyclic guanosine monophosphate signaling and contraction in gastric smooth muscle cells

“…Measurement of contraction in dispersed GSMCs. Contraction of isolated muscle cells was measured by scanning micrometry as described previously (23,24). In brief, aliquots of cell suspension from 10 of the rats each containing ~10 4 cells/ml were added to HEPES medium and randomly distributed into either control or progesterone-treated groups.…”

“…The cells were viewed using a x10 or x20 objective of an inverted Nikon TMS-f microscope (Nikon Corporation, Tokyo, Japan), and cell images were acquired using a Canon digital camera (Canon Inc., Tokyo, Japan) and ImageJ acquisition software (version 1.45s; National Institutes of Health, Bethesda, MA, USA). The length of 50 muscle cells treated with the contractile agent (ACh) was measured at random by scanning micrometry (23,24). This was then compared with the length of untreated cells.…”

Regulation of Spontaneous Contractions in Intact Rat Bladder Strips and the Effects of Hydrogen Peroxide

“…In addition, ROCK inhibitor Y-27632 significantly inhibited the H 2 O 2 -elicited increase of basal tension, suggesting that H 2 O 2 may increase Ca 2+ sensitivity by regulation of the ROCK pathway. Multiple studies have demonstrated that H 2 O 2 can enhance the activation of ROCK and mediate vascular contraction [ 54 , 55 ]. In spontaneously hypertensive rats, increased ROCK activation was involved in the H 2 O 2 -induced contraction of mesenteric resistance arteries [ 55 ].…”