To investigate the effects of metallothionein (MT) on isolated rat heart, 16 Wistar rats were randomly divided into 2 groups. In control group (group C), distilled water was injected intraperitoneally and 24 h later isolated hearts were perfused with Langendorff and stored at 4 degrees C for 3 h with histidine-tryptophan-ketoglutarate (HTK) solutions, and then isolated hearts were perfused for 2 h by Langendorff. In experimental group (group E), 3.6% ZnSO(4) was injected intraperitoneally, 24 h later isolated hearts were perfused by Langendorff and stored at 4 degrees C for 3 h with HTK solutions, and then the isolated hearts were perfused for 2 h with Langendorff. MT content, the recovery of hemodynamics, myocardial water content (MWC), lactate dehydrogenase (LDH) and creatine kinase (CK) leakage, adenosine triphosphate (ATP) and malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, myocardial cell Ca(2+) content, Ca(2+)-ATPase activity of mitochondria ([Ca(2+)-ATPase](m)) and its Ca(2+) content ([Ca(2+)](m)), synthesizing ATP activity of mitochondria ([ATP](m)), and the ultrastructure of cells were examined. There were a significant increase in group E in hemodynamic recovery, ATP content, SOD activity, [Ca(2+)-ATPase](m) activity, [ATP](m) activity, and substantial reduction in MWC, LDH and CK leakage, MDA content, myocardial cell Ca(2+) content, [Ca(2+)](m) content, and the ultrastructural injury were obviously milder than that of group C. This study demonstrated that MT has protective effects on isolated rat heart.
Cardiotonic Agents/*pharmacology ; Creatine Kinase/*metabolism ; L-Lactate Dehydrogenase/metabolism ; Metallothionein/biosynthesis ; Metallothionein/*pharmacology ; Myocardium/*metabolism ; Myocardium/ultrastructure ; Random Allocation ; Rats, Wistar ; Superoxide Dismutase/metabolism ; Zinc Sulfate/pharmacology

Cadmium ; pharmacology ; Cells, Cultured ; Heat-Shock Proteins ; biosynthesis ; Humans ; Metallothionein ; biosynthesis ; Ubiquitin ; biosynthesis

The effect of dexamethasone (10(-5)M) and epinephrine (10(-6)M) on the biosynthesis of metallothionein (MT) in the perfused rat liver was investigated. MT synthesis was determined by measuring the incorporation of 14C-L-aspartic acid into liver MT fraction after the perfusion for five hours of isolated liver by artificial blood containing 14C-L-U-aspartic acid (0.2uci) with dexamethasone or epinephrine. MT was isolated by Sephadex G-75 column chromatography and DEAE Sephadex column chromatography. Incorporation of radioactive 14C into the MT fraction of perfused liver cytosol (9.0grams of liver) from dexamethasone treated, epinephrine treated and control groups were, respective1y, 0.72, 0.34 and 0.33% of total radioactivity infused. Total protein content in the MT fraction of liver perfused with dexamethasone and epinephrine were 0.80, 0.64mg/g liver compared to 0.52mg/g liver in the control. MT, a protein having a high content of cystein and metals is synthesized in the perfused rat liver and its induction is stimulated by dexamethasone, while epinephrine increased the accumulation of Zn in the MT fraction of the perfused rat liver. The present experiment confirms that MT synthesis and degradation are somewhat regulated by glucocorticoid hormone and epinephrine.
Animal ; Dexamethasone/pharmacology* ; Epinephrine/pharmacology* ; Female ; In Vitro ; Liver/drug effects ; Liver/metabolism* ; Metalloproteins/metabolism* ; Metallothionein/metabolism* ; Perfusion ; Rats ; Zinc/metabolism

Homocysteine ; pharmacology ; Human Umbilical Vein Endothelial Cells ; drug effects ; metabolism ; Humans ; Lipid Peroxidation ; drug effects ; Metallothionein ; pharmacology

OBJECTIVETo explore the effects of cadmium on zinc metabolism and its function and the protective effects of pre-supplement zinc to it.

METHODSNS or different doses of CdCl(2) were injected to pregnant dams intraperitoneally at the 7th, 10th and 13th day of gestation respectively. At the 21st pregnant day embryos were taken out from the pregnant rats. Another rats of pre-supplement zinc or no pre-supplement zinc group were injected different doses of CdCl(2) or NS intraperitoneally after 6 days. After 24 hours the rats were killed. The contents of Cd, Zn and relative biomarkers of effect of liver, brain or serum were detected in both embryos and adult rats.

RESULTSCompared with control group, the contents of T-AOC and Ach were significantly reduced in the Cd treatment group in the embryonic brains, the activity of AKP in the embryonic liver tissues was decreased, and The Cd content was increased significantly in embryonic liver and was negatively correlated with the Zinc content in the embryonic brain. There were no differences in the activities of SOD and AKP and the contents of Cd and MDA between pre-supplement Zn control group and no supplement Zn control group, but higher content of Zn in liver and serum in the former. Compared with no supplement Zn control group, there were higher contents of Cd in liver and serum, Zn and MDA in liver, lower activities of SOD in liver and AKP in liver and serum, and lower content of Zn in serum in the Cd treatment groups. Pre-supplement Zn significantly increase the content of Zn and the activities of SOD in liver and AKP in serum, decrease the content of MDA in liver and Cd in serum resulted by Cd treatment only. The content of Zn and the activity of AKP in serum and the activities of SOD and AKP in liver were negatively correlated with the content of Cd in corresponding tissue significantly.

CONCLUSIONCadmium can enter embryo and enter brain by permeating the brain-blood barrier during the embryonic period. The decrease of AKP activity, some neural transmitter and capacity of anti-lipid peroxidation that are related with Zn in embryos are caused when the pregnant rats are administered with cadmium. Cd can inhibits the activities of AKP and SOD in liver, and the activity of AKP in serum respectively, and increase the content of MDA in liver dose-dependently. The effects induced by cadmium are related with zinc abnormal distribution. Pre-supplement zinc to rats can antagonize these effects in different degree.

Animals ; Cadmium ; toxicity ; Female ; Liver ; metabolism ; Male ; Maternal Exposure ; Metallothionein ; metabolism ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Zinc ; metabolism ; pharmacology

AIMTo evaluate the effects of different doses of zinc on the expression of metallothionein isoforms in stressed hippocampal neurons in vitro.

METHODSThe cell stress model was developed by corticosterone. The cultured hippocampal neurons were assigned to seven groups as follows: control group, zinc deficiency group, and their corresponding stressed groups, as well as three different levels of zinc complementarity groups.

RESULTSIn zinc deficiency group, the expressions of metallothionein and MT-1 mRNA, MT-3 mRNA were downregulated. On the other hand, inductions of metallothionein and it's mRNAs in stressed zinc complementarity group were increased. In addition, the levels of supernatant IL-6 and NO were increased clearly in zinc deficiency group and corticosterone stressed groups.

CONCLUSIONOur results suggest that zinc deficiency may decrease while zinc complementarity increase the expressions of metallothioneins and MT-1 mRNA, MT-3 mRNA in stressed hippocampal neurons in vitro.

Animals ; Animals, Newborn ; Hippocampus ; cytology ; metabolism ; In Vitro Techniques ; Metallothionein ; metabolism ; Neurons ; metabolism ; RNA, Messenger ; Rats ; Zinc ; pharmacology

OBJECTIVETo study the possible intervention of isoflavones in cytotoxicity induced by cadmium in vascular endothelial cells.

METHODSAn ECV 304 cell line derived from human umbilical vein endothelial cells was adopted. Genistein/daidzein was added prior to or simultaneously with CdCl2, cell viability was determined by MTT assay, and metallothionein mRNA expression was monitored by RT-PCR method.

RESULTSCell viability was higher in isoflavone and CdCl2 co-treated groups than that in CdCl2 treated group, with CdCl2 concentration at 10, 20, 40, and 80 micromol/L, respectively. However this increase was not observed in the group treated with CdCl2 at a concentration of 60 micromol/L. Isoflavones (10(-10) mol/L to 10(-5) mol/L) were added 24 h before cells were challenged with 80 micromol/L CdCl2 for 24 h or simultaneously with 80 micromol/L CdCl2. Genistein increased cell viability only at 10(-5) mol/L, while daidzein caused a dose-dependent increase from 10(-10) mol/L to 10(-5) mol/L in co-treatment with CdCl2. In pre-treatment, genistein (10(-7) to 10(-5) mol/L) increased cell viability whereas only 10(-5) mol/L of daidzein exerted protection. Apparent protection could be found when the cells were pre-treated with 10(-5) mol/L isoflavones for over 12 h, whereas 24 h incubation was required in such a co-treatment, with the exception of daidzein that had a significant protection in only 3 h. Isoflavones (10(-6) mol/L) incubated for 3 h to 24 h, increased MT IIA and MT IF mRNA expression, but the induction could not last for more than 24 h. Co-treatment with isoflavones could induce an additional induction of MT IIA mRNA expression in cells exposed to cadmium. However, the additional induction of MT IIA and MT IF mRNA was not seen when pre-treatment was carried out with isoflavones, with the exception of an increase in MT IIA mRNA expression in the daidzein pre-treated group.

CONCLUSIONGenistein/daidzein could reverse the cytotoxicity of cadmium either in pre-treatment or in co-treatment. The protection is the strongest in 10(-5) mol/L of isoflavones with a dose-dependent pattern. There are differences between genistein and daidzein in their protective effects. Whether the protection of isoflavones is related to their capacity of inducing MT mRNA expression remains to be elucidated.

Cadmium ; toxicity ; Cell Line ; Cell Survival ; drug effects ; Endothelial Cells ; drug effects ; metabolism ; Genistein ; pharmacology ; Humans ; Isoflavones ; pharmacology ; Metallothionein ; genetics ; metabolism ; Protective Agents ; pharmacology ; RNA, Messenger ; metabolism

Metallothioneins (MT), small molecular weight metal binding proteins are known to play an important protective role against heavy metal toxicity, either as antioxidants or pre-oxidants. However, the mode of metabolic fate of MTs in various metal complexes is not clearly understood. This study was carried out to better understand the mode of selective turnover rate of various form of MT in complexes with different metals. The degradation of in vitro translated mouse 35S-cysteine-MT was examined in lysosomal or cytosolic fractions from mouse liver by gel electrophoresis and autoradiography. Overnight incubations of MT showed extensive proteolysis in the lysosomal fraction but not in cytosolic fractions. However, Cu2+-MT was found to be stable under the same experimental condition. In contrast, Zn did not interfere with MT degradation. These results suggest that lysosomes are chiefly responsible for MT removal and appears to be selective on the metals involved in the MT complex. In vitro, translated, radiolabeled MT provides a suitable substrate for investigating the characteristics of MT degradation.
Animal ; Copper/*metabolism/pharmacology ; Ions ; Liver/drug effects/*metabolism ; Lysosomes/metabolism ; Metallothionein/drug effects/*metabolism ; Mice ; Sulfur Radioisotopes ; Support, Non-U.S. Gov't ; Zinc/*metabolism/pharmacology

OBJECTIVE[corrected] To assess the effects of metallothionein on myocyte apoptosis and energy supply of isolated rabbit heart muscle during perfusion with ropivacaine..

METHODSSixty New Zealand white male rabbits were randomized into 3 equal groups. In group I, the rabbits received a intreaperitioneal injection of distilled water 24 h before isolation of the heart with perfusion by Langendoff model; in group II, distilled water was injected intreaperitioneally, and 24 h later the heart was isolated and perfused with Langendoff model and ropivacaine; in group III, 3.6% ZnSO(4) was injected intreaperitioneally and the isolated heart was perfused with Langendoff model and ropivacaine. The myocardial metallothionein content, myocyte apoptosis, and myocardial ATP, ADP and AMP content were detected.

RESULTSThe myocardial metallothionein content was significantly higher in group III than in the other two groups; the percent of myocyte apoptosis was the highest in group II, and was significantly higher in group III than in group I. The myocardial content of ATP was the highest in group I, and was significantly higher in group III than in group II.

CONCLUSIONMetallothionein can significantly inhibit myocyte apoptosis and alleviate energy supply disorder induced by ropivacaine.

Amides ; pharmacology ; Animals ; Apoptosis ; drug effects ; Energy Metabolism ; drug effects ; In Vitro Techniques ; Male ; Metallothionein ; pharmacology ; Myocardium ; cytology ; metabolism ; Myocytes, Cardiac ; cytology ; metabolism ; Perfusion ; Rabbits

OBJECTIVETo investigate the feasibility of metallothionein (MT) gene expression level in human peripheral blood lymphocytes (HPBLs) as a biomarker in cadmium exposure.

METHODSThe MT gene expression level in HPBLs of workers exposed to cadmium was examined using RT-PCR technique, and the exposure assessment and effect assessment were conducted in exposed workers.

RESULTSThe basal MT-1A, IE, IF, IX and MT-2A expression level in workers exposed to cadmium were significantly higher than those in the control group (P < 0.05). The basal MT-1A, IE, IF, IX and MT-2A expression level would be significantly increased with the increase of the blood cadmium (BCd) level (P < 0.05). There was a trend of increase for the mRNA expression of the basal MT-1A, 1E, IF, IX, MT-2A, especially for the mRNA expression of MT-1A and MT-2A (P < 0.05) with the increase of the level of the urine cadmium (UCd). There was a good dose-response relationship between basal MT-1A expression and UCd. The basal MT-1A, IE, IF, IX and MT-2A expression level were significantly correlated with BCd (P < 0.05) while the basal MT-1A, IF and MT-2A expression level were significantly correlated with UCd (P < 0.05). There were dose-effect relationships of BCd to the basal MT-1E, MT-1F, MT-1X and MT-2X expression level respectively and there were also dose-effect relationships of UCd, beta(2)-MG and the urine metallothionein to the basal MT-1A expression.

CONCLUSIONThe expression of the MT gene isoforms in HPBLs can serve as the biomarker for the cadmium exposure and MT-1A can also serve as the effective biomarkers for the cadmium-induced renal toxicity.

Adult ; Biomarkers ; metabolism ; Cadmium ; metabolism ; pharmacology ; Dose-Response Relationship, Drug ; Female ; Gene Expression ; Humans ; Lymphocytes ; metabolism ; Male ; Metallothionein ; biosynthesis ; genetics ; Occupational Exposure ; Protein Isoforms ; biosynthesis ; RNA, Messenger ; genetics