General measures of cardiac performance were done by in situ left ventricle (LV) hemodynamic analysis, as described previously ( 31). Histopathological and immunohistochemical examination by light microscopy. mouse −1 to maintain the blood glucose levels between 5.6 and 11.2 mmol/l with an average of 7.6 ± 1.1 mmol/l, until they were killed.For these mice, when hyperglycemia was diagnosed 2 or 3 days after STZ treatment, insulin was immediately given three times (8-h interval) using Humulin U (Eli Lilly, Indianapolis, IN) at a concentration of 10 units To eliminate the effects of STZ on cardiotoxicity, insulin-treated diabetic mice were used. STZ-treated mice with glucose levels higher than 12 mmol/l were considered diabetic, and mice serving as controls were given the same volume of sodium citrate ( 5). Whole-blood glucose obtained from the mouse tail vein was detected using a SureStep complete blood glucose monitor (LifeScan, Milpitas, CA) 2 and 3 days after STZ treatment. Louis, MO) dissolved in sodium citrate buffer (pH 4.5). These results thus suggest that metallothionein prevention of diabetic cardiomyopathy is mediated, at least in part, by suppression of superoxide generation and associated nitrosative damage.Įight-week-old male mice were given a single dose of STZ (150 mg/kg body wt i.p. Either urate, a peroxynitrite-specific scavenger, or Mn(111) tetrakis 1-methyl 4-pyridyl porphyrin pentachloride (MnTMPyP), a superoxide dismutase mimic, significantly inhibited the formation of 3-NT along with a significant prevention of cytotoxicity. Increases in 3-NT formation and cytotoxicity were observed in wild-type, but not in MT-TG, cardiomyocytes. Furthermore, primary cultures of cardiomyocytes from wild-type and MT-TG mice were exposed to lipopolysaccharide/tumor necrosis factor-α for generating intracellular peroxynitrite. Formations of superoxide and 3-nitrotyrosine (3-NT), a marker for peroxynitrite-induced protein damage, were detected only in the heart of wild-type diabetic mice. However, the development of diabetic cardiomyopathy, revealed by histopathological and ultrastructural examination, serum creatine phosphokinase, and cardiac hemodynamic analysis, was significantly observed only in the wild-type, but not in MT-TG, diabetic mice 2 weeks and 6 months after STZ treatment. Cardiac-specific metallothionein-overexpressing transgenic (MT-TG) mice and wild-type littermate controls were treated with streptozotocin (STZ) by a single intraperitoneal injection, and both developed diabetes. The present study was performed to test whether inhibition of nitrosative damage is involved in metallothionein prevention of diabetic cardiomyopathy. The energy splitting is estimated from the diagonal elements of the g tensor of 1.The mechanisms of metallothionein prevention of diabetic cardiomyopathy are largely unknown. #Superoxide d splitt freeThe Pi(g) energy levels which are degenerate in the free superoxide ion split up in crystal fields of lower than tetragonal symmetry. The g tensors themselves reflect the anisotropic environment of the superoxide ions. The values of the magnetic moment comply well with the g factors obtained from electron paramagnetic resonance spectra. The effective magnetic moments of both compounds are larger than the spin-only value due to contributions of the orbital momentum in the superoxide ion. Magnetization measurements show that the susceptibilities of both compounds follow an ideal Curie law down to 2 K reflecting an absence of intermolecular exchange effects between the superoxide ions. Therefore, it represents the best known approximation to the virtually isolated superoxide ion in the solid state to date. The crystal structure of 1 does not contain any solvent molecules. The crystal structure of 2 contains solvent ammonia molecules that are hydrogen bonded to the superoxide ion and therefore may influence the bonding properties of the superoxide ion. Both compounds were structurally characterized by single-crystal X-ray diffraction. Trimethylphenylammonium superoxide (1) and tetrabutylammonium superoxide (2) were prepared by ion-exchange reaction in liquid ammonia.
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