Cytotoxicity and genome-wide microarray analysis of intestinal smooth muscle cells in response to hexavalent chromium induction

Chronic ingestion of high concentrations of hexavalent chromium[Cr(VI)]in drinking water induces intestinal tumors in mice;however,information on its toxicity on intestinal smooth muscle cells is limited.The present study aimed to assess the in vitro and in vivo toxicological effects of Cr(VI)on intestinal smooth muscle cells.Human intestinal smooth muscle cells(HISM cells)were cultured with different concentrations of Cr(VI)to evaluate effects on cell proliferation ability,oxidative stress levels,and antioxidant system.Furthermore,tissue sections in Cr(VI)exposed rabbits were analyzed to evaluate toxicity on intestinal muscle cells in vivo.Gene chips were utilized to assess differential gene expression profiles at the genome-wide level in 1μmol/L Cr(VI)treated cells.Intestinal tissue biopsy results showed that Cr(VI)increased the incidences of diffuse epithelial hyperplasia in intestinal jejunum but caused no obvious damage to the structure of the muscularis.Cell proliferation analysis revealed that high concentrations(≥64μmol/L)but not low concentrations of Cr(VI)(≤16μmol/L)significantly inhibited the growth of HISM cells.For oxidative stress levels,the expression of reactive oxygen species(ROS)and nitric oxide(NO)was elevated at high concentrations(≥64μmol/L)but not at low concentrations of Cr(VI)(≤16μmol/L).In addition,dose-dependent increases in the activity of oxidized glutathione(GSSH)/total-glutathione(T-GSH)were also observed.Gene chip screened 491 differentially expressed genes including genes associated with cell apoptosis,oxidations,and cytoskeletons.Some of these differentially expressed genes may be unique to smooth muscle cells in response to Cr(VI)induction.

Effect of the ginsenoside Rb1 on the spontaneous contraction of intestinal smooth muscle in mice

AIM: To investigate the effect and the possible mechanism of ginsenoside Rb1 on small intestinal smooth muscle motility in mice. METHODS: Intestinal smooth muscle strips were isolated from male ICR mice (5 wk old), and the effect of ginsenoside Rb1 on spontaneous contraction was recorded with an electrophysiolograph. The effect of ginsenoside Rb1 on ion channel currents, including the voltage-gated K + channel current (IK V ), calcium-activated potassium channel currents (IK Ca ), spontaneous transient outward currents and ATP-sensitive potassium channel current (IK ATP ), was recorded on freshly isolated single cells using the whole-cell patch clamp technique. RESULTS: Ginsenoside Rb1 dose-dependently inhibited the spontaneous contraction of intestinal smooth muscle by 21.15% ± 3.31%, 42.03% ± 8.23% and 67.23% ± 5.63% at concentrations of 25 μmol/L, 50 μmol/L and 100 μmol/L, respectively (n=5,P<0.05). The inhibitory effect of ginsenoside Rb1 on spontaneous contraction was significantly but incompletely blocked by 10 mmol/L tetraethylammonium or 0.5 mmol/L 4-aminopyridine, respectively (n=5, P<0.05). However, the inhibitory effect of ginsenoside Rb1 on spontaneous contraction was not affected by 10 μmol/L glibenclamide or 0.4 μmol/L tetrodotoxin. At the cell level, ginsenoside Rb1 increased outward potassium currents, and IK V was enhanced from 1137.71 ± 171.62 pA to 1449.73 ± 162.39 pA by 50 μmol/L Rb1 at +60 mV (n=6, P<0.05). Ginsenoside Rb1 increased IK Ca and enhanced the amplitudes of spontaneous transient outward currents from 582.77 ± 179.09 mV to 788.12 ± 278.34 mV (n=5, P<0.05). However, ginsenoside Rb1 (50 μmol/L) had no significant effect on IK ATP (n=3, P<0.05). CONCLUSION: These results suggest that ginsenoside Rb1 has an inhibitory effect on the spontaneous contraction of mouse intestinal smooth muscle mediated by the activation of IK V and IK Ca , but the K ATP channel was not involved in this effect.

Cytotoxicity and genome-wide microarray analysis of intestinal smooth muscle cells in response to hexavalent chromium induction

Chronic ingestion of high concentrations of hexavalent chromium [Cr（VI）] in drinking water induces intestinal tumors in mice; however, information on its toxicity on intestinal smooth muscle cells is limited. The present study aimed to assess the in vitro and in vivo toxicological effects of Cr（VI） on intestinal smooth muscle cells. Human intestinal smooth muscle cells （HISM cells） were cultured with different concentrations of Cr（VI） to evaluate effects on cell proliferation ability, oxidative stress levels, and antioxidant system. Furthermore, tissue sections in Cr（VI） exposed rabbits were analyzed to evaluate toxicity on intestinal muscle cells in vivo. Gene chips were utilized to assess differential gene expression profiles at the genome-wide level in 1 gmol/L Cr（VI） treated cells. Intestinal tissue biopsy results showed that Cr（VI） increased the incidences of diffuse epithelial hyperplasia in intestinal jejunum but caused no obvious damage to the structure of the muscularis. Cell proliferation analysis revealed that high concentrations （〉__64 gmol/L） but not low concentrations of Cr（VI） （〈16 ~tmol/L） significantly inhibited the growth of HISM cells. For oxidative stress levels, the expression of reactive oxygen species （ROS） and nitric oxide （NO） was elevated at high concentrations （〉64 pmol/L） but not at low concentrations of Cr（VI） （〈16 pmol/L）. In addition, dose-dependent increases in the activity of oxidized glutathione （GSSH）/total-glutathione （T-GSH） were also observed. Gene chip screened 491 differentially expressed genes including genes associated with cell apoptosis, oxidations, and cytoskeletons. Some of these differentially expressed genes may be unique to smooth muscle cells in response to Cr（VI） induction.

Synthesis and Structural Features of 3,5-Dihydroxy N′-(3-nitrobenzylidene) Benzohydrazide and Its Effect on the Intestinal Smooth Muscle

A new compound,3,5-dihydroxy-N-（3-nitrobenzylidene）benzohydrazide （DNBB） methanol solvate,was synthesized and characterized by single-crystal X-ray diffraction.DNBB crystallizes in a monoclinic system,space group P2 1/c with a=8.387（4）,b=23.237（10）,c=9.133（3）,β=122.10（3）o,Z=4,V=1507.8（12） 3,D c=1.464 g/cm 3,F（000）=696.0,μ=0.116 mm-1,the final R=0.0480 and wR=0.1294.DNBB exhibited low toxicity on Caco-2 cell culture and produced significant inhibitory effect on the contraction of rat jejunal longitudinal smooth muscle （JLSM）.The mechanism of DNBB on JLSM was correlated to the stimulation of α and β adrenergic receptors since α receptor antagonist phentolamine and β receptor antagonist propranolol abolished the inhibitory effects of DNBB on the contraction of JLSM,respectively.