Interaction among Hydrogen Sulfide and Other Gasotransmitters in Mammalian Physiology and Pathophysiology.

Hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and sulfur dioxide (SO2) were previously considered as toxic gases, but now they are found to be members of mammalian gasotransmitters family. Both H2S and SO2 are endogenously produced in sulfur-containing amino acid metabolic pathway in vivo. The enzymes catalyzing the formation of H2S are mainly CBS, CSE, and 3-MST, and the key enzymes for SO2 production are AAT1 and AAT2. Endogenous NO is produced from L-arginine under catalysis of three isoforms of NOS (eNOS, iNOS, and nNOS). HO-mediated heme catabolism is the main source of endogenous CO. These four gasotransmitters play important physiological and pathophysiological roles in mammalian cardiovascular, nervous, gastrointestinal, respiratory, and immune systems. The similarity among these four gasotransmitters can be seen from the same and/or shared signals. With many studies on the biological effects of gasotransmitters on multiple systems, the interaction among H2S and other gasotransmitters has been gradually explored. H2S not only interacts with NO to form nitroxyl (HNO), but also regulates the HO/CO and AAT/SO2 pathways. Here, we review the biosynthesis and metabolism of the gasotransmitters in mammals, as well as the known complicated interactions among H2S and other gasotransmitters (NO, CO, and SO2) and their effects on various aspects of cardiovascular physiology and pathophysiology, such as vascular tension, angiogenesis, heart contractility, and cardiac protection.

[Cardiovascular Regulation by Sulfur-containing Gaseous Signaling Molecules and the Underlying Mechanisms:Updated Research Evidence].

The sulfur-containing gases hydrogen sulfide (H2S)and sulfur dioxide (SO2 )were previously considered to be waste gases. Recent studies showed that they could be endogenously generated from metabolism of the sulfur-containing amino acids in mammals. Endogenous H2S and SO2 generation pathways also existed in the cardiovascular system.H2S and SO2 had important physiological effects in the cardio-vascular system including vasorelaxation and myocardial negative inotropic effect. The pathophysiological effects of H2S and SO2 in the cardiovascular system have been recognized, such as alleviating hypertension and pulmonary hypertension, inhibiting the development of atherosclerosis, and protecting against myocardial ischemia-reperfusion (I /R)injury and isoproterenol-induced myocardial injury. Adenosine triphosphate-sensitive potassium (KATP )channel, L-type calcium (L-Ca2 +) channel, cGMP, NF-κB signaling pathway and MAPK signaling pathway and so on participated in the biological effects of H2S and SO2 .The above findings suggested that H2S and SO2 were important endogenous gaseous signaling molecules in the cardiovascular system, which provided a new way to elucidate the pathogenesis and therapeutic targets of cardiovascular diseases.

[Effects of hydrogen sulfide donor on production of adrenomedullin and atrial natriuretic peptide in rats with atherosclerosis].

OBJECTIVE: Endogenous hydrogen sulfide (H2S), a novel gasotransmitter in cardiovascular regulation, plays an important protective role in the development and progression of atherosclerosis (AS). This study was designed to explore the effects of H2S donor on the production of adrenomedullin (ADM) and atrial natriuretic peptide (ANP) in AS rats. METHODS: Male Sprague-Dawley rats were randomly divided into control group (n=10), AS group (n=10), and AS+NaHS group (n=10). Rats in the AS and AS+NaHS groups were given 3-day intraperitoneal injections of vitamin D3 and 8-week high-fat diet to induce AS, and the rats in the AS+NaHS group were intraperitoneally injected with H2S donor NaHS. Oil red O staining was applied to detect changes in the areas of the atherosclerotic plaques in the aortic root and the coronary artery; sulfide-sensitive electrode method was used to measure the plasma concentration of H2S. ADM and ANP levels in plasma were determined by radioimmunoassay. RESULTS: Compared with the control group, marked atherosclerotic plaques were observed in the aortic root and the coronary artery in AS rats. Moreover, plasma H2S level decreased significantly, ADM level increased, and ANP level decreased significantly in AS rats (P<0.01). However, after the treatment with H2S donor NaHS for 8 weeks, the above changes in AS rats were reversed, demonstrated by significantly reduced areas of the atherosclerotic plaques in both the aortic root and the coronary artery, significantly increased plasma H2S level, significantly decreased plasma ADM level, and significantly increased plasma ANP level (P<0.01). CONCLUSIONS: H2S plays an important regulatory effect on vasoactive peptides ADM and ANP in AS rats.

[Clinical analysis and follow-up study of cardiavascular system involvement in 10 children with methylmalonic aciduria combined with hyperhomocysteinemia].

OBJECTIVE: To study the clinical features and treatment outcomes of cardiovascular system involvement in children with methylmalonic aciduria combined with hyperhomocysteinemia (MMACHC). METHODS: The clinical data of 10 children with methylmalonic aciduria combined with hyperhomocysteinemia and who had cardiovascular system involvement were retrospectively analyzed and the treatment outcomes were followed up. RESULTS: In the 10 patients, there were 4 cases with initial presentations of cardiovascular system symptoms such as shortness of breath and dyspnea, 3 cases with urinary tract symptoms such as edema, hematuria and proteinuria, and 3 cases with nervous system symptoms such as developmental retardation and convulsions. The 10 patients had different types and severity of cardiovascular injuries. After 3 months to 8 years of follow-up, the congenital heart defects resolved naturally in 2 cases, and the patient with arrhythmia had no obvious changes. In 5 cases of hypertension, blood pressures recovered to normal in 3 cases, and 1 case was lost to follow-up. In 5 patients with pulmonary hypertension, 2 died, 2 recovered, and 1 case had mildly elevated pulmonary artery pressure. Seven patients underwent MMACHC gene testing, and 5 showed c.80A>G mutations. CONCLUSIONS: Metabolic disease should be taken into account for the children with unexplained pulmonary hypertension and hypertension with the onset of the shortness of breath and dyspnea. The severity of cardiovascular system involvement might be one of the most important factors affecting the prognosis of children with MMACHC. Cardiavascular system involvement of the patients may be related to MMACHC c.80A>G mutations.

[Value of muscle enzyme analysis in differential diagnosis of childhood myopathic hyper-creatine kinase-emia].

OBJECTIVE: To summarize the etiology and clinical characteristics of children with myopathic elevated creatine kinase (CK) levels. The degrees of elevated CK as well as lactic dehydrogenase (LDH) and aspartate aminotransferase (AST) levels in different myopathy were analyzed. METHODS: The clinical data of 235 cases characterized as myopathic hyper-CK-emia from January 2004 to December 2011 were collected and analyzed. A retrospective analysis of LDH and AST levels according to CK in part of the patients were reviewed. RESULTS: Of the 235 cases, 180 were male and 55 female. According to the age at which hyper-CK-emia was diagnosed, 64 cases were under 6 months, 90 between 6 months and 3 years, 50 between 3 and 6 years and 31 between 6 and 14 years. Their CK levels significantly increased in 162 cases, moderately increased in 31 cases, and slightly increased in 42 cases. The age at which hyper-CK-emia was diagnosed and the CK level had no correlation with muscle weakness and the severity. As to CK levels: Duchenne muscular dystrophy (DMD) > inflammatory myopathies > congenital muscular dystrophy (CMD) > metabolic myopathies. LDH and AST levels: DMD > inflammatory myopathies > metabolic myopathies > CMD. CONCLUSION: Unlike adults, the etiology of myopathic hyper-CK-emia in children is complicated and diverse. The onset type, the degree and duration of hyper-CK-emia are helpful to make the diagnosis. CK increases most significantly in DMD, then in inflammatory myopathies, CMD, and metabolic myopathies. Diagnostic flowchart of myogenic hyper-CK-emia should follow a certain process, and the indications of biochemical tests, metabolic screening, electrophysiological examination, muscle biopsy and genetic testing should be made. Finally, different treatments should be designed according to the etiology.

Age and mean platelet volume-based nomogram for predicting the therapeutic efficacy of metoprolol in Chinese pediatric patients with vasovagal syncope.

BACKGROUND: Vasovagal syncope (VVS) is the most common type of orthostatic intolerance in children. We investigated whether platelet-related factors related to treatment efficacy in children suffering from VVS treated with metoprolol. METHODS: Metoprolol-treated VVS patients were recruited. The median duration of therapy was three months. Patients were followed and divided into two groups, treament-effective group and treatment-ineffective group. Logistic and least absolute shrinkage selection operator regressions were used to examine treatment outcome variables. Receiver-operating characteristic (ROC) curves, precision-recall (PR) curves, calibration plots, and decision curve analyses were used to evaluate the nomogram model. RESULTS: Among the 72 patients who complete the follow-up, treatment-effective group and treatment-ineffective group included 42 (58.3%) and 30 (41.7%) cases, respectively. The patients in the treatment-effective group exhibited higher mean platelet volume (MPV) [(11.0 ± 1.0) fl vs. (9.8 ± 1.0) fl, P < 0.01] and platelet distribution width [12.7% (12.3%, 14.3%) vs. 11.3% (10.2%, 12.2%), P < 0.01] than those in the treatment-ineffective group. The sex ratio was significantly different (P = 0.046). A fit model comprising age [odds ratio (OR) = 0.766, 95% confidence interval (CI) = 0.594-0.987] and MPV (OR = 5.613, 95% CI = 2.297-13.711) might predict therapeutic efficacy. The area under the curve of the ROC and PR curves was computed to be 0.85 and 0.9, respectively. The P value of the Hosmer-Lemeshow test was 0.27. The decision curve analysis confirmed that managing children with VVS based on the predictive model led to a net advantage ranging from 0.01 to 0.58. The nomogram is convenient for clinical applications. CONCLUSION: A novel nomogram based on age and MPV can predict the therapeutic benefits of metoprolol in children with VVS.

Sulfur dioxide preconditioning increases antioxidative capacity in rat with myocardial ischemia reperfusion (I/R) injury.

BACKGROUND: The study was designed to explore if sulfur dioxide (SO2) preconditioning increased antioxidative capacity in rat with myocardial ischemia reperfusion (I/R) injury. METHODS: The myocardial I/R model was made by left coronary artery ligation for 30min and reperfusion for 120min in rats. Myocardial infarct size and plasma lactate dehydrogenase (LDH) and creatine kinase (CK) activities, plasma superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px) and glutathione (GSH) changes were detected for the rats. The contents of myocardial hydrogen sulfide (H2S) and nitric oxide (NO) were measured. Myocardial protein expressions of SOD1, SOD2, cystathionine γ-lyase (CSE) and iNOS were tested using Western blot. RESULTS: Myocardial infarction developed and plasma CK and LDH activities were significantly increased in I/R group compared with those in control group, but SO2 preconditioning significantly reduced myocardial infarct size, and plasma CK and LDH activities. SO2 preconditioning successfully increased plasma SOD, GSH and GSH-Px levels and myocardial SOD1 protein expression, but decreased MDA level in rats of I/R group. Compared with controls, the myocardial H2S level and CSE expression were decreased after I/R, but myocardial NO level and iNOS expression were increased. With the treatment of SO2, myocardial H2S level and CSE expression were increased, but myocardial NO level and iNOS expression were decreased compared with those in I/R group. CONCLUSIONS: SO2 preconditioning could significantly reduce I/R-induced myocardial injury in vivo in association with increased myocardial antioxidative capacity, upregulated myocardial H2S/CSE pathway but downregulated NO/iNOS pathway.

The PI3K/Akt pathway mediates the protection of SO(2) preconditioning against myocardial ischemia/reperfusion injury in rats.

AIM: To explore the mechanisms underlying the protection by SO2 preconditioning against rat myocardial ischemia/reperfusion (I/R) injury. METHODS: Male Wistar rats underwent 30-min left coronary artery ligation followed by 120-min reperfusion. An SO2 donor (1 µmol/kg) was intravenously injected 10 min before the ischemia, while LY294002 (0.3 mg/kg) was intravenously injected 30 min before the ischemia. Plasma activities of LDH and CK were measured with an automatic enzyme analyzer. Myocardial infarct size was detected using Evans-TTC method. The activities of caspase-3 and -9 in myocardium were assayed using a commercial kit, and the levels of p-Akt, Akt, PI3K and p-PI3K were examined with Western blotting. RESULTS: Pretreatment with SO2 significantly reduced the myocardial infarct size and plasma LDH and CK activities, as well as myocardial caspase-3 and -9 activities in the rats. Furthermore, the pretreatment significantly increased the expression levels of myocardial p-Akt and p-PI3K p85. Administration of the PI3K inhibitor LY294002 blocked all the effects induced by SO2 pretreatment. CONCLUSION: The results suggest that the PI3K/Akt pathway mediates the protective effects of SO2 preconditioning against myocardial I/R injury in rats.

[Diagnostic values of heart rate variability on unexplained syncope in children].

OBJECTIVE: To investigate the diagnostic values of heart rate varibility (HRV) on unexplained syncope (UPS) in children. METHODS: Forty-nine children with unexplained syncope underwent head-up tilt test (HUT) and Holter monitering, then the differences were analyzed between HUT positive children and HUT negative children. The receiver operating characteristic (ROC) curve was used to explore the diagnostic values of HRV. RESULTS: Of the 49 patients, 32 (65.3%) were HUT positive. The diagnostic positive rate of HUT was 65.3%. The SDNNi, rMSSD, TP, ULF, VLF, LF and HF in the HUT positive group were significantly higher than those in the HUT negative group (P<0.05), respectively. There were no significant differences in SDNN, pNN50 and triangular index between the patients with different HUT outcomes (P>0.05). The ROC curve on the predictive values of SDNNi, rMSSD, TP, ULF, VLF, LF and HF showed that ULF, LF, and HF (12 947.00, 9 462.50, and 9 509.00) as cutting values produced both high sensitivity (75.0%, 68.8%, and 68.8%) and specificity (64.7%, 64.7%, and 64.7%) to predict the diagnostic values of HUT for diagnosing unexplained syncope. CONCLUSION: ULF, LF and HF can be considered as indicators for diagnosing neurally-mediated syncope in children. ULF, LF, and HF (12 947.00, 9 462.50, and 9 509.00) taken as cutting values may produce both high sensitivity and specificity.

[Significance of serum iron in the differential diagnosis between vasovagal syncope and postural orthostatic tachycardia syndrome in children].

OBJECTIVE: To explore the predictive value of serum iron in differentiating between vasovagal syncope (VVS) and postural orthostatic tachycardia syndrome (POTS) in children. METHODS: Totally 57 children (aged 4-17 years, POTS 40 cases, and VVS 17 cases) who were at the syncope clinic or admitted to the Department of Pediatrics, Peking University First Hospital from August 2009 to September 2012 were included in the study. The diagnoses were analyzed by the value of serum iron and receiver operating characteristic (ROC) curves used to explore the predictive value of different serum iron in differential diagnosis between VVS and POTS. RESULTS: There were significant differences in the median value of POTS [17.4 (interquartile range 13.5 -21.8) µmol/L] and VVS [8.9 (interquartile range 7.5-17.6) µmol/L] (P<0.01). When the value of serum iron was 11.8 µmol/L, the sensitivity and specificity of the differential diagnosis between VVS and POTS were 92.5% and 64.7%, respectively. CONCLUSION: The serum iron might be used as an initial diagnostic method in differential diagnosis between VVS and POTS, based on the history of the patients.

[Plasma prealbumin and C-reactive protein predicts coronary artery lesions in children with Kawasaki disease].

OBJECTIVE: To study the changes of plasma prealbumin (PA) and C-reactive protein (CRP) in children with Kawasaki disease, and to explore the importance of integral analysis of plasma PA and CRP in predicting the severity of coronary artery lesions in Kawasaki Disease. METHODS: In a retrorespective study, 108 children with Kawasaki disease admitted in our hospital were enrolled. The statistical methods included t test, Chi-square test, and ROC curve analysis. The changes of plasma PA and CRP during the disease were studied. Also, the usefulness of comprehensive analysis of PA and CRP in predicting the severity of coronary artery lesions was also evaluated. RESULTS: During the acute phase of Kawasaki disease, the plasma PA level was decreased distinctly, while the CRP level increased significantly. Among the 55 cases whose plasma PA level was <80 mg/L, setting CRP=76.5 mg/L as the cutoff value, the occurrence of coronary artery dilations for those with CRP level<76.5 mg/L was significantly higher than those with CRP level >76.5 mg/L (P<0.05). CONCLUSION: Plasma PA and CRP changed greatly during the process of Kawasaki disease. And it may be of importance in predicting the severity of coronary artery lesions, by using integrated plasma PA and CRP.

[Impact of H2S on oxidized-low density lipoprotein-stimulated nuclear factor-κB in human monocytes/macrophage and its mechanisms].

OBJECTIVE: To investigate the role of hydrogen sulfide (H2S) on oxidized-low density lipoprotein (ox-LDL)-stimulated NF-κB pathway in human monocytes/macrophages and its mechanisms. METHODS: THP-1 cells were induced to differentiate into macrophages by incubation with phorbol myristate acetate (PMA) . The human monocytes/macrophages were divided into 4 groups: control group, ox-LDL group, ox-LDL + H2S 100 µmol/L group and ox-LDL + H2S 500 µmol/L group. The expression of IκBα and phosphorylation of NF-κB p65 in the cells were detected by Western blotting. The expression of IκBα and nuclear translocation of NF-κB p65 in the cells were observed by laser confocal method. The interaction between NF-κB p65 and IκBα in the nuclear extracts was detected by coimmunoprecipitation method. RESULTS: Compared with the control group, the phosphorylation of NF-κB p65 in the human monocytes/macrophages of ox-LDL group was increased significantly (0.855 ± 0.116 vs. 0.502 ± 0.218, P=0.046), while the expression of IκBα in the cells of the ox-LDL group was decreased (0.612 ± 0.216 vs. 0.997 ± 0.167, P=0.029). Compared with the ox-LDL group, the phosphorylation of NF-κB p65 in the cells of the ox-LDL + H2S 100 µmol/L group and the ox-LDL + H2S 500 µmol/L group was decreased significantly (0.424 ± 0.225 vs. 0.855 ± 0.116, P=0.020; 0.378 ± 0.071 vs. 0.855 ± 0.116, P=0.011, respectively), while the expressions of IκBα in the cells of the ox-LDL + H2S 100 µmol/L group and the ox-LDL + H2S 500 µmol/L group were increased (1.037 ± 0.111 vs. 0.612 ± 0.216, P=0.015; 1.046 ± 0.084 vs. 0.612 ± 0.216, P=0.013, respectively). The results from laser confocal method demonstrated that the IκBα expression in the cytoplasma of cells in the ox-LDL group was lower than that in the control group, and the nuclear translocation of NF-κB p65 in the cells of the ox-LDL group was higher than that in the control group. The IκBα expression in the cytoplasma of cells in the ox-LDL+ H2S 100 µmol/L group and ox-LDL + H2S 500 µmol/L group was higher than that in the ox-LDL group, and the nuclear translocation of NF-κB p65 in the cells of ox-LDL group was lower than that in the ox-LDL group. The coimmunoprecipitation experiment showed that no IκBα integrated with NF-κB p65 was detected in the nuclear extracts of cells in the control group, a small amount of IκBα integrated with NF-κB p65 was detected in the nuclear extracts of cells in the ox-LDL group, but a large amount of IκBα integrated with NF-κB p65 was detected in the nuclear extracts of cells in the ox-LDL+H2S 100 µmol/L group and the ox-LDL + H2S 500 µmol/L group. CONCLUSION: H2S inhibited the activation of NF-κB p65 pathway in the ox-LDL-induced human monocytes/macrophages. The mechanisms might involve the prevention of the degradation of IκBα, then the inhibition of the phosphorylation and nuclear translocation of NF-κB p65, thus promoting the IκBα integrated with NF-κB p65 in the nuclei, and then inhibiting the activity of NF-κB.

A predictive model of response to metoprolol in children and adolescents with postural tachycardia syndrome.

BACKGROUND: The present work was designed to explore whether electrocardiogram (ECG) index-based models could predict the effectiveness of metoprolol therapy in pediatric patients with postural tachycardia syndrome (POTS). METHODS: This study consisted of a training set and an external validation set. Children and adolescents with POTS who were given metoprolol treatment were enrolled, and after follow-up, they were grouped into non-responders and responders depending on the efficacy of metoprolol. The difference in pre-treatment baseline ECG indicators was analyzed between the two groups in the training set. Binary logistic regression analysis was further conducted on the association between significantly different baseline variables and therapeutic efficacy. Nomogram models were established to predict therapeutic response to metoprolol. The receiver-operating characteristic curve (ROC), calibration, and internal validation were used to evaluate the prediction model. The predictive ability of the model was validated in the external validation set. RESULTS: Of the 95 enrolled patients, 65 responded to metoprolol treatment, and 30 failed to respond. In the responders, the maximum value of the P wave after correction (Pcmax), P wave dispersion (Pd), Pd after correction (Pcd), QT interval dispersion (QTd), QTd after correction (QTcd), maximum T-peak-to-T-end interval (Tpemax), and T-peak-to-T-end interval dispersion (Tped) were prolonged (all P < 0.01), and the P wave amplitude was increased (P < 0.05) compared with those of the non-responders. In contrast, the minimum value of the P wave duration after correction (Pcmin), the minimum value of the QT interval after correction (QTcmin), and the minimum T-peak-to-T-end interval (Tpemin) in the responders were shorter (P < 0.01, < 0.01 and < 0.01, respectively) than those in the non-responders. The above indicators were screened based on the clinical significance and multicollinearity analysis to construct a binary logistic regression. As a result, pre-treatment Pcmax, QTcmin, and Tped were identified as significantly associated factors that could be combined to provide an accurate prediction of the therapeutic response to metoprolol among the study subjects, yielding good discrimination [area under curve (AUC) = 0.970, 95% confidence interval (CI) 0.942-0.998] with a predictive sensitivity of 93.8%, specificity of 90.0%, good calibration, and corrected C-index of 0.961. In addition, the calibration curve and standard curve had a good fit. The accuracy of internal validation with bootstrap repeated sampling was 0.902. In contrast, the kappa value was 0.769, indicating satisfactory agreement between the predictive model and the results from the actual observations. In the external validation set, the AUC for the prediction model was 0.895, and the sensitivity and specificity were 90.9% and 95.0%, respectively. CONCLUSIONS: A high-precision predictive model was successfully developed and externally validated. It had an excellent predictive value of the therapeutic effect of metoprolol on POTS among children and adolescents.

[Modified methylene blue method for measurement of hydrogen sulfide level in plasma].

In past decade, hydrogen sulfide (H2S) as a novel gasotransmitter, covered many fields in biological and medical research. However, there is no effective, convenient and high-throughput method for determination of circulatory H2S until now. Here, we aim to develop an easy method for measurement of circulatory H2S by modified methylene blue method. In the present study, we added Zn²âº to plasma sample to deposit H2S, HS⁻ and S²â», as well as plasma protein, then used NaOH to re-dissolve plasma protein. ZnS deposition was re-dissolved by the addition of N, N-dimethyl-p-phenylenediamine, and the remnant protein was deposited by trichloroacetic acid. After centrifugation, ferriammonium sulfate was added to the supernatant fluid to generate methylene blue, which was analyzed by spectrophotometer at 665 nm. Using the present method, we found that most ions including sulfate and thiosulfate did not affect detection of H2S concentration, but albumin (physiological concentration) reduced the detection value, which suggested the binding of serum albumin and a certain amount of H2S. The relative recovery ratio of present method is 81.9%, which implies that the method is relative accurate for the determination of H2S concentration in plasma or serum. H2S levels of frozen plasma samples from 65 healthy volunteers detected by the present method were (13.93 ± 4.98) µmol/L. There was no obvious difference between the detection values of fresh and frozen samples from the same SD rats. These results suggest the modified methylene blue assay is stable, sensitive, convenient and high-throughput. The method can be used to analyze the circulatory H2S in clinical and basic research.

[Adrenomedullin alleviates collagen accumulation in pulmonary arteries of rats with hypoxic pulmonary hypertension].

OBJECTIVE: To observe the effect of adrenomedullin (ADM) on the pulmonary vascular collagen metabolism in hypoxic rats in order to study the effect of ADM on chronic hypoxic pulmonary vascular structural remodeling and its possible mechanism. METHODS: Nineteen male Wistar rats were randomly divided into three groups: normal control (n=6), hypoxia (n=7) and ADM-treated hypoxia (n=6). ADM was subcutaneously administered into rats of the ADM-treated hypoxia group by mini-osmotic pump (300 ng/h) for two weeks. After two weeks of hypoxic challenge, mean pulmonary arterial pressure (mPAP) was evaluated using a right cardiac catheterization procedure. The ratio of right ventricular mass to left ventricular plus septal mass[RV/ (LV+S)] was measured. The changes of pulmonary vascular microstructure were observed. Meanwhile, the expression levels of collagen I, collagen III and transforming growth factor (TGF)-ß in pulmonary arteries were detected by immunohistochemical assay. RESULTS: mPAP and RV/(LV+S) increased significantly in the hypoxia group compared with normal controls (P<0.01). The muscularization of small pulmonary vessels and the relative medial thickness of pulmonary arteries increased obviously in the hypoxia group compared with those in the normal control group (P<0.01). Meanwhile, the expression levels of collagen I, collagen III and TGF-ß of pulmonary arteries in the hypoxia group increased markedly compared with those in the normal control group. However, mPAP and RV/(LV+S) were significantly reduced in the ADM-treated hypoxia group compared with those in the hypoxia group (P<0.01). ADM ameliorated pulmonary vascular structural remodeling of hypoxic rats, with a decrease in the expression of collagen I, collagen III and TGF-ß of pulmonary arteries. CONCLUSIONS: ADM might play a regulatory role in the development of hypoxic pulmonary hypertension and hypoxic pulmonary vascular remodeling, through inhibiting the expression of TGF-ß and alleviating the collagen accumulation of pulmonary arteries.

Effect of sulfur dioxide preconditioning on rat myocardial ischemia/reperfusion injury by inducing endoplasmic reticulum stress.

Sulfur dioxide has recently been found to be produced endogenously in the cardiovascular system and have important positive biological effects. However, it is unknown whether sulfur dioxide preconditioning has a protective effect on rat myocardial ischemia/reperfusion (I/R) injury and whether this process involves endoplasmic reticulum stress (ERS). In this study, we showed that preconditioning with sulfur dioxide 10 min before ischemia (with a low concentration of sulfur dioxide of 1-10 µmol/kg) could reduce myocardial infarct size and plasma activities of lactate dehydrogenase and creatine kinase in rats with I/R in vivo. Sulfur dioxide preconditioning also reduced myocardium apoptosis induced by I/R. In addition, sulfur dioxide preconditioning increased cardiac function in vitro. Sulfur dioxide preconditioning induced expression of myocardial glucose-regulated protein 78 (GRP78) and phosphorylated eukaryotic initiation of the factor 2α-subunit (p-eIF2α) prior to myocardial I/R but suppressed expression of myocardial GRP78, C/EBP homologous protein, and p-eIF2α during myocardial I/R, in association with improved myocardial injury in vivo and in vitro. Pretreatment with dithiothreitol, an ERS stimulator mimicked the above cardioprotective effect. However, pretreatment with the ERS inhibitor 4-phenylbutyrate reversed the cardioprotection provided by sulfur dioxide preconditioning. These data indicated that sulfur dioxide preconditioning reduced I/R-induced myocardial injury in vivo and in vitro, and that augmenting ERS by sulfur dioxide preconditioning prior to I/R contributed to protection against myocardial I/R injury.

The vasorelaxing effect of hydrogen sulfide on isolated rat aortic rings versus pulmonary artery rings.

AIM: To compare the vasorelaxing effects of hydrogen sulfide (H(2)S) on isolated aortic and pulmonary artery rings and to determine their action mechanisms. METHODS: H(2)S-induced vasorelaxation of isolated rat aortic versus pulmonary artery rings under 95% O(2) and 5% CO(2) was analyzed. The expression of cystathinonine gamma-lyase (CSE), cystathionine beta synthase (CBS), 3-mercaptopyruvate sulfurtransferase (3MST), SUR2B and Kir6.1 was examined. RESULTS: NaHS caused vasorelaxation of rat aortic and pulmonary artery rings in a dose-dependent manner. NaHS dilated aortic rings to a greater extent (16.4%, 38.4%, 64.1%, 84.3%, and 95.9% at concentrations of 50, 100, 200, 500, and 1000 µmol/L, respectively) than pulmonary artery rings (10.1%, 22.2%, 50.6%, 73.6%, and 84.6% at concentrations of 50, 100, 200, 500 and 1000 µmol/L, respectively). The EC(50) of the vasorelaxant effect for aortic rings was 152.17 µmol/L, whereas the EC(50) for pulmonary artery rings was 233.65 µmol/L. The vasorelaxing effect of H(2)S was markedly blocked b y cellular and mitochondrial membrane K(ATP) channel blockers in aortic rings (P<0.01). In contrast, only the cellular membrane K(ATP) channel blocker inhibited H(2)S-induced vasorelaxation in pulmonary artery rings. SUR2B mRNA and protein expression was higher in aortic rings than in pulmonary artery rings. Cystathinonine gamma-lyase (CSE) but not cystathionine beta synthase (CBS) expression in aortic rings was higher than in pulmonary artery rings. 3-Mercapto pyruvate sulfurtransferase (3MST) mRNA was lower in aortic rings than in pulmonary artery rings. CONCLUSION: The vasorelaxing effect of H(2)S on isolated aortic rings was more pronounced than the effect on pulmonary artery rings at specific concentrations, which might be associated with increased expression of the K(ATP) channel subunit SUR2B.

Sulfur dioxide derivatives depress L-type calcium channel in rat cardiomyocytes.

1. Sulfur dioxide (SO(2) ) has recently been found to have various biological effects on the cardiovascular system. The present study was designed to explore the effects of SO(2) derivatives on the L-type calcium current (I (Ca, L) ) in isolated rat ventricular cardiomyocytes. 2. A Langendorf system was used to dissociate single ventricular cells. SO(2) derivatives from 5 to 1000 µmol/L were incubated with cardiomyocytes. The whole-cell patch-clamp technique was used to record I (Ca, L) . The effect of SO(2) derivatives on intracellular calcium concentration ([Ca(2+) ](i) ) was detected by confocal microscopy. 3. Concentrations of 5 or 10 µmol/L SO(2) derivatives could not change I (Ca, L) evoked by a single pulse from -40 to 0 mV for 200 ms in rat ventricular cardiomyocytes; however, 50, 100, 500 or 1000 µmol/L SO(2) derivatives could depress the peak amplitudes of calcium currents in 6 min, and the I (Ca, L) was attenuated by 13.19%, 16.59%, 21.23% and 24.72%, respectively, as compared with corresponding controls (P < 0.05). The 50, 100, 500 or 1000 µmol/L SO(2) derivatives also depressed the peak I-V curves, without altering the reversal potential and the voltage dependence of the peak I (Ca, L) . Therefore, 1000 µmol/L SO(2) derivatives could reduce [Ca(2+) ](i) in cardiomyocytes. 4. The results of the present study suggest that SO(2) derivatives can depress I (Ca, L) in cardiomyocytes, which might have a protective effect in cardiovascular diseases.

[Change and significance in the levels of plasma urotensin II and catestatin in children with postural orthostatic tachycardia syndrome].

OBJECTIVE: To explore possible mechanisms by analyzing cardiovascular bioactive peptides levels in children with postural orthostatic tachycardia syndrome (POTS). METHODS: Forty-six children diagnosed as POTS (POTS group, aged 12.1±2.8 years) and 20 healthy children (control group, aged 11.5±3.6 years) were enrolled as controls in this clinical controlled study. Two kinds of cardiovascular bioactive peptides named urotensin II (UII) and catestatin (Cs) were measured by using enzyme immunoassay. The comparisons between the two groups were made by independent t test or non-parametric test. Correlation analyses between plasma levels of bioactive peptides and changes in heart rate during standing test or head-up tilt test (HUT) were conducted using bivariate correlations. RESULTS: The plasma UII levels were significantly lower in POTS group as compared with those of controls [0.41 (0.27, 0.85) µg/L in POTS group vs. 0.46 (0.35, 1.41) µg/L in control group, P<0.05]. The plasma UII level was negatively correlated with the increase in heart rate during standing test or head-up tilt test (correlation coefficient-0.363, P<0.05). No difference was found in plasma Cs levels between the two groups [ 0.48 (0.20, 1.91) µg/L in POTS group vs. 0.48 (0.20, 1.91) µg/L in control group, P>0.05]. CONCLUSION: POTS children had low levels of plasma UII, and disturbance of vascular tone regulation might play a role in POTS of children.