OBJECTIVETo explore the impact of sulfur dioxide (SO(2)) on hydrogen sulfide (H(2)S)/cystathionine-γ-lyase (CSE) and H(2)S/mercaptopyruvate sulfurtransferase (MPST) pathways in the pathogenesis of hypoxic pulmonary hypertension.

METHODSThirty-two male Wistar rats were randomly divided into four groups: control group (n = 8), hypoxic group (n = 8), hypoxic + SO(2) group (n = 8) and hypoxic + hydroxamate (HDX) group (n = 8). After 21 days of experiment, the concentration and production of H(2)S in lung tissues were measured respectively for each rat. The protein expression of CSE and MPST in intima and media of small pulmonary arteries in rats was detected with immunohistochemical method.

RESULTSCompared with control group, the mean pulmonary artery pressure (mPAP) in rats of hypoxic group was increased significantly [(33.38 ± 6.32) mm Hg vs. (16.74 ± 3.81) mm Hg, P < 0.01]. Compared with hypoxic group, the mPAP in rats of hypoxic + SO(2) group was decreased significantly [(29.65 ± 2.53) mm Hg vs. (33.38 ± 6.32) mm Hg, P < 0.01]. However, compared with hypoxic group, the mPAP in rats of hypoxic + HDX group was increased significantly [(39.44 ± 6.26) mm Hg vs. (33.38 ± 6.32) mm Hg, P < 0.01]. Compared with control group, the concentration [(2.02 ± 0.43) µmol/g vs. (3.11 ± 0.42) µmol/g, P < 0.01] and production [(19.64 ± 3.48) nmol/(g·min)vs. (28.20 ± 5.95) nmol/(g·min), P < 0.05] of H(2)S were decreased significantly in rats of hypoxic group, respectively. When treated with SO(2), hypoxic rats showed an increased concentration [(2.73 ± 0.20) µmol/g vs. (2.02 ± 0.43) µmol/g, P < 0.01] and production [(26.24 ± 1.92) nmol/(g·min) vs. (19.64 ± 3.48) nmol/(g·min), P < 0.01] of H(2)S in lung tissue compared with those without receiving SO(2) treatment. When treated with HDX, hypoxic rats showed a significant decrease in concentration [(1.64 ± 0.23) µmol/g vs. (2.02 ± 0.43) µmol/g, P < 0.05] and production [(13.94 ± 3.63) nmol/(g·min) vs. (19.64 ± 3.48) nmol/(g·min), P < 0.05] of H(2)S in lung tissue compared with those without receiving HDX treatment. As for the expression of CSE in small pulmonary arteries (SPAs), compared with control group, the expression of CSE in intima [(0.31 ± 0.02) vs. (0.36 ± 0.01), P < 0.01] and media [(0.27 ± 0.01) vs. (0.30 ± 0.01), P < 0.01] in rats of hypoxic group was decreased significantly. While compared with hypoxic group, the expression of CSE in intima [(0.35 ± 0.02) vs. (0.31 ± 0.02), P < 0.01] in SPAs of hypoxic + SO(2) group was increased significantly. With HDX treatment, the expression of CSE in intima [(0.26 ± 0.01) vs. (0.31 ± 0.02), P < 0.01] in SPAs of hypoxic group was lower than that without HDX treatment. As for the expression of MPST in SPAs, compared with hypoxic group, the expression of MPST in media [(0.32 ± 0.02) vs. (0.29 ± 0.01), P < 0.01] in SPAs of hypoxic + SO(2) group was increased significantly.

CONCLUSIONSO(2) might upregulate H(2)S/CSE and H(2)S/MPST pathways in pulmonary arteries of hypoxic rats.

Animals ; Cystathionine gamma-Lyase ; metabolism ; Hydrogen Sulfide ; metabolism ; Hypertension, Pulmonary ; enzymology ; physiopathology ; Hypoxia ; metabolism ; physiopathology ; Male ; Pulmonary Artery ; metabolism ; physiopathology ; Rats ; Rats, Wistar ; Sulfur Dioxide ; pharmacology ; Sulfurtransferases ; metabolism

BACKGROUNDEndogenous hydrogen sulfide is a new neuromodulator which takes part in the regulation of central nervous system physiology and diseases. Whether endogenous hydrogen sulfide in the central nervous system regulates cardiovascular activity is not known. In the present study, we observed the hemodynamic changes of hydrogen sulfide or its precursor by intracerebroventricular injection, and investigate the possible roles of endogenous digitalis like factors and sympathetic activity in the regulation.

METHODSNinety-four Sprague-Dawley rats underwent a right cerebroventricular puncture, then the hydrogen sulfide saturation buffer or its precursor injected by intrcerebroventricular catheter. A heperin-filled catheter was inserted into the right femoral artery or into the left ventricle, and changes of blood pressure or cardiac function recorded by a Powerlab/4S instrument. Phentolamine or metoprolol were pre-injected to observe the possible role in autonomic nerve activity. After rats were sacrificed, plasma was collected and endogenous digitalis-like factors were measured with a commercial radioimmunoassay kit. The aortic, cardiac sarcolemmal vesicles were isolated and the activity of Na(+)-K(+)-ATPase was measured as ouabain-sensitive ATP hydrolysis under maximal velocity conditions by measuring the release of inorganic phosphate from ATP. Unpaired Student's t test for two groups or analysis of variances (ANOVA) for multiple groups were used to compare the differences of the changes.

RESULTSIntracerebroventricular injection of hydrogen sulfide induced a transient hypotension, then dramatic hypertenive effects in a dose-dependent manner. Bolus injection of L-cysteine or beta- mercaptopyruvate also increased mean arterial pressure (P < 0.01), whereas hydroxylamine-a cystathionine beta synthase inhibitor decreased the arterial pressure (P < 0.01). Hydrogen sulfide and L-cysteine increased mean arterial pressure, left ventricular develop pressure and left-ventricle maximal rate of systolic and diastolic pressure; these functions were decreased by hydroxylamine (P < 0.01). Glibenclamide (a K(ATP) channel blocker) blocked the transient hypotensive effect, phentolamine (an alpha-adrenergic receptor blocker) blocked the hypertensive effect, and metoprolol (a selective beta 1 receptor blocker) blocked the positive inoptropic effect of central nervous system hydrogen sulfide. The endogenous digitalis-like factors in plasma were elevated (P < 0.01) after treatment with L-cysteine, association with decreasing Na(+)-K(+)-ATPase activity in cardiac or aortic sarcolemmal vesicles (P < 0.01). Hydroxylamine injection reduced the endogenous digitalis-like factors level in plasma association with increasing Na(+)-K(+)-ATPase activity in cardiac and aortic sarcolemmal vesicles.

CONCLUSIONCentral nervous system endogenous hydrogen sulfide upregulated mean arterial pressure and cardiac systolic function by activation of sympathetic nerves or release of endogenous digitalis-like factors.

Animals ; Blotting, Western ; Cardenolides ; metabolism ; Central Nervous System ; drug effects ; metabolism ; Cystathionine beta-Synthase ; metabolism ; Cysteine ; analogs & derivatives ; pharmacology ; Hemodynamics ; drug effects ; Hydrogen Sulfide ; metabolism ; pharmacology ; Male ; Radioimmunoassay ; Rats ; Rats, Sprague-Dawley ; Saponins ; metabolism ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Sulfurtransferases ; metabolism

We have investigated the effect of cholestasis on the hepatic thiosulfate sulfurtransferase (rhodanese) and UDP-glucuronosyltransferase (UDP-GT) activities in rats. Rhodanese activities in the liver cytosol, mitochondria and microsomal fractions as well as in the rat serum, and UDP-GT activity in the microsome have been investigated for a period of 42 days after common bile duct (CBD) ligation. The cytosolic rhodanese activity showed a significant decrease between the first through the 42nd day, and the mitochondrial activity showed a significant decrease between the 7th through the 42nd day after CBD ligation compared to the activities from the sham operated control, respectively. In the case of microsomal preparation, both rhodanese and UDP-GT also showed significant decrease in their activities after the ligation for the former enzyme between the 14th and the 42nd days, and for the latter enzyme between the third and 42nd days, respectively. On the other hand, the serum rhodanese activity increased markedly soon after the ligation, exhibiting the peak activity after 1 day of CBD ligation with about 4.6-fold increment. The activity subsequently decreased gradually reaching to the control level at the 42nd day post-ligation. Enzyme kinetic parameters of hepatic rhodanese and UDP-GT were analyzed using sodium thiosulfate and p-nitrophenol as substrates, respectively, with the preparations from the 28th day post-ligation. The results indicated that although the K-m values of these enzymes were about the same as the sham-operated control, the V-max values of the both enzymes decreased significantly. These results, therefore, suggest that the biosynthesis of rhodanese and UDP-GT have been reduced in response to cholestasis, and that the elevation of rhodanese activity in the serum is most likely due to leakage from the liver subsequent to CBD ligation.
Animals ; Cholestasis ; Common Bile Duct* ; Cytosol ; Hand ; Ligation* ; Liver* ; Microsomes ; Mitochondria ; Rats* ; Sodium ; Thiosulfate Sulfurtransferase*

PURPOSE: To Study the possible mechanisms of change of thiosulfate sulfurtransferase (TST) activity in cholestatic rat liver and serum. METHODS: Rats were divided into seven groups: those receiving a sham operation (Sham group), with a bile duct obstruction (BDO) alone (BDO group), with a BDO plus taurocholic acid (TCA) injection (BDO plus TCA group), with a BDO plus tauroursodeoxycholic acid (TUDCA) injection (BDO plus TUDCA group), a choledocho-caval shunt (CCS) operation (CCS groups), a CCS operation plus TCA injection (CCS plus TCA group) and a CCS operation plus TUDCA injection (CCS plus TUDCA group). The TST activities in the serum and in the hepatic subcellular fractions isolated from above experimental rats were determined. The Km and Vmax values of this hepatic enzyme were measured. RESULTS: The liver cytosolic, mitochondrial and microsomal TSTs activities, as well as the TST Vmax values were found to be significantly decreased in the BDO plus TCA and BDO groups compared to the control group. The activity and Vmax value of the liver cytosolic TST were also found to be significantly decreased in the CCS plus TCA group. Conversely, there was no variation in the Km values of the hepatic enzymes in any of the above experimental groups. The serum TST activities in the CCS plus TCA and BDO plus TCA groups, were significantly increased compared with the control, CCS and BDO groups. However, the serum and hepatic enzyme activities were unchanged in both the CCS plus TUDCA and BDO plus TUDCA groups. CONCLUSION: The above results indicate that TCA represses the biosynthesis of TST in the liver. Also, the elevated TST activity in the serum is most likely due to an increase in the permeability of hepatocytes membrane upon TCA mediated liver cell necrosis.
Administration, Intravenous* ; Animals ; Cholestasis ; Cytosol ; Hepatocytes ; Liver* ; Membranes ; Necrosis ; Permeability ; Rats* ; Subcellular Fractions ; Taurocholic Acid* ; Thiosulfate Sulfurtransferase*

PURPOSE: To Study the possible mechanisms of change of thiosulfate sulfurtransferase (TST) activity in cholestatic rat liver and serum. METHODS: Rats were divided into seven groups: those receiving a sham operation (Sham group), with a bile duct obstruction (BDO) alone (BDO group), with a BDO plus taurocholic acid (TCA) injection (BDO plus TCA group), with a BDO plus tauroursodeoxycholic acid (TUDCA) injection (BDO plus TUDCA group), a choledocho-caval shunt (CCS) operation (CCS groups), a CCS operation plus TCA injection (CCS plus TCA group) and a CCS operation plus TUDCA injection (CCS plus TUDCA group). The TST activities in the serum and in the hepatic subcellular fractions isolated from above experimental rats were determined. The Km and Vmax values of this hepatic enzyme were measured. RESULTS: The liver cytosolic, mitochondrial and microsomal TSTs activities, as well as the TST Vmax values were found to be significantly decreased in the BDO plus TCA and BDO groups compared to the control group. The activity and Vmax value of the liver cytosolic TST were also found to be significantly decreased in the CCS plus TCA group. Conversely, there was no variation in the Km values of the hepatic enzymes in any of the above experimental groups. The serum TST activities in the CCS plus TCA and BDO plus TCA groups, were significantly increased compared with the control, CCS and BDO groups. However, the serum and hepatic enzyme activities were unchanged in both the CCS plus TUDCA and BDO plus TUDCA groups. CONCLUSION: The above results indicate that TCA represses the biosynthesis of TST in the liver. Also, the elevated TST activity in the serum is most likely due to an increase in the permeability of hepatocytes membrane upon TCA mediated liver cell necrosis.
Administration, Intravenous* ; Animals ; Cholestasis ; Cytosol ; Hepatocytes ; Liver* ; Membranes ; Necrosis ; Permeability ; Rats* ; Subcellular Fractions ; Taurocholic Acid* ; Thiosulfate Sulfurtransferase*

Cyanide poisoning can occur from industrial disasters, smoke inhalation from fire, food, and multiple other sources. Cyanide inhibits mitochondrial oxidative phosphorylation by blocking mitochondrial cytochrome oxidase, which in turn results in anaerobic metabolism and depletion of adenosine triphosphate in cells. Rapid administration of antidote is crucial for life saving in severe cyanide poisoning. Multiple antidotes are available for cyanide poisoning. The action mechanism of cyanide antidotes include formation of methemoglobin, production of less or no toxic complex, and sulfane sulfur supplementation. At present, the available antidotes are amyl nitrite, sodium nitrite, sodium thiosulfate, hydroxocobalamin, 4-dimethylaminophenol, and dicobalt edetate. Amyl nitrite, sodium nitrite, and 4-dimethylaminophenol induce the formation of methemoglobin. Sodium thiosulfate supplies the sulfane sulfur molecule to rhodanese, allowing formation of thiocyanate and regeneration of native enzymes. Hydroxocobalamin binds cyanide rapidly and irreversibly to form cyanocobalamin. Dicobalt edetate acts as a chelator of cyanide, forming a stable complex. Based on the best evidence available, a treatment regimen of 100% oxygen and hydroxocobalamin, with or without sodium thiosulfate, is recommended for cyanide poisoning. Amyl nitrite and sodium nitrite, which induce methemoglobin, should be avoided in victims of smoke inhalation because of serious adverse effects.
Adenosine Triphosphate ; Aminophenols ; Amyl Nitrite ; Antidotes* ; Disasters ; Edetic Acid ; Electron Transport Complex IV ; Equipment and Supplies ; Fires ; Hydroxocobalamin ; Inhalation ; Metabolism ; Methemoglobin ; Oxidative Phosphorylation ; Oxygen ; Poisoning ; Polyphosphates ; Regeneration ; Smoke ; Sodium ; Sodium Nitrite ; Sulfur ; Thiocyanates ; Thiosulfate Sulfurtransferase ; Thiosulfates ; Vitamin B 12