metallothionein and Hypertension

Topics: Aged; Aging; Animals; Arteries; Arteriosclerosis; C-Reactive Protein; Carotid Arteries; Elasticity; Humans; Hypertension; Metallothionein; Prevalence; Risk Factors; Vascular Diseases

A hypothesis is proposed admitting the participation of apometallothioneines (AMT) as a common link in the etiopathogenesis of hypertonic disease (HD) and some diseases with polygene heredity. The preconditions of the hypothesis are discussed (role of genetic disposition, external factors as salt, stress, tobacco smoking, alcohol, microelements--V and Cd and glucocorticoids in the origination of arterial hypertension). AMT homeostasis is discussed as well as the possible connection with the metabolism of Zn and Cu and Cu in organism. The chelating capacity of AMT makes it a potential regulatory protein, associated with the activity of Zn- and Cu-dependent enzymes and metalloenzymes. The mosaicism of pathology is explained with the genetic polymorphism of those enzymes (D beta H, MAO, etc), regardless of the common etiopathogenetic link. Some schemes are presented illustrating the hypothesis. The tendencies of the future studies are outlined in searching of direct proofs of the hypothesis.

Topics: Adrenal Cortex; Animals; Apoproteins; Blood Pressure; Copper; Disease Models, Animal; Disease Susceptibility; Genes; Genetic Diseases, Inborn; Glucocorticoids; Homeostasis; Humans; Hypertension; Menkes Kinky Hair Syndrome; Metallothionein; Terminology as Topic; Zinc

Cadmium has been shown to manifest its toxicity in human and animals by mainly accumulating in almost all of the organs and kidney is the main target organ where it is concentrated mainly in cortex. Environmental exposure of cadmium occurs via food, occupational industries, terrestrial and aquatic ecosystem. At molecular level, cadmium interferes with the utilization of essential metals e.g. Ca, Zn, Se, Cr and Fe and deficiencies of these essential metals including protein and vitamins, exaggerate cadmium toxicity, due to its increased absorption through the gut and greater retention in different organs as metallothionein (Cd-Mt). Cadmium transport, across the intestinal and renal brush border membrane vesicles, is carrier mediated and it competes with zinc and calcium. It has been postulated that cadmium shares the same transport system. Cadmium inhibits protein synthesis, carbohydrate metabolism and drug metabolizing enzymes in liver of animals. Chronic environmental exposure of cadmium produces hypertension in experimental animals. Functional changes accompanying cadmium nephropathy include low molecular weight proteinuria which is of tubular origin associated with excess excretion of proteins such as beta 2 microglobulin, metallothionein and high molecular weight proteinuria of glomerular origin (excretion of proteins such as albumin IgG, transferrin etc.). Recent data has shown that metallothionein is more nephrotoxic to animals. Cadmium is also toxic to central nervous system. It causes an alterations of cellular functions in lungs. Cadmium affects both humoral and cell mediated immune response in animals. Cadmium induces metallothionein in liver and kidney but under certain nutritional deficiencies like protein-calorie malnutrition and calcium deficiency, enhanced induction and greater accumulation of cadmium metallothionein has been observed.

Topics: Aging; Animals; Bone Diseases; Cadmium; Calcium; Central Nervous System Diseases; Chromium; Copper; Dietary Proteins; Drug Interactions; Environmental Exposure; Female; Half-Life; Humans; Hypertension; Immunity; Intestinal Absorption; Intestinal Diseases; Iron; Kidney Diseases; Liver; Lung; Male; Metallothionein; Ovary; Selenium; Sex Factors; Testis; Tissue Distribution; Vitamins; Zinc

We investigated the effects of the neuroprotective drug cerebrolysin on the autoimmune parameters (FasL, Fas and metallotionein-1) in 20 newborns with perinatal ischemic CNS damage and 20 healthy newborns. The treatment with cerebrolysin in dosage of 0,1 ml per 1 kg of body mass, 10 injections every other day, resulted in the normalization (p<0,001) of the T-lymphocyte apoptosis (the increase of Fas and decrease of FasL) and activation of antioxidant protection through the increase of metallotionein-1 expression. The normalization of the autoimmunity was found to reduce edema and improve the circulation of the brain sites affected with ischemia.

Topics: Amino Acids; Antioxidants; Apoptosis; Autoantibodies; Fas Ligand Protein; Humans; Hypertension; Hypoxia-Ischemia, Brain; Infant, Newborn; Metallothionein; Nootropic Agents; Reverse Transcriptase Polymerase Chain Reaction; T-Lymphocytes

Hypertension is an independent risk factor for heart disease and is responsible for the increased cardiac morbidity and mortality. Oxidative stress plays a key role in hypertensive heart diseases although the precise mechanism remains unclear. This study was designed to examine the effect of cardiac-specific overexpression of metallothionein, a cysteine-rich antioxidant, on myocardial contractile and intracellular Ca(2+) anomalies in N(G)-nitro-l-arginine methyl ester (l-NAME)-induced experimental hypertension and the mechanism involved with a focus on autophagy. Our results revealed that l-NAME treatment (14 days) led to hypertension and myocardial anomalies evidenced by interstitial fibrosis, cardiomyocyte hypertrophy, increased LV end systolic and diastolic diameters (LVESD and LVEDD) along with suppressed fractional shortening. l-NAME compromised cardiomyocyte contractile and intracellular Ca(2+) properties manifested as depressed peak shortening, maximal velocity of shortening/relengthening, electrically-stimulated rise in intracellular Ca(2+), elevated baseline and peak intracellular Ca(2+). These l-NAME-induced histological and mechanical changes were attenuated or reconciled by metallothionein. Protein levels of autophagy markers LC3B and p62 were decreased and increased, respectively. Autophagy signaling molecules AMPK, TSC2 and ULK1 were inactivated while those of mTOR and p70s6K were activated by l-NAME, the effects of which were ablated by metallothionein. Autophagy induction mimicked whereas autophagy inhibition nullified the beneficial effect of metallothionein against l-NAME. These findings suggested that metallothionein protects against l-NAME-induced myocardial anomalies possibly through restoration of autophagy.

Topics: Animals; Autophagy; Calcium; Hypertension; Male; Metallothionein; Mice; Myocardial Contraction; Myocardium; NG-Nitroarginine Methyl Ester; Oxidative Stress; Reactive Oxygen Species; Sirolimus

Critical shortening of telomeres, likely associated with a considerable increase of senescent cells, can be observed in PBMC of individuals aged 80 and older. We investigated the relationship between critical telomere shortening and zinc status in healthy or hypertensive participants with or without cardiovascular disease in old and very old participants. Telomere shortening and accumulation of cells with short telomeres (percent of cells with short telomeres) in advancing age was evident in patients and healthy controls, but exacerbated in those patients aged 80 and older. Moreover, in very old patients, the accumulation of % CST may impair intracellular zinc homeostasis and metallothioneins expression, which itself is linked to an increased number of inflammatory agents, thereby suggesting the existence of a possible causal relationship between % CST and zinc homeostasis. The determination of % CST could be a more reliable means than the simple measure of telomere length as fundamental parameter in ageing to determine whether individuals are still able to respond to stress.

Topics: Aged; Aged, 80 and over; Aging; Body Mass Index; Cardiovascular Diseases; Case-Control Studies; Cellular Senescence; Down-Regulation; Homeostasis; Humans; Hypertension; Inflammation; Metallothionein; Middle Aged; Obesity; Risk Factors; Smoking; Surveys and Questionnaires; Telomere; Zinc

Because oxidative stress is involved in arterial hypertension, impairment of hepatic antioxidant defences could develop in the course of this disease. Metallothionein (MT), an antioxidant protein, is present in high rates in the liver. The aim of this study was to investigate the effect of a mineralocorticoid-salt treatment on blood pressure, hepatic antioxidant enzyme activities, and cardiac MT levels in transgenic MT null mice compared with control mice to further clarify the role of MT during the experimental development of arterial hypertension. Control and transgenic MT -/- mice were submitted to an 8-week mineralocorticoid-salt treatment. Hepatic glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase activities and cardiac MT and mineral levels were measured. Mineralocorticoid-salt treatment induced an increase in blood pressure in both transgenic MT -/- and control mice that was associated with an impairment of liver antioxidant status. MT deficiency was associated with modifications of hepatic antioxidant enzyme activities and with a decrease in cardiac iron levels. Adaptive processes of antioxidant systems may explain the absence of an effect of metallothionein deficiency on the development of mineralocorticoid-salt hypertension. The interactions that occur between the in vivo antioxidant systems probably produce a complex regulation of the oxidative balance and consequently prevent antioxidant deficiency.

Topics: Animals; Antioxidants; Blood Pressure; Body Weight; Catalase; Desoxycorticosterone; Drug Administration Schedule; Female; Glutathione Peroxidase; Glutathione Reductase; Heart Rate; Hypertension; Liver; Male; Metallothionein; Mice; Mice, Transgenic; Myocardium; Superoxide Dismutase

Because oxidative stress may be involved in arterial hypertension by affecting the balance between relaxing and contracting factors of vascular smooth muscle, the training-induced adaptation of antioxidant defenses could be implicated in the antihypertensive effect of chronic exercise. It has been suggested that metallothionein (MT), a metal-binding protein, plays an antioxidant role in mammals. The aim of this experiment was to study whether chronic exercise (swimming) influences both the development of arterial hypertension in spontaneously hypertensive rats (SHR) and the modification of MT levels.. Male SHR and Wistar Kyoto (WKY) rats as control were trained to swim 1 h.d-1 5 d.wk-1 for 8 wk and sacrificed 72 h after the last exercise period. MT and total thiol levels were then measured.. Exercise training 1) reduced systolic blood pressure and heart rate in both SHR WKY rats, and 2) was associated with a decrease in hepatic and cardiac MT levels; there was an increase in the aortic MT amounts in exercised SHR only. No modifications were noted in the gastrocnemius muscle or kidneys. In exercised animals, total thiols were lower in the liver but not in kidneys.. Chronic exercise induced a reduction in arterial hypertension development in SHR rats and an adaptation of the MT levels in cardiac, hepatic, and aortic tissues. Further experiments are needed to pinpoint the role of the MT in these two cases in which oxidative stress occurs.

Topics: Animals; Aorta; Disease Models, Animal; Heart Rate; Hypertension; Liver; Male; Metallothionein; Myocardium; Physical Conditioning, Animal; Rats; Rats, Inbred SHR; Rats, Wistar

The tissue kallikrein-kinin system has been postulated to play a role in blood pressure homeostasis and the pathogenesis of clinical hypertension. To demonstrate the potential therapeutic effects of somatic gene delivery in treating hypertension, we used spontaneously hypertensive rats (SHR) as a model. The gene encoding the human tissue kallikrein was used because of its powerful hypotensive action. The human kallikrein DNA constructs were placed under the control of the metallothionein metal response element, the cytomegalovirus promoter/enhancer or the Rous sarcoma virus 3'-LTR. The human tissue kallikrein DNA constructs were incorporated into adenoviral vectors via homologous recombination. The naked plasmid DNA constructs or adenovirus containing the kallikrein gene were first introduced into kidney 293 cells and the expression of human tissue kallikrein was identified by ELISA. The kallikrein gene was delivered into SHR via intramuscular, intravenous, portal vein, intraperitoneal, and intracerebroventricular routes. A single injection of naked human kallikrein DNA constructs caused a prolonged reduction of high blood pressure for up to 8 weeks. Adenoviral-mediated gene delivery results in high efficiency of human tissue kallikrein expression. Immunoreactive human kallikrein was detected in rat serum at the highest level at 1 day post gene delivery. Portal vein delivery of a reporter gene, AdCMV-LacZ, results in intense staining of beta-galactosidase in rat liver, suggesting that recombinant kallikrein is mainly produced in liver and secreted into the circulation. These results show that kallikrein gene delivery causes a sustained reduction of blood pressure in genetically hypertensive rats and provide important information for a potential gene therapy approach to human hypertension and related diseases.

Topics: Animals; Avian Sarcoma Viruses; beta-Galactosidase; Blood Pressure; Cytomegalovirus; DNA, Viral; Gene Expression Regulation, Viral; Genes, Reporter; Genetic Therapy; Genetic Vectors; Humans; Hypertension; Injections, Intramuscular; Injections, Intraperitoneal; Injections, Intravenous; Injections, Intraventricular; Kallikrein-Kinin System; Kallikreins; Lac Operon; Metallothionein; Plasmids; Promoter Regions, Genetic; Rats; Rats, Inbred SHR; Time Factors; Tissue Kallikreins

The metallothionein (MT) synthesis was induced in the liver of spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats through sc injections of CdCl2 for 3 and 6 days. The MT contents of the liver of these animals and of untreated rats from both groups were determined by gel filtration, HPLC, SDS/PAGE and amino acid analysis. The isoforms MT1 and MT2 were identified and their Cd, Zn and SH-group contents were determined. The SHR showed significantly higher values of MT than WKY rats in the untreated animals and on the 3rd day of the induction. On the 6th day, the MT levels in both groups were equal. The Cd and Zn contents followed the MT concentration in the homogenates. The possible relation between the arterial hypertension and the zinc and copper homeostasis is discussed.

Topics: Amino Acids; Animals; Cadmium; Cadmium Chloride; Chlorides; Hypertension; Liver; Metallothionein; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Laboratory animals have a unique sensitivity to cadmium toxicity in late pregnancy. This acute toxicity is not seen in non-pregnant, early pregnant, or lactating animals. Furthermore, during late pregnancy, laboratory animals absorb and retain substantially more cadmium from their diets than they do in the non-pregnant state. Both of these observations parallel the fact that a fivefold late gestational drop of maternal metallothionein (a metal-binding protein believed to detoxify cadmium) has been demonstrated in pregnant animals. Additional factors such as nutritional status and age affect cadmium absorption. As we have discussed previously, cadmium toxicity and toxemia of pregnancy have many common features including hypertension, proteinuria, edema, vasospasm and endovasculitis. Because of the above, we propose that cadmium plays a role in the etiology of toxemia.

Topics: Animals; Cadmium; Female; Humans; Hypertension; Maternal-Fetal Exchange; Metallothionein; Pre-Eclampsia; Pregnancy; Rats

Cadmium, a toxic heavy metal, has been incriminated in the etiology of essential hypertension. Zinc, an essential micronutrient necessary for growth, competes with cadmium for binding sites in biochemical processes; zinc deficiency states (i.e. pregnancy and low protein diet) might expose an individual to increased risk of cadmium toxicity. The increased sensitivity to cadmium during pregnancy could also be related to the effect of progesterone on zinc and cadmium metabolism through the actions of metallothionein (MT). MT is a low molecular weight protein believed to function in cadmium detoxification. Several studies in lab animals have documented a late gestation drop of maternal MT levels. This was thought to be due to rising progesterone levels. If there is also a late gestation drop in human maternal MT, then the propensity toward maternal cadmium toxicity would be enhanced. Therefore, we propose that when a zinc deficient woman becomes pregnant and is exposed to both the nutritional demands of the fetus and to the influence of progesterone, she will be likely to develop the manifestations of cadmium toxicity (i.e. hypertension, proteinuria, edema, etc.).

Topics: Animals; Cadmium; Female; Humans; Hypertension; Metallothionein; Models, Biological; Pre-Eclampsia; Pregnancy; Pregnancy Complications, Cardiovascular; Progesterone; Zinc