Erythropoietin, but not asialoerythropoietin or carbamyl-erythropoietin, attenuates monocrotaline-induced pulmonary hypertension in rats.

Erythropoietin (EPO) has long been utilized for the treatment of renal anemia. The erythropoietin receptor (EPOR) is also expressed in the cardiovascular and central nervous systems in addition to an erythroid lineage, to provide an organoprotective role against several types of cellular stress. Pulmonary hypertension (PH) is a poor prognostic disease caused by primary and secondary pulmonary vascular injury. We observed the effects of EPO derivatives on monocrotaline-induced PH in rats on the supposition that EPO may protect small arteries from injury. Asialoerythropoietin (AEPO) lacks sialic acids in the termini of carbohydrate chains that results in rapid clearance from blood. Carbamyl-erythropoietin (CEPO) interacts with EPOR/ßc heterodimers, but not with EPOR homodimers expressed in erythroid cells. Monocrotaline-injected rats were treated with continuous intravenous injection of 2500 ng/kg/day of EPO, AEPO, or CEPO for 21 days, and lung histology, cardiac function, and mRNA expression in the lungs were examined. Wall thickening of small arteries in the lungs and PH were improved by administration of EPO, but not by its non-hematopoietic derivatives, AEPO, or CEPO. Erythropoietin administration increased mRNA expression of the anti-apoptotic molecule, Bcl-xL, and maintained expression of the CD31 antigen. We conclude that lungs may express EPOR homoreceptors, but not heteroreceptors. Adequate serum erythropoietin levels may be essential for pulmonary protective effects.

IL-1 receptor accessory protein-Ig/IL-1 receptor type II-Ig heterodimer inhibits IL-1 response more strongly than other IL-1 blocking biopharmaceutical agents.

INTRODUCTION: Interleukin (IL)-1 is a key orchestrator of inflammation and IL-1 inhibitors are expected to be promising pharmaceutical agents for such pathologies. IL-1 is bound to the complex of two receptor components with much higher affinity than with either receptor component alone. MATERIALS AND METHODS: We examined the effect of a heterodimer of IL-1 receptor accessory protein (Acp)-immunoglobulin (Ig) and IL-1R type II (IL1R2)-Ig named AcP-Ig/IL1R2-Ig heterodimer, and compared its effects with other IL-1 inhibitors reported previously. RESULTS AND DISCUSSION: Our results demonstrated that the rat AcP-Ig/IL1R2-Ig heterodimer (IC50=1.95 pM) inhibited IL-1 response to a greater extent than IL1RA (IC50=1,935 pM), Acp-IL1R type I (IL1R1)-Ig homodimer (IC50=73.7 pM) and Acp-IL1R2-Ig homodimer (IC50=72.8 pM). Moreover, human AcP-Ig/IL1R2-Ig heterodimer (IC50=0.14 pM) inhibited it to a greater extent than Acp-IL1R1-Ig homodimer (IC50=4.48 pM) and strongly inhibited responses of both IL-1α and IL-1ß. CONCLUSIONS: The AcP-Ig/IL1R2-Ig heterodimer, which is similar to the original extracellular structure of the Acp/IL1R1 complex, may inhibit the IL-1 response more vigorously than other IL-1 blocking biopharmaceutical agents.

Effects of sulfaphenazole derivatives on cardiac ischemia-reperfusion injury: association of cytochrome P450 activity and infarct size.

Cardiac ischemia-reperfusion injury is evoked by reactive oxygen species (ROS). We previously reported that sulfaphenazole (SPZ) attenuated cardiac ROS levels and ischemia-reperfusion injury in rats. SPZ has distinct two actions: a) elimination of ROS and b) inhibition of cytochrome P450 (CYP) that is responsible for ROS production. The aim of this study is to determine which action contributes to the attenuation of cardiac ischemia-reperfusion injury using SPZ and its derivatives [acetyl-SPZ (Ac-SPZ) and dichloro-SPZ (2Cl-SPZ)]. Administration of 2Cl-SPZ or SPZ prior to ischemia significantly reduced myocardial infarct size, myocardial lipid peroxides, and ROS levels. In addition, they inhibited rat cardiac CYP activity. However, Ac-SPZ neither reduced infarct size nor inhibited cardiac CYP activity. The three compounds had similar effects on ROS scavenging activity in that they scarcely scavenged hydrogen peroxide and superoxide anions but reduced hydroxyl radicals with the same efficacy. The serum concentration of each compound was almost the same until 24 h after reperfusion. Collectively, our findings indicate that the suppressive effects of SPZ and 2Cl-SPZ on ischemia-reperfusion injury are associated with the reduction of ROS levels, which is primarily due to a decrease in ROS production via inhibition of cardiac CYP, not via ROS scavenging activity.

Functional proteomic analysis of experimental autoimmune myocarditis-induced chronic heart failure in the rat.

Experimental autoimmune myocarditis (EAM)-induced heart failure in rats is used to study the pathogenesis of heart failure. Based on a proteomic analysis of soluble (S) and membranous (M) fractions extracted from ventricles of rats with a stable chronic form of EAM-induced heart failure, we assessed changes in protein levels and their correlation to heart functions to gain insights into the pathogenesis and to explore new targets for the treatment of heart failure. Proteins were separated by two-dimensional gel electrophoresis and silver stained spots were analyzed. In the S-fraction, 274+/-3 spots were detected in the normal (N)-group and 273+/-6 in the heart failure (HF)-group. In the HF-group, 26 of the spots were increased and 15 were decreased in intensity. In the M-fraction, 277+/-3 spots were detected in the N-group and 277+/-2 in the HF-group, with 20 spots increased and 10 decreased in intensity. We analyzed relationships between the expression of these proteins and 11 parameters of heart function, and found all the significantly changed spots to correlate with at least one of the parameters. We analyzed 49 spots that correlated with over 9 parameters of heart function using mass spectrometry, and identified 15 as proteins with increased expression including glucose regulated protein (GRP)78, an endoplasmic-stress related protein, and heat shock protein (HSP)90beta, a molecular chaperone, and 4 spots as proteins with decreased expression. It is suggested that in the heart failure model, GRP78 and HSP90beta play a role in the protection or deterioration of the heart and may be new targets for treatment.

A study of cardiovascular function in Tsumura Suzuki obese diabetes, a new model mouse of type 2 diabetes.

Diabetes mellitus is a well known and important risk factor for cardiovascular diseases, including heart failure. A new model of Type 2 diabetes, Tsumura Suzuki Obese Diabetes (TSOD) mice, was introduced recently into the research field of diabetes. The cardiac functions of TSOD mice were studied in comparison with Tsumura Suzuki Non Obesity (TSNO, non-diabetic control) mice, for the first time. In vivo cardiovascular functions were measured by echocardiography and cardiac catheterization at 7, 12 and 18 months old. TSOD mice had no deterioration of cardiac function despite the long-term persistence of severe obesity, hyperglycemia, hyperinsulinemia and hyperlipidemia, including high density lipoprotein (HDL)-cholesterol. No histopathological abnormalities were observed in the heart of TSOD mice, while several histological abnormalities were observed in the pancreas and kidney of TSOD mice. To investigate vascular endothelium function at 7 months old, intravenous injection of acetylcholine (ACh; 1, 3, 10 microg/kg)- and N(G)-nitro-L-arginine methyl ester (L-NAME; 50 mg/kg)-induced mean blood pressure (BP) changes were used. ACh decreased whereas L-NAME increased BP, and no significant differences in BP changes were observed between TSOD and TSNO mice. Moreover, ACh-induced relaxation of the thoracic aortae isolated from TSOD and TSNO mice with intact endothelium were not significantly different. These findings suggest that vascular endothelial cells in TSOD mice are not impaired. It was clearly demonstrated that despite obvious diabetes, cardiac functions of TSOD mice were not impaired even at 18 months old.

Long-term carperitide treatment attenuates left ventricular remodeling in rats with heart failure after autoimmune myocarditis.

The effect of carperitide, recombinant human atrial natriuretic peptide, on chronic heart failure (HF) has not been clarified. We investigated the beneficial effects of chronic carperitide treatment in rats with HF after experimental autoimmune myocarditis. A 28-day infusion of carperitide (n = 14) or vehicle (n = 14) was administrated to the rats 4 weeks after experimental autoimmune myocarditis induction. After 4 weeks, the myocardial levels of cyclic guanosine monophosphate (cGMP), left ventricular function, myocyte hypertrophy, interstitial fibrosis, myocardial capillary vessel density, and activity of one prominent substrate of cGMP, vasodilator-stimulated phosphoprotein (VASP) that may enhance angiogenesis, were measured. Carperitide treatment increased the myocardial levels of cGMP and attenuated the functional severity along with a decreased myocyte cross-sectional area, interstitial fibrosis, and an increased capillary to myocyte ratio. Furthermore, carperitide treatment enhanced the phosphorylation of VASP at Ser239, which was preferentially phosphorylated by cGMP-dependent protein kinase but not Ser157, which was preferentially phosphorylated by cyclic adenosine monophosphate-dependent protein kinase. Long-term carperitide treatment attenuates ventricular remodeling and ameliorates the progression of chronic HF. The effects of carperitide treatment are associated with increased neovascularization among the residual myocytes and an increase of VASP activation.

Comparative effects of olmesartan and azelnidipine on atrial structural remodeling in spontaneously hypertensive rats.

The differential effects between olmesartan (OM), an angiotensin 2 type 1 receptor blocker (ARB), and azelnidipine (AZ), a calcium channel blocker (CCB), on atrial structural remodeling were studied in spontaneously hypertensive rats (SHR). Eight weeks after treatment, both OM and AZ decreased systolic blood pressure to similar levels. Histological analysis revealed that both OM and AZ had decreased the size of the atrial myocytes and interstitial fibrosis in the atrium, and that the effects of OM were greater than those of AZ. These beneficial effects of OM were associated with less atrial oxidative stress, as assessed by 3-nitrotyrosine staining, and less activation of Rac1, a regulatory component in NADPH oxidase. These results suggest that the ARB was more effective than the CCB in ameliorating atrial structural remodeling due to the suppression of oxidative stress.

Which skeletal myoblasts and how to be transplanted for cardiac repair?

Clinical efficacy of skeletal myoblast (skMb) transplantation is controversial whether this treatment produces beneficial outcome in patients with dilated cardiomyopathy (DCM). Based on immunological tolerance between wild-type and DCM hamsters with the deletion of delta-sarcoglycan (SG) gene, skMb engraftment in TO-2 myocardium (3x10(5) cells in approximately 100mg heart) was verified by the donor-specific expression of delta-SG transgene constitutively produced throughout myogenesis. At 5 weeks after the transplantation, the cell rates expressing fast-myosin heavy chain (MHC) exceeded slow-MHC in delta-SG(+) cells. Fifteen weeks after (corresponding to approximately 12 years in humans), fast MHC(+) cells nullified, but the delta-SG(+) and slow MHC(+) cell number remained unaltered. These skMbs fused with host cardiomyocytes via connexin-43 and intercalated disc, modestly improving the hemodynamics without arrhythmia, when engrafted skMbs were sparsely disseminated in autopsied myocardium. These results provide us evidence that disseminating delivery of slow-MHC(+) myoblasts is promising for repairing DCM heart using histocompatible skeletal myoblasts in future.

A novel scheme of dystrophin disruption for the progression of advanced heart failure.

The precise mechanism of the progression of advanced heart failure is unknown. We assessed a new scheme in two heart failure models: (I) congenital dilated cardiomyopathy (DCM) in TO-2 strain hamsters lacking delta-sarcoglycan (SG) gene and (II) administration of a high-dose of isoproterenol, as an acute heart failure in normal rats. In TO-2 hamsters, we followed the time course of the histological, physiological and metabolic the progressions of heart failure to the end stage. Dystrophin localization detected by immunostaining age-dependently to the myoplasm and the in situ sarcolemma fragility evaluated by Evans blue entry was increased in the same cardiomyocytes. Western blotting revealed a limited cleavage of the dystrophin protein at the rod domain, strongly suggesting a contribution of endogenous protease(s). We found a remarkable up-regulation of the amount of calpain-1 and -2, and no change of their counterpart, calpastatin. After supplementing TO-2 hearts with the normal delta-SG gene in vivo, these pathological alterations and the animals' survival improved. Furthermore, dystrophin but not delta-SG was disrupted by a high dose of isoproterenol, translocated from the sarcolemma to the myoplasm and fragmented. These results of heart failure, irrespective of the hereditary or acquired origin, indicate a vicious cycle formed by the increased sarcolemma permeability, preferential activation of calpain over calpastatin, and translocation and cleavage of dystrophin would commonly lead to advanced heart failure.

Effect of hydrodynamics-based gene delivery of plasmid DNA encoding interleukin-1 receptor antagonist-Ig for treatment of rat autoimmune myocarditis: possible mechanism for lymphocytes and noncardiac cells.

BACKGROUND: Interleukin-1 (IL-1) is a powerful and important cytokine in myocarditis. The purpose of this study was to evaluate the effect and possible mechanism of hydrodynamics-based delivery of the IL-1 receptor antagonist (IL-1RA)-immunoglobulin (Ig) gene for treatment of rat experimental autoimmune myocarditis (EAM). METHODS AND RESULTS: On the day after immunization, rats were transfected with either pCAGGS encoding IL-1RA-Ig or pCAGGS encoding Ig alone. On day 17, IL-1RA-Ig gene therapy was effective in controlling EAM, as monitored by a decreased ratio of heart weight to body weight, reduced myocarditis areas, reduced gene expression of atrial natriuretic peptide in hearts, and improved cardiac function in echocardiographic and hemodynamic parameters. Examination of the expression of IL-1-related genes in purified cells from EAM hearts suggested that ectopic IL-1RA-Ig-acting target cells were alphabetaT cells and noncardiomyocytic noninflammatory cells such as fibroblasts, smooth muscle cells, and endothelial cells. Therefore, we examined the effect of serum containing IL-1RA-Ig on the expression of immune-relevant genes within noncardiomyocytic cells cultured from EAM hearts or concanavalin A-stimulated lymphocytes derived from lymph nodes in EAM-affected rats. The expression of immunologic molecules (prostaglandin E synthase, cyclooxygenase-2, and IL-1beta) in cultivated noncardiomyocytic cells and Th1 cytokines (IL-2 and IFN-gamma) in lymphocytes was significantly decreased by the serum containing IL-1RA-Ig. CONCLUSIONS: EAM was suppressed by hydrodynamics-based delivery of plasmid DNA encoding IL-1RA-Ig. In addition, IL-1RA-Ig suppressed gene expression of prostaglandin synthases and IL-1 in noncardiomyocytic cells and Th1 cytokines in lymphocytes.

A novel paradigm for therapeutic basis of advanced heart failure--assessment by gene therapy.

The precise mechanism(s) of the progression of advanced heart failure (HF) should be determined to establish strategies for its treatment or prevention. Based on pathological, molecular, and physiological findings in 3 animal models and human cases, we propose a novel scheme that a vicious cycle formed by increased sarcolemma (SL) permeability, preferential activation of calpain over calpastatin, and translocation and cleavage of dystrophin (Dys) commonly lead to advanced HF. The aim of this article was to assess our recent paradigm that disruption of myocardial Dys is a final common pathway to advanced HF, irrespective of its hereditary or acquired origin, but not intended to provide a comprehensive overview of the various factors that may be involved in the course of HF in different clinical settings. In addition, each component of Dys-associated proteins (DAP) was heterogeneously degraded in vivo and in vitro, i.e. Dys and alpha-sarcoglycan (SG) were markedly destroyed using isolated calpain 2, while delta-SG was not degraded at all. The up-regulation of calpain 2 was confirmed through previously published data that remain insufficient for precise evaluation, supporting our new scheme that the activation of calpain(s) is involved in the steady process of Dys cleavage. In addition, somatic gene therapy is discussed as a potential option to ameliorate the physiological/metabolic indices and to improve the prognosis.

Effects of carvedilol on cardiac function and cardiac adrenergic neuronal damage in rats with dilated cardiomyopathy.

UNLABELLED: Metaiodobenzylguanidine (MIBG) is a reliable marker for the detection of cardiac adrenergic neuronal damage in heart failure. The cardioprotective properties of carvedilol, a vasodilating beta-adrenoceptor-blocking agent, were studied in a rat model of dilated cardiomyopathy after autoimmune myocarditis. METHODS: Twenty-eight days after immunization, surviving rats (41/55, or 75%) were divided into 2 groups treated with carvedilol, 2 mg/kg/d (group C, n = 19), or vehicle alone (0.5% methylcellulose, group V, n = 22). After oral administration for 2 mo, heart weight, heart rate, left ventricular end-diastolic pressure (LVEDP), and myocardial fibrosis were measured and compared with those in untreated rats (group N, n = 19). Myocardial uptake of (125)I-MIBG (differential absorption ratio) in the left ventricle was measured by autoradiography at 10, 30, or 240 min after tracer injection. RESULTS: Four (18%) of 22 rats in group V died between days 28 and 84 after immunization. None of the rats in group C or N died. Heart weight, heart rate, LVEDP, and area of myocardial fibrosis in group C (1.14 +/- 0.04 g, 345 +/- 16 beats per minute, 7.6 +/- 1.5 mm Hg, and 12% +/- 1%) were significantly lower than those in group V (1.34 +/- 0.04 g, 389 +/- 10 beats per minute, 12.3 +/- 1.3 mm Hg, and 31% +/- 2%). Although the differential absorption ratio was lower at all time points in group V than in group N, uptake after treatment increased in group C, compared with group V, at 10 min (12.5 +/- 1.0 vs. 7.6 +/- 0.8, not significant), 30 min (10.1 +/- 1.1 vs. 6.3 +/- 0.9, not significant), and 240 min (6.5 +/- 0.5 vs. 2.5 +/- 0.2, P < 0.05). The late washout ratio from myocardial radioactivity between 30 and 240 min in group C was lower than that in group V (36% vs. 60%). CONCLUSION: These observations indicated that carvedilol has beneficial effects and protects cardiac adrenergic neurons in dilated cardiomyopathy.

Fenofibrate, a peroxisome proliferator-activated receptor alpha activator, suppresses experimental autoimmune myocarditis by stimulating the interleukin-10 pathway in rats.

Experimental autoimmune myocarditis (EAM) in rats is an animal model of human giant cell myocarditis and postmyocarditis dilated cardiomyopathy. As the heart consumes large amounts of energy, heart diseases such as myocarditis and dilated cardiomyopathy are associated with abnormal fatty acid metabolism. Peroxisome proliferator-activated receptor alpha (PPARalpha) is a regulator of the oxidative degradation of fatty acids. To investigate the role of PPARalpha in EAM, fenofibrate (a PPARalpha activator) was administered to rats with EAM for 4 weeks. Reductions in the ratios of both ventricular weight to body weight and the area of inflammatory lesions to the total area of heart sections were observed in fenofibrate-treated rats when compared with controls. Fenofibrate ameliorated changes in serum albumin and sialic acid, which are markers of inflammation. Cardiac expression of interleukin-10 (IL-10) mRNA was more pronounced in the fenofibrate group than in the control group (1.3 +/- 0.2 vs 0.7 +/- 0.1; p < 0.01), and the area of intact myocardium correlated with the IL-10 mRNA level (p = 0.0297, r = 0.620). We suggest that PPARalpha activators may prevent the progression of myocarditis through increased expression of the gene encoding the anti-inflammatory cytokine IL-10, although the mechanisms involved remain to be determined.

Insurmountable antagonism of AT-1015, a 5-HT2 antagonist, on serotonin-induced endothelium-dependent relaxation in porcine coronary artery.

The purpose of this study was to examine the inhibitory effects of AT-1015, a newly synthesized 5-HT(2) receptor antagonist, on serotonin-induced endothelium-dependent relaxation in U 46619 (5 x 10(-9)M)-precontracted porcine coronary artery pre-incubated with ketanserin (3 x 10(-6)M), and then compare its effects with another potent 5-HT(2) antagonist, ritanserin. The investigation showed that AT-1015 (10(-8)-10(-6)M) caused rightward shift with significant inhibition of maximum relaxation response induced by serotonin in porcine coronary artery with endothelium. Ritanserin caused a rightward shift of serotonin-induced relaxation without decreasing maximum response at 10(-9) and 10(-8)M, but it inhibited the maximum relaxation response at 10(-7)M. The study showed that AT-1015 and ritanserin had no inhibitory effect on bradykinin-induced relaxation in porcine coronary artery with endothelium. Thus, these findings suggested that AT-1015 at concentrations of 10(-8)-10(-6)M caused noncompetitive blockade of serotonin-induced endothelium-dependent relaxation in porcine coronary artery. The antagonistic effects of AT-1015 on serotonin-induced relaxation were different from that of ritanserin, except at 10(-7)M ritanserin. The variation of inhibitory effects between these two 5-HT(2) antagonists may be due to the different chemical structure and/or interaction sites at the receptor.

AT-1015, a newly synthesized 5-HT2 receptor antagonist, dissociates slowly from the 5-HT2 receptor sites in rabbit cerebral cortex membrane.

The purpose of this study was to investigate the association and dissociation kinetics of [3H]AT-1015 from 5-HT2 receptors in rabbit cerebral cortex membranes using a radioligand binding assay method and to make a comparison with those of [3H]ketanserin binding. Scatchard analysis of [3H]AT-1015 binding in rabbit cerebral cortex membranes indicated the existence of a single class of binding sites (dissociation constant, Kd = 2.18 nM). The specific binding of [3H]AT-1015 increased slowly with time and the association rate constant of [3H]AT-1015 binding (k1 = 0.1229 min-1 nM-1) was two times slower than that of [3H]ketanserin binding (k1 = 0.2451 min-1 nM-1). The dissociation rate constant of [3H]AT-1015 binding (t 1/2 = 37.03 min) was six times slower than that of [3H]ketanserin binding (t 1/2 = 6.29 min), when the addition of excess unlabelled ligands were AT-1015 and ketanserin, respectively. The dissociation rate constant of [3H]AT-1015 was slowed to a greater degree (t 1/2 = 163.40 min and t 1/2 = 198.12 min) by the addition of ketanserin and sarpogrelate as excess unlabelled ligands than was that of [3H]ketanserin (t 1/2 = 17.76 min and t 1/2 = 18.45 min) by the addition of AT-1015 and sarpogrelate as an excess unlabelled ligand, respectively. These findings on the dissociation kinetics of [3H]AT-1015 have confirmed and supported previously reported evidence of the slower dissociation of AT-1015 from 5-HT2 receptors.

Sarcolemmal fragility secondary to the degradation of dystrophin in dilated cardiomyopathy, as estimated by electron microscopy.

A common gene deletion or mutation of delta-sarcoglycan (delta-SG) in dystrophin-related proteins (DRPs) is identified in both TO-2 strain hamsters and human families with dilated cardiomyopathy. We have succeeded in the long-lasting in vivo supplementation of a normal delta-SG gene by recombinant adeno-associated virus vector, restoration of the morphological and functional degeneration, and improvement in the prognosis of the TO-2 hamster. To evaluate the integrity of the sarcolemma (SL) and the subsequent change of organelles in cardiomyocytes of the TO-2 strain hamster, we examined electron microscopy (EM) images focusing on the sarcolemmal stability at the end stage of heart failure. Two types of sarcolemmal degradation were detected: the widened and locally thickened SL, and blurred and discontinuous SL. Bizarrely formed mitochondria of varying sizes were also observed. Immuno-EM revealed clear expression of dystrophin in the SL and intense expression at the costamere as well as at the T-tubules in the control F1B strain hearts, but a patchy deposition of dystrophin was observed along the SL without the transgene of delta-SG. In contrast to the previous reports that dystrophin's integrity was intact, the present results suggest that the gene deletion of delta-SG and the loss of delta-SG protein in the SL cardioselectively cause the morphological and functional deterioration of dystrophin and the resultant instability of the SL. The sarcolemmal fragility may be similar to Duchenne-type progressive muscular dystrophy in skeletal muscle. In addition to the mechanical role, another aspect of DRPs for the intracellular signal transmission is also discussed.

Suppression of myocardial ischemia-reperfusion injury by inhibitors of cytochrome P450 in rats.

The effects of inhibitors of cytochrome P450 on myocardial regional ischemia-reperfusion injury were examined in rats. Ischemia-reperfusion injury was evoked by ligation of the left anterior descending coronary artery for 1 h, followed by reperfusion for 24 h. Injuries were evident in causing infarction, decreases in left ventricular systolic pressure and left ventricle (dP/dt max)/P and an increase in left ventricular end-diastolic pressure. Increases in lipid peroxidation and reactive oxygen species levels in the ischemic region were observed. Intravenous injection of the potent cytochrome P450 inhibitor sulfaphenazole at 10 and 30 mg/kg at the time of reperfusion reduced infarct size by 41.7 and 73.2%, respectively; and improved cardiac function accompanied by the decrease in content of lipid peroxide and reactive oxygen species in the area at risk. Cardiac testosterone metabolism was inhibited by sulfaphenazole administration, indicating its inhibitory effects on cardiac cytochrome P450 activity. Another cytochrome P450 inhibitor, cimetidine, given intravenously, had similar effects to sulfaphenazole on reperfusion injury. Taken together, these results indicate that reactive oxygen species derived from cytochrome P450 play an important part in myocardial regional ischemia-reperfusion injury in vivo, and strongly support the hypothesis that cytochrome P450 inhibitors are promising therapeutic agents for cardiac ischemia-reperfusion injury.

Preparation of polycarboxylic acids by oxidative cleavage with oxygen / Co-Mn-Br system.

Adipic acid and glutaric acid were obtained from 1-hydroxy-2- acetoxycyclohexane by oxidation cleavage using molecular oxygen in the presence of cobalt acetate, manganese acetate and hydrobromic acid in acetic acid solution. Applying this method to prepare dicarboxylic acids from unsaturated fatty acids, we proposed an efficient method where reaction mixture of unsaturated fatty acids and hydrogen peroxide - formic acid can be oxidative cleaved to produce dicarboxylic acids and monocarboxylic acids in acetic acid solution with molecular oxygen / Co-Mn-Br system. For example, azelaic acid, suberic acid and other dicarboxylic acid as dicarboxylic acids were obtained from industrial oleic acid, which contained oleic acid, palmitoleic acid, linoleic acid, and linolenic acid. As a result of investigation for reaction condition, increase of partial pressure of molecular oxygen or elevation of temperature accelerated oxidative cleavage, but total yields of azelaic acid and suberic acid were slightly decreased. Besides, effect of hydrohalic acids in liquid phase air oxidation in the presence of cobalt and manganese acetates was investigated to show that HBr was the most effective. Soybean acid and tall acid containing higher amounts of linoleic acid and linolenic acid than industrial oleic acid were also oxidatively cleaved to dicarboxylic acids.

Differential inhibition by oxygen radicals of vasoactive amines-induced contractions in the porcine coronary artery.

Reactive oxygen species (ROS) play an important role in normal metabolic and signaling processes. Excess ROS, however, can cause severe cardiovascular damage. Thus, the present study was designed to examine effects of H(2)O(2) and xanthine plus xanthin oxidase (X/XO) on the serotonin (5HT), histamine (His) and acetylcholine (ACh)-induced contractions of porcine coronary arteries. In addition, to explore the site of ROS formation and species of it, the inhibitory effects of edaravone and EDTA were also tested. 5HT- and His-induced contractions were suppressed by H(2)O(2) and X/XO treatment. However, these suppressions of ACh-induced contraction by H(2)O(2) treatment was relatively weak and X/XO treatment caused no suppression on ACh-induced contraction. In the presence of edaravone which is thought to be a scavenger for .OH, significant decrease of inhibition of 5HT- and His-induced contractions was observed when coronary artery strips were treated with X/XO, but not H(2)O(2). On the other hand, inhibitory effects by EDTA treatments were also observed in X/XO treatments. These results suggest that 1) ROSs produced by additions of H(2)O(2) or X/XO are considered to be responsible for several physiological functions of coronary artery contractions, 2) the site of ROS produced by X/XO system, probably .OH, was outside the cell, but the inhibitory action of H(2)O(2), was inside the cell, and 3) a low susceptibility of ACh-induced contraction to H(2)O(2) and X/XO may indicates the signal transduction pathway(s) of ACh-induced contraction is different from those of 5HT and His.

Cardioprotective effects of recombinant human erythropoietin in rats with experimental autoimmune myocarditis.

Erythropoietin (EPO) has been known to have cytoprotective effects on several types of tissues, presumably through modulation of apoptosis and inflammation. The effect of EPO on myocardial inflammation, however, has not yet been clarified. We investigated the cardioprotective effects of EPO in rats with experimental autoimmune myocarditis (EAM). Seven-week-old Lewis rats immunized with cardiac myosin were treated either with EPO or vehicle and were examined on day 22. EPO attenuated the functional and histological severity of EAM along with suppression of mRNAs of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 in the hearts as well as a reduction of apoptotic cardiomyocytes. The EPO receptor (EPO-R) was upregulated in the myocardium of EAM compared with that of healthy rats. These results may suggest that EPO ameliorated the progression of EAM by modulating myocardial inflammation and apoptosis.