Yong-Xiao Cao

Hydrogen sulfide protects from intestinal ischaemia-reperfusion injury in rats.

Objectives Hydrogen sulfide (H2S) is an endogenously gaseous mediator, regulating many pathophysiological functions in mammalian cells. H2S has been shown to inhibit myocardial ischaemia–reperfusion (I/R) injury. However, little is known about whether H2S could modulate intestinal I/R injury. This study aimed to investigate the effect of H2S on intestinal I/R injury and potential mechanism(s) underlying the action of H2S in regulating the development of intestinal I/R injury in rats.

Lipid-soluble smoke particles damage endothelial cells and reduce endothelium-dependent dilatation in rat and man

BackgroundCigarette smoking is a strong risk factor for vascular disease and known to cause dysfunction of the endothelium. However, the molecular mechanisms involved are still not fully understood.MethodsIn order to reveal the direct effects of lipid-soluble smoke particles on the endothelium, ring segments isolated from rat mesenteric arteries and human middle cerebral arteries (MCA) obtained at autopsy were incubated for 6 to 48 hrs in the presence of dimethylsulphoxide (DMSO)-soluble particles from cigarette smoke (DSP), i.e. lipid-soluble smoke particles. The endothelial microstructure was examined by transmission electron microscopy. The endothelial function was evaluated by acetylcholine (ACh)-induced endothelium-dependent vasodilatation, using a sensitive myograph.ResultsAfter DSP treatment, the arterial endothelium was swollen and loosing its attachment. In functional tests, the total ACh-induced dilatation, the nitric oxide (NO)-mediated and the endothelium-derived hyperpolarization factor (EDHF)-mediated dilatations were significantly decreased by DSP in a time- and concentration-dependent manner (p < 0.05). Nicotine, an important compound in cigarette smoke had, in an equivalent concentration as in DSP, no such effects (p > 0.05). Similar results were obtained in the human MCA.ConclusionThus, we demonstrate that the lipid-soluble smoke particles, but not nicotine, caused damage to arterial endothelium and reduced the endothelium-dependent dilatation in man and rat.

Black seed oil ameliorates allergic airway inflammation by inhibiting T-cell proliferation in rats

The black seeds, from the Ranunculaceae family, have been traditionally used by various cultures as a natural remedy for several ailments. In this study, we examined the effect of black seed oil as an immunomodulator in a rat model of allergic airway inflammation. Rats sensitized to ovalbumin and challenged intranasally with ovalbumin to induce an allergic inflammatory response were compared to ovalbumin-sensitized, intranasally ovalbumin-exposed rats pretreated with intraperitoneally administered black seed oil and to control rats. The levels of IgE, IgG1 and ova-specific T-cell proliferation in spleen were measured by ELISA. The pro-inflammatory cytokine IL-4, IL-5, IL-6 and TGF-beta1 mRNA expression levels were measured by reverse transcription polymerase chain reaction. The intraperitoneal administration of black seed oil inhibited the Th2 type immune response in rats by preventing inflammatory cell infiltration and pathological lesions in the lungs. It significantly decreased the nitric oxide production in BALF, total serum IgE, IgG1 and OVA-specific IgG1 along with IL-4, IL-5, IL-6 and TGF-beta1 mRNA expression. Black seed oil treatment resulted in decreased T-cell response evident by lesser delayed type hypersensitivity and lower T-cell proliferation in spleen. In conclusion, black seed oil exhibited a significant reduction in all the markers of allergic inflammation mainly by inhibiting the delayed type hypersensitivity and T-cell proliferation. The data suggests that inhibition of T-cell response may be responsible for immunomodulatory effect of black seed oil in the rat model of allergic airway inflammation.

Cigarette Smoke Upregulates Rat Coronary Artery Endothelin Receptors In Vivo

Background Cigarette smoking is a strong cardiovascular risk factor and endothelin (ET) receptors are related to coronary artery diseases. The present study established an in vivo secondhand smoke (SHS) exposure model and investigated the hypothesis that cigarette smoke induces ET receptor upregulation in rat coronary arteries and its possible underlying mechanisms. Methodology/Principal Findings Rats were exposed to SHS for 200 min daily for 8 weeks. The coronary arteries were isolated and examined. The vasoconstriction was studied by a sensitive myograph. The expression of mRNA and protein for receptors was examined by real-time PCR, Western blot and immunofluorescence. Compared to fresh air exposure, SHS increased contractile responses mediated by endothelin type A (ETA) and type B (ETB) receptors in coronary arteries. In parallel, the expression of mRNA and protein for ETA and ETB receptors of smoke exposed rats were higher than that of animals exposed to fresh air, suggesting that SHS upregulates ETA and ETB receptors in coronary arteries in vivo. Immunofluorescence staining showed that the enhanced receptor expression was localized to the smooth muscle cells of coronary arteries. The protein levels of phosphorylated (p)-Raf-1 and p-ERK1/2 in smoke exposed rats were significantly higher than in control rats, demonstrating that SHS induces the activation of the Raf/ERK/MAPK pathway. Treatment with Raf-1 inhibitor GW5074 suppressed SHS-induced enhanced contraction mediated by ETA receptors, and inhibited the elevated mRNA and protein levels of ETA and ETB receptors caused by SHS. The results of correlation and regression analysis showed that phosphorylation of Raf and ERK1/2 were independent determinants to affect protein expression of ETB and ETA receptors. Conclusions/Significance Cigarette smoke upregulates ETB and ETA receptors in rat coronary artery, which is associated with the activation of the Raf/ERK/MAPK pathway.

Induces vasodilatation of rat mesenteric artery in vitro mainly by inhibiting receptor-mediated Ca2+-influx and Ca2+-release

The purpose of this study was to investigate the effect of atropine on peripheral vasodilation and the mechanisms involved. The isometric tension of rat mesenteric artery rings was recordedin vitro on a myograph. The results showed that atropine, at concentrations greater than 1 μM, relaxed the noradrenalin (NA)-precontracted rat mesenteric artery in a concentration-dependent manner. Atropine-induced vasodilation was mediated, in part, by an endothelium-dependent mechanism, to which endothelium-derived hyperpolarizing factor may contribute. Atropine was able to shift the NA-induced concentration-response curve to the right, in a non-parallel manner, suggesting the mechanism of atropine was not mediated via the α1-adrenoreceptor. The β-adrenoreceptor and ATP sensitive potassium channel, a voltage dependent calcium channel, were not involved in the vasodilatation. However, atropine inhibited the contraction derived from NA and CaCl2 in Ca2+-free medium, in a concentration dependent manner, indicating the vasodilatation was related to the inhibition of extracellular Ca2+ influx through the receptor-operated calcium channels and intracellular Ca2+ release from the Ca2+ store. Atropine had no effect on the caffeine-induced contraction in the artery segments, indicating the inhibition of intracellular Ca2+ release as a result of atropine most likely occurs via the IP3 pathway rather than the ryanodine receptors. Our results suggest that atropine-induced vasodilatation is mainly from artery smooth muscle cells due to inhibition of the receptor-mediated Ca2+-influx and Ca2+-release, and partly from the endothelium mediated by EDHF.

The Raf-1 inhibitor GW5074 and dexamethasone suppress sidestream smoke-induced airway hyperresponsiveness in mice.

BackgroundSidestream smoke is closely associated with airway inflammation and hyperreactivity. The present study was designed to investigate if the Raf-1 inhibitor GW5074 and the anti-inflammatory drug dexamethasone suppress airway hyperreactivity in a mouse model of sidestream smoke exposure.MethodsMice were repeatedly exposed to smoke from four cigarettes each day for four weeks. After the first week of the smoke exposure, the mice received either dexamethasone intraperitoneally every other day or GW5074 intraperitoneally every day for three weeks. The tone of the tracheal ring segments was recorded with a myograph system and concentration-response curves were obtained by cumulative administration of agonists. Histopathology was examined by light microscopy.ResultsFour weeks of exposure to cigarette smoke significantly increased the mouse airway contractile response to carbachol, endothelin-1 and potassium. Intraperitoneal administration of GW5074 or dexamethasone significantly suppressed the enhanced airway contractile responses, while airway epithelium-dependent relaxation was not affected. In addition, the smoke-induced infiltration of inflammatory cells and mucous gland hypertrophy were attenuated by the administration of GW5074 or dexamethasone.ConclusionSidestream smoke induces airway contractile hyperresponsiveness. Inhibition of Raf-1 activity and airway inflammation suppresses smoking-associated airway hyperresponsiveness.

The severe adverse reaction to vitamin k1 injection is anaphylactoid reaction but not anaphylaxis.

The severe adverse reaction to vitamin K1 injection is always remarkable and is thought to result from anaphylaxis. Paradoxically, however, some patients administered vitamin K1 injection for the first time have adverse reactions. Using beagle dogs, the present study tested the hypothesis that the response to vitamin K1 is an anaphylactoid reaction. The results showed that serious anaphylaxis-like symptoms appeared in beagle dogs after the administration of vitamin K1 injection for the first time. The plasma histamine concentration increased, and blood pressure decreased sharply. After sensitization, dogs were challenged with vitamin K1 injection and displayed the same degree of symptoms as prior to sensitization. However, when the vitamin K1 injection-sensitized dogs were challenged with a vitamin K1-fat emulsion without solubilizers such asTween-80, the abnormal reactions did not occur. Furthermore, there was no significant change in the plasma immunoglobulin E concentration after vitamin K1 challenge. Following treatment with vitamin K1 injection, the release of histamine and β-hexosaminidase by rat basophilic leukemia-2H3 cells as well as the rate of apoptosis increased. The Tween-80 group displayed results similar to those observed following vitamin K1 injection in vivo. However, the dogs in the vitamin K1-fat emulsion group did not display any abnormal behavior or significant change in plasma histamine. Additionally, degranulation and apoptosis did not occur in rat basophilic leukemia-2H3 cells. Our results indicate that the adverse reaction induced by vitamin K1 injection is an anaphylactoid reaction, not anaphylaxis. Vitamin K1 injection induces the release of inflammatory factors via a non-IgE-mediated immune pathway, for which the trigger may be the solubilizer.

Secondhand smoke exposure induces Raf/ERK/MAPK-mediated upregulation of cerebrovascular endothelin ETA receptors.

BackgroundCigarette smoking enhances the risk of stroke. However, the underlying molecular mechanisms are largely unknown. The present study established an in vivo rat secondhand cigarette smoking (SHS) model and examined the hypothesis that SHS upregulates endothelin receptors with increased cerebrovascular contraction via the Raf/extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinases (MAPK) pathway.ResultsRats were exposed to SHS for up to 8 weeks. The cerebral artery vasoconstriction was recorded by a sensitive myograph. The mRNA and protein expressions for endothelin receptors in cerebral arteries were studied by real-time PCR and Western blot. Compared to fresh air exposed rats, cerebral arteries from SHS rats exhibited stronger contractile responses (P < 0.05) mediated by endothelin type A (ETA) receptors. The expressions of mRNA and protein for ETA receptors in the cerebral arteries from SHS rats were higher (P < 0.05) than that in control. SHS did not affect endothelin type B (ETB) receptor-mediated contractions, mRNA or protein levels. The results suggest that SHS upregulates ETA, but not ETB receptors in vivo. After SHS exposure, the mRNA levels of Raf-1 and ERK1/2, the protein expression of phosphorylated (p)-Raf-1 and p-ERK1/2 were increased (P < 0.05). Raf-1 inhibitor, GW5074 suppressed the enhanced ETA receptor-mediated contraction, mRNA and protein levels induced by SHS. In addition, GW5074 inhibited the SHS-caused increased mRNA and phosphorylated protein levels of Raf-1 and ERK1/2, suggesting that SHS induces activation of the Raf/ERK/MAPK pathway.ConclusionsSHS upregulates cerebrovascular ETA receptors via the Raf/ERK/MAPK pathway, which provides novel understanding of mechanisms involved in SHS-associated stroke.

Lipid soluble smoke particles upregulate endothelin receptors in rat basilar artery

The present study examines the effect of dimethylsulphoxide-soluble particles (DSP) from cigarette smoke on endothelin (ET) receptors in the basilar artery. The contractile responses to ET-1 (ET(A) and ET(B) receptors agonist) and sarafotoxin 6c (ET(B) receptor agonist) were studied using a sensitive myograph. The mRNA levels of ET receptors were determined with real-time PCR, while the protein level was evaluated by immunohistochemistry. The results showed that a DSP concentration of 0.4 microl/ml increased the contractile responses induced by sarafotoxin 6c and ET-1 and the mRNA and protein levels of the ET receptors. Inhibitor SB203580 (a p38 inhibitor), staurosporine (a PKC inhibitor) or wedelolactone (a NF-kappaB inhibitor) attenuated the elevated sarafotoxin 6c-induced contraction, the increased mRNA expression and protein levels of the ET(B) receptor induced by DSP. The effects on the ET(A) receptor induced by DSP 0.4 microl/ml were inhibited by co-incubation with PD98059 (an ERK1/2 inhibitor) or SP600125 (a JNK inhibitor) and were further enhanced by SB203580. The results indicate that DSP 0.4 microl/ml upregulates the ET(B) receptor of basilar arterial smooth muscle cells via activation of the p38 pathway and transcriptional factor NF-kappaB, while also upregulating the ET(A) receptor via activation of the ERK1/2 and JNK pathways. Additionally, the p38 pathway seems to be involved in the feedback regulation of the ET(A) receptor.

Minimally modified LDL upregulates endothelin type B receptors in rat basilar artery

Minimally modified low density lipoprotein (mmLDL) is a well-known risk factor for cerebral vascular diseases and upregulation of endothelin type B (ET(B)) receptors plays key roles in the pathogenesis. The present study was designed to examine if mmLDL upregulated endothelin ET(B) receptors in basilar artery and its possible intracellular signaling molecular mechanisms. Rat basilar arteries were cultured for 24h in the presence of mmLDL with specific inhibitors. The artery contractile responses and receptor expressions of mRNA and protein were investigated using myograph system, real-time PCR and Western blot techniques, respectively. Results showed that ET(B) receptor agonist, sarafotoxin 6c induced a weak contraction in fresh basilar artery segments. After organ culture the contraction curve mediated by ET(B) receptor was shifted towards the left with an increased E(max) of 88 ± 6%. The mmLDL 10 μg/mL further shifted the concentration-contractile curves towards the left with an increased E(max) of 116 ± 12%. The organ culture significantly increased ET(B) receptor mRNA and protein levels from fresh arteries, which was further enhanced by mmLDL. The staurosporine (PKC inhibitor), both SB386023 and U0126 (extracellular signal related kinases 1 and 2 inhibitor), and wedelolactone (NF-κB inhibitor) almost totally abolished organ culture-increased and mmLDL-increased contraction and expressions of endothelin ET(B) receptor. SP600125 (C-jun terminal kinase inhibitor) and SB203580 (p38 inhibitor) attenuated both organ cultured-induced and mmLDL-induced upregulation of endothelin ET(B) receptors. In conclusion, mmLDL upregulates ET(B) receptors of cerebral basilar artery via the PKC, MAPK and NF-κB signal pathways.