Background: Myocardial ischemia-reperfusion represents a clinically relevant problem associated with thrombolysis, angioplasty and coronary bypass surgery. Injury of myocardium due to ischemia-reperfusion includes cardiac contractile dysfunction, arrhythmias as well as irreversible myocyte damage. These changes are considered to be the consequence of imbalance between the formation of oxidants and the availability of endogenous antioxidants in the heart. Observations: An increase in the formation of reactive oxygen species during ischemia-reperfusion and the adverse effects of oxyradicals on myocardium have now been well established by both direct and indirect measurements. Although several experimental studies as well as clinical trials have demonstrated the cardioprotective effects of antioxidants, some studies have failed to substantiate the results. Nonetheless, it is becoming evident that some of the endogenous antioxidants such as glutathione peroxidase, superoxide dismutase, and catalase act as a primary defense mechanism whereas the others including vitamin E may play a secondary role for attenuating the ischemia-reperfusion injury. The importance of various endogenous antioxidants in suppressing oxidative stress is evident from the depression in their activities and the inhibition of cardiac alterations which they produce during ischemia-reperfusion injury. The effects of an antioxidant thiol containing compound, N-acetylcysteine, and ischemic preconditioning were shown to be similar in preventing changes in the ischemic-reperfused hearts. Conclusions: The available evidence support the role of oxidative stress in ischemia-reperfusion injury and emphasize the importance of antioxidant mechanisms in cardioprotection.

Cholesteryl ester transfer protein (CETP) is the enzyme that facilitates the transfer of cholesteryl ester from high density lipoprotein (HDL) to apolipoprotein B (apoB)-containing lipoproteins. However, the exact role of CETP in the development of atherosclerosis has not been determined. In the present study, we examined the effect of the suppression of increased plasma CETP by intravenous injection with antisense oligodeoxynucleotides (ODNs) against CETP targeted to the liver on the development of atherosclerosis in rabbits fed a cholesterol diet. The ODNs against rabbit CETP were coupled to asialoglycoprotein (ASOR) carrier molecules, which serve as an important method to regulate liver gene expression. Twenty-two male Japanese White rabbits were used in the experiment. Eighteen animals were fed a standard rabbit chow supplemented with 0.3% cholesterol throughout the experiment for 16 weeks. At 8 weeks, they were divided into three groups (six animals in each group), among which the plasma total and HDL cholesterol concentrations did not significantly change. The control group received nothing, the sense group were injected with the sense ODNs complex, and the antisense group were injected with the antisense ODNs complex, respectively, for subsequent 8 weeks. ASOR⅐poly(L-lysine) ODNs complex were injected via the ear veins twice a week. Four animals were fed a standard rabbit diet for 16 weeks. The total cholesterol concentrations and the CETP mass in the animals injected with antisense ODNs were all significantly decreased in 12 and 16 weeks compared with those injected with sense ODNs and the control animals. The HDL cholesterol concentrations measured by the precipitation assay did not significantly change among the groups fed a cholesterol diet, and triglyceride concentrations did not significantly change in the four groups. However, at the end of the study, when the HDL cholesterol concentrations were measured after the isolation by ultracentrifugation and a column chromotography, they were significantly higher in the animals injected with antisense ODNs than in the animals injected with sense ODNs and in the control animals. A reduction of CETP mRNA and an increase of LDL receptor mRNA in the liver were observed in the animals injected with antisense ODNs compared with those injected with sense ODNs and the control animals. Aortic cholesterol contents and the aortic percentage lesion to total surface area were significantly lower in the animals injected with antisense ODNs than in the animals injected with sense ODNs and in the control animals. These findings showed for the first time that suppression of increased plasma CETP by the injection with antisense ODNs against CETP coupled to ASOR carrier molecules targeted to the liver could thus inhibit the atherosclerosis possibly by decreasing the plasma LDL ؉ very low density lipoprotein (VLDL) cholesterol in cholesterol-fed rabbits. Cholesteryl ester transfer protein (CETP)1 is a plasma glycoprotein that catalyzes the transfer of cholesteryl ester and tr...

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Heart sarcolemmal membranes were isolated by the sucrose density gradient method from rats with chronic diabetes induced by a streptozotocin (65 mg/kg iv) injection. Na+-dependent Ca2+-uptake activities were significantly depressed in diabetic sarcolemmal membranes; such alterations were evident at different incubation times and at different concentrations of Ca2+. Administration of insulin to diabetic rats normalized the Na+-dependent Ca2+-uptake activities. ATP-dependent Ca2+ accumulation and Ca2+-stimulated Mg2+-dependent ATPase, which represents Ca2+-pump mechanisms, were significantly depressed in sarcolemmal preparations for diabetic rats and these changes were also reversible upon insulin treatment. An increase in lysophosphatidylcholine and a decrease in phosphatidylethanolamine as well as diphosphatidylglycerol contents were observed in heart membranes isolated from diabetic rats but other phospholipids were unchanged. Cholesterol-to-phospholipid ratio was significantly increased in preparations from diabetic rats. These results indicate a depression in the ability of the cell to remove Ca2+ through Na+-Ca2+ exchange and Ca2+-pump mechanisms in sarcolemma, and these defects may contribute to the occurrence of intracellular Ca2+ overload and diabetic cardiomyopathy.

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Lipid peroxidation due to oxidative stress (OS) may play an important role in the pathogenesis of chronic systemic inflammatory diseases such as multiple sclerosis (MS). Telomeres, repeated sequences that cap chromosome ends, undergo shortening with each cycle of cell division, resulting in cellular senescence. Research regarding telomere shortening has provided novel insight into the pathogenesis of various diseases. We hypothesized that OS damage leads to inflammatory reactions, which subsequently shortens the telomere length in MS. We enrolled 59 patients with MS, and age- and gender-matched 60 healthy controls. We divided MS subjects into three groups matched for age and gender according to the severity of disability: relatively benign course (BMS), secondary progressive MS, and primary progressive MS (PPMS). We analyzed the telomere length in peripheral blood mononuclear cells and the 8-iso-PGF2α concentration in urine, a reliable and stable marker of lipid peroxidation in vivo. The data showed significant higher levels of urinary 8-iso-PGF2α in MS subjects than in the controls. The lag-time, which represents the direct measurement of the resistance of low-density lipoprotein to oxidation, was shorter in the PPMS subjects than in the groups. Compared to that observed in the controls, the mean telomere length was significantly shorter in the PPMS group, whereas no significant telomere shortening was found between the controls and other subjects. Our data suggest that a decreased telomere length and enhanced lipid peroxidation reflects the severest stage of MS.

Transient receptor potential (TRP) proteins have been identified as cation channels that are activated by agonist-receptor coupling and mediate various cellular functions. TRPC7, a homologue of TRP channels, has been shown to act as a Ca2+ channel activated by G protein-coupled stimulation and to be abundantly expressed in the heart with an as-yet-unknown function. We studied the role of TRPC7 in G protein-activated signaling in HEK293 cells and cultured cardiomyocytes in vitro transfected with FLAG-tagged TRPC7 cDNA and in Dahl salt-sensitive rats with heart failure in vivo. TRPC7-transfected HEK293 cells showed an augmentation of carbachol-induced intracellular Ca2+ transient, which was attenuated under a Ca2+-free condition or in the presence of SK&F96365 (a Ca2+-permeable channel blocker). Upon stimulation with angiotensin II (Ang II), cultured neonatal rat cardiomyocytes transfected with TRPC7 exhibited a significant increase in apoptosis detected by TUNEL staining, accompanied with a decrease in the expression of atrial natriuretic factor and destruction of actin fibers, as compared with non-transfected cardiomyocytes. Ang II-induced apoptosis was inhibited by CV-11974 (Candesartan; Ang II type 1 [AT1] receptor blocker), SK&F96365, and FK506 (calcineurin inhibitor). In Dahl salt-sensitive rats, apoptosis and TRPC7 expression were increased in the failing myocardium, and a long-term treatment with temocapril, an angiotensin-converting enzyme inhibitor, suppressed both. Our findings suggest that TRPC7 could act as a Ca2+ channel activated by AT1 receptors, leading to myocardial apoptosis possibly via a calcineurin-dependent pathway. TRPC7 might be a key initiator linking AT1-activation to myocardial apoptosis, and thereby contributing to the process of heart failure.

Telomeres are the repeated sequences at the chromosome ends which undergo shortening with cell division. The telomere shortening of the peripheral leukocytes is also facilitated by enhanced oxidative stress in various kinds of disease including ischemic heart disease, diabetes mellitus, apoplexy, and Alzheimer's disease. Telomere shortening in Parkinson's disease (PD) has not yet been reported. The pathogenesis for PD is also regarded to be associated with oxidative stress. We investigated 28 Japanese male PD patients ages 47-69. Although we could not find a statistical difference in the mean telomere length of peripheral leukocytes between the PD patients and the control participants, we found the mean telomere lengths to be shorter than 5 kb in only the PD patients and a significant PD-associated decrease in the telomeres with a length ranging from 23.1 to 9.4 kb in the patients in their 50s and 60s. These observations suggest that telomere shortening is accelerated in PD patients in comparison to the normal population.