1-3-dimethylthiourea and Myocardial-Infarction

Fox nut or gorgon nut (Euryale ferox--Family Nymphaeaceae), popularly known as Makhana, has been widely used in traditional oriental medicine to cure a variety of diseases including kidney problems, chronic diarrhea, excessive leucorrhea and hypofunction of the spleen. Based on the recent studies revealing antioxidant activities of Euryale ferox and its glucosides composition, we sought to determine if Euryale ferox seeds (Makhana) could reduce myocardial ischemic reperfusion injury. Two different models were used: acute model, where isolated rat hearts were preperfused for 15 min with Krebs Henseleit bicarbonate (KHB) buffer containing three different doses of makhana (25, 125 or 250 microg/ml) followed by 30 min of ischemia and 2 h of reperfusion; and chronic model, where rats were given two different doses of makhana (250 and 500 mg/kg/day) for 21 days, after which isolated hearts were subjected to 30 min of ischemia followed by 2 h of reperfusion. In both cases, the hearts of the Makhana treated rats were resistant to ischemic reperfusion injury as evidenced by their improved post-ischemic ventricular function and reduced myocardial infarct size. Antibody array technique was used to identify the cardioprotective proteins. The Makhana-treated hearts had increased amounts of thioredoxin-1 (Trx-1) and thioredoxin-related protein-32 (TRP32) compared to the control hearts. Western blot analysis confirmed increased expression of TRP32 and thioredoxin proteins. In vitro studies revealed that Makhana extracts had potent reactive oxygen species scavenging activities. Taken together, the results of this study demonstrate cardioprotective properties of Makhana and suggest that such cardioprotective properties may be linked with the ability of makhana to induce TRP32 and Trx-1 proteins and to scavenge ROS.

Topics: Animals; Blotting, Western; Free Radical Scavengers; Heart Ventricles; In Vitro Techniques; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Nymphaeaceae; Phytotherapy; Plant Extracts; Plant Leaves; Protein Array Analysis; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Seeds; Superoxide Dismutase; Thiourea

Heme oxygenase-1 (H(mox-1)) has been implicated in protection of cells against ischemia/reperfusion injury.. To examine the physiological role of H(mox-1), a line of heterozygous H(mox-1)-knockout mice was developed by targeted disruption of the mouse H(mox-1) gene. Transgene integration was confirmed and characterized at the protein level. A 40% reduction of H(mox-1) protein occurred in the hearts of H(mox-1)(+/)(-) mice compared with those of wild-type mice. Isolated mouse hearts from H(mox-1)(+/)(-) mice and wild-type controls perfused via the Langendorff mode were subjected to 30 minutes of ischemia followed by 120 minutes of reperfusion. The H(mox-1)(+/)(-) hearts displayed reduced ventricular recovery, increased creatine kinase release, and increased infarct size compared with those of wild-type controls, indicating that these H(mox-1)(+/)(-) hearts were more susceptible to ischemia/reperfusion injury than wild-type controls. These results also suggest that H(mox-1)(+/)(-) hearts are subjected to increased amounts of oxidative stress. Treatment with 2 different antioxidants, Trolox or N:-acetylcysteine, only partially rescued the H(mox-1)(+/)(-) hearts from ischemia/reperfusion injury. Preconditioning, which renders the heart tolerant to subsequent lethal ischemia/reperfusion, failed to adapt the hearts of the H(mox-1)(+/)(-) mice compared with wild-type hearts.. These results demonstrate that H(mox-1) plays a crucial role in ischemia/reperfusion injury not only by functioning as an intracellular antioxidant but also by inducing its own expression under stressful conditions such as preconditioning.

Topics: Acetylcysteine; Animals; Antioxidants; Chromans; Creatine Kinase; Disease Models, Animal; Gene Targeting; Heart; Heart Rate; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Heterozygote; In Vitro Techniques; Ischemic Preconditioning, Myocardial; Malondialdehyde; Membrane Proteins; Mice; Mice, Transgenic; Myocardial Contraction; Myocardial Infarction; Myocardial Ischemia; Myocardium; Reperfusion Injury; Thiourea

Oxidative stress might play an important role in the progression of left ventricular (LV) remodeling and failure that occur after myocardial infarction (MI). We determined whether reactive oxygen species (ROS) are increased in the LV remodeling and failure in experimental MI with the use of electron spin resonance spectroscopy and whether the long-term administration of dimethylthiourea (DMTU), hydroxyl radical (.OH) scavenger, could attenuate these changes. We studied 3 groups of mice: sham-operated (sham), MI, and MI animals that received DMTU (MI+DMTU). Drugs were administered to the animals daily via intraperitoneal injection for 4 weeks.OH was increased in the noninfarcted myocardium from MI animals, which was abolished in MI+DMTU. Fractional shortening was depressed by 65%, LV chamber diameter was increased by 53%, and the thickness of noninfarcted myocardium was increased by 37% in MI. MI+DMTU animals had significantly better LV contractile function and smaller increases in LV chamber size and hypertrophy than MI animals. Changes in myocyte cross-sectional area determined with LV mid-free wall specimens were concordant with the wall thickness data. Collagen volume fraction of the noninfarcted myocardium showed significant increases in the MI, which were also attenuated with DMTU. Myocardial matrix metalloproteinase-2 activity, measured with gelatin zymography, was increased with MI after 7 and 28 days, which was attenuated in MI+DMTU. Thus, the attenuation of increased myocardial ROS and metalloproteinase activity with DMTU may contribute, at least in part, to its beneficial effects on LV remodeling and failure. Therapies designed to interfere with oxidative stress might be beneficial to prevent myocardial failure.

Topics: Animals; Body Weight; Cyclic N-Oxides; Echocardiography; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Hemodynamics; Male; Matrix Metalloproteinases; Mice; Myocardial Infarction; Myocardium; Organ Size; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species; Spin Labels; Thiourea; Ventricular Dysfunction, Left; Ventricular Remodeling

The effects of EUK-8, a synthetic, catalytic scavenger of reactive oxygen species, on isolated iron-overloaded rat hearts submitted to ischemia-reperfusion were studied. In the absence of EUK-8, functional parameters (systolic and diastolic pressures, oxygen consumption as estimated by the product heart rate times left ventricular diastolic pressure) were severely impaired 1 minute and 15 minutes after reperfusion following a 15 minute ischemic episode. Dimethylthiourea (10 mM), a hydroxyl radical scavenger, had a minimally protective effect. In contrast, EUK-8 at a concentration of 50 microM in the perfusion medium maintained these parameters at close to their preischemia values. Electron microscopic analysis of heart tissues after 15 minutes ischemia followed by 15 minutes reperfusion showed extensive damage to mitochondria and sarcomeres in untreated hearts, while the extent of damage was significantly lower in EUK-8-treated hearts. The functional and structural protection afforded by EUK-8 were significantly better than those induced by dimethylthiourea. These data suggest that EUK-8 may be therapeutically useful in preventing heart damage induced by ischemia-reperfusion, for example, during thrombolytic treatment of myocardial infarction.

Topics: Animals; Blood Pressure; Dextrans; Disease Models, Animal; Electron Spin Resonance Spectroscopy; Ethylenediamines; Female; Free Radical Scavengers; Heart Rate; Heart Ventricles; Iron; Manganese; Microscopy, Electron; Mitochondria, Heart; Myocardial Infarction; Myocardial Reperfusion Injury; Organometallic Compounds; Oxygen Consumption; Rats; Rats, Wistar; Reactive Oxygen Species; Thiourea

Ischaemic preconditioning may be mediated by oxygen free radicals generated during preconditioning. Conflicting results have been reported regarding the effect of superoxide dismutase (SOD) in attenuating the cardioprotective effect of preconditioning. The aim of the study was to reconcile this conflict by examining the effect of three different oxyradical scavengers on the infarct size limiting effect of preconditioning.. Anaesthetised open chest rabbits were subjected to 30 min coronary occlusion and 48 h reperfusion. In the preconditioning groups, rabbits were subjected to a single 5 min occlusion and 5 min reperfusion before 30 min sustained ischaemia. In these groups, the oxyradical scavengers SOD (15,000 U.kg-1), N-2-mercaptopropionyl glycine (MPG, 20 mg.kg-1), and dimethylthiourea (DMTU, 500 mg.kg-1), or placebo saline, were infused before and during preconditioning. In the non-preconditioning groups, these agents were given in the same time frame before 30 min of ischaemia. After 2 d reperfusion, infarct size was measured microscopically.. In the saline treated controls, preconditioning markedly limited microscopical infarct size (percent of area at risk): 13(SEM 3)% (n = 9) v 49(9)% (n = 8), p < 0.05. Treatment of the preconditioning groups with SOD or MPG attenuated this cardioprotection [infarct size 31(5)% (n = 11) and 42(8)% (n = 11), respectively, p < 0.05 v the saline treated preconditioning group], but treatment with DMTU did not [infarct size 23(6)% (n = 11), p = NS v the saline treated preconditioning group]. In the non-preconditioning groups, none of the treatments modified infarct size: 50(9)% (n = 7), 56(5)% (n = 8), and 61(6)%, (n = 8), respectively, p = NS v saline treated control.. Cardioprotection by preconditioning is mediated, at least in part, by oxyradicals which are scavenged by SOD or MPG in rabbits.

Topics: Animals; Free Radicals; Male; Myocardial Infarction; Myocardial Ischemia; Myocardium; Rabbits; Superoxide Dismutase; Thiourea; Tiopronin

Topics: Animals; Cardiac Output; Creatine Kinase; Dogs; Hemodynamics; Malondialdehyde; Myocardial Infarction; Myocardial Reperfusion Injury; Reactive Oxygen Species; Thiourea; Time Factors

Topics: Animals; Dogs; Free Radical Scavengers; Myocardial Infarction; Myocardial Reperfusion Injury; Necrosis; Rabbits; Thiourea

This study examined the effect of treatment with dimethylthiourea (DMTU), a highly cell-permeable scavenger of hydroxyl radicals, on tissue necrosis in rabbit hearts during myocardial ischemia and reperfusion. Sixty-two rabbits underwent 45 minutes of coronary occlusion with, or without, coronary reperfusion for 3 hours. A saline vehicle, or DMTU (500 mg/kg intravenously [iv]) was administered over 45 minutes starting either 10 minutes before or 10 minutes after coronary occlusion, or 10 minutes before coronary reperfusion. Anatomic risk zone size was assessed using microsphere autoradiography, and the area of necrosis was determined using tetrazolium staining. Cardiac hemodynamics and risk zone size were similar for all treatment groups. No differences were observed in the extent of tissue necrosis (normalized to risk zone size) for saline- and DMTU-treated rabbits subjected to 45 minutes (61.2 +/- 23.1% vs. 70.6 +/- 16.5%) or 225 minutes (82.8 +/- 5.4% vs. 78.3 +/- 5.9%) of permanent coronary occlusion without reperfusion. Similarly, tissue necrosis in rabbits with 45 minutes coronary occlusion followed by 3 hours reperfusion was not significantly reduced when DMTU was administered either 10 minutes before coronary occlusion, 10 minutes after coronary occlusion, or 10 minutes before coronary reperfusion (67.0 +/- 9.9%; 57.6 +/- 10.6%; 68.3 +/- 13.3%) compared to saline-treated controls (76.6 +/- 10.5%). These results demonstrate that the hydroxyl radical scavenger DMTU does not appear to influence the progression of myocyte injury in this experimental model of acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Coronary Disease; Hemodynamics; Male; Myocardial Infarction; Myocardial Reperfusion; Myocardium; Necrosis; Rabbits; Thiourea

A number of scavengers of reactive oxygen metabolites reduce myocardial injury when given before ischemia and reperfusion, but few, if any, have proven to be effective when given near the onset of reperfusion. This is particularly true when infarct size is measured after at least 48 hours of reperfusion, when the full extent of myocardial damage has become apparent. Dimethylthiourea (DMTU) is an extremely diffusible, potent scavenger of hydroxyl radical, hydrogen peroxide, and hypochlorous acid, with a long half-life of 43 hours. Sixteen chloralose-anesthetized dogs underwent 90 minutes of left anterior descending coronary artery (LAD) occlusion followed by 48 hours of reperfusion. Collateral flow was measured by radioactive microspheres. Infarct size and risk area were measured by a postmortem dual-perfusion technique using triphenyl tetrazolium chloride and Evan's blue dye. In eight dogs, therapy with DMTU (500 mg/kg i.v.) was given during the last 15 minutes of ischemia and the first 15 minutes of reperfusion. In eight control dogs, the same volume of 0.9% saline was given during the last 15 minutes of ischemia through the first 15 minutes of reperfusion. Infarct size as a percent of risk area was reduced in the DMTU-treated group compared with the saline-treated controls (DMTU = 42 +/- 4% versus saline = 59 +/- 4%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Coronary Circulation; Dogs; Free Radical Scavengers; Hemodynamics; Male; Myocardial Infarction; Myocardial Reperfusion; Myocardial Reperfusion Injury; Myocardium; Oxygen; Staining and Labeling; Tetrazolium Salts; Thiourea

We studied the effect of treatment with two diffusible, low molecular weight scavengers of toxic oxygen metabolites, dimethylthiourea (DMTU) and dimethylsulfoxide (DMSO), on canine infarcts caused by 90 min of ischemia and 3 h of reperfusion. Infarct size was determined by incubating ventricular slices with triphenyl tetrazolium chloride. Areas at risk were determined by autoradiography of 99Tc microspheres injected in vivo during ischemia and were similar (p greater than 0.05) in DMTU, DMSO, and saline treated dogs. However, the ratio of infarct size to area at risk was reduced (p less than 0.05) in dogs treated 30 min before reperfusion with 500 mg/kg DMTU (31.1 +/- 4.6%, n = 9) compared with saline treated dogs (53.4 +/- 4.6% n = 9). In contrast, the ratio of infarct size to area at risk was not significantly different (p greater than 0.05) in dogs treated with 2000 mg/kg DMSO 30 min before reperfusion (43.7 +/- 4.3%) compared to saline treated dogs. The serum concentration of DMTU (4.5 mM) was one-tenth that of DMSO (48 mM) in early reperfusion. Therefore, DMTU but not DMSO protected against post-ischemic cardiac reperfusion injury.

Topics: Animals; Blood Gas Analysis; Dimethyl Sulfoxide; Dogs; Hematocrit; Hemodynamics; Microspheres; Myocardial Infarction; Osmolar Concentration; Reperfusion Injury; Thiourea