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Cytoprotective effects of nitrite during in vivo ischemia-reperfusion of the heart and liver.

Nitrite represents a circulating and tissue storage form of NO whose bioactivation is mediated by the enzymatic action of xanthine oxidoreductase, nonenzymatic disproportionation, and reduction by deoxyhemoglobin, myoglobin, and tissue heme proteins. Because the rate of NO generation from nitrite is linearly dependent on reductions in oxygen and pH levels, we hypothesized that nitrite would be reduced to NO in ischemic tissue and exert NO-dependent protective effects. Solutions of sodium nitrite were administered in the setting of hepatic and cardiac ischemia-reperfusion (I/R) injury in mice. In hepatic I/R, nitrite exerted profound dose-dependent protective effects on cellular necrosis and apoptosis, with highly significant protective effects observed at near-physiological nitrite concentrations. In myocardial I/R injury, nitrite reduced cardiac infarct size by 67%. Consistent with hypoxia-dependent nitrite bioactivation, nitrite was reduced to NO, S-nitrosothiols, N-nitros-amines, and iron-nitrosylated heme proteins within 1-30 minutes of reperfusion. Nitrite-mediated protection of both the liver and the heart was dependent on NO generation and independent of eNOS and heme oxygenase-1 enzyme activities. These results suggest that nitrite is a biological storage reserve of NO subserving a critical function in tissue protection from ischemic injury. These studies reveal an unexpected and novel therapy for diseases such as myocardial infarction, organ preservation and transplantation, and shock states.

Animals↗

Myocardial cytoprotection by trimetazidine against anthracycline-induced cardiotoxicity in anticancer chemotherapy.

The ability of trimetazidine (2,3,4, trimethoxybenzylpiperazine dihydrochloride, TMZ) to protect the myocardium against anthracycline (ANT)-induced cardiotoxicity during chemotherapy has been evaluated in female patients with breast cancer. A clinical trial was conducted in 61 patients subdivided into three groups: group 1 (n = 15, G1 ) treated with standard ANT protocol and cardioprotection by dexrazoxane (DEX) plus TMZ (60 mg, daily dose); group 2 (n = 22, G2) treated with ANT and cardioprotection by TMZ only; and group 3 (n = 24, G3) scheduled to receive ANT therapy and DEX. All the patients submitted to an echocardiographic evaluation of diastolic function (E wave velocity, A wave velocity, isovolumetric relaxation time [IVRT], deceleration time [DT]) at enrollment (T0), at T1 time, at T2 time, and at T3 time. After a 12-month follow-up period, the patients showed a good conservation of diastolic function both in G1 and G2 groups. No statistically significant difference was observed in E wave and A wave velocity and E/A ratio after ANT treatment. TMZ produced a cardioprotective effect, comparable to DEX protection, against subacute and chronic subclinical cardiotoxicity with no significant changes in diastolic function after 1 year of follow-up.

Aged↗

Cytoprotective effects of epidermal growth factor (EGF) ointment containing nafamostat, a protease inhibitor, on tissue damage at burn sites in rats.

When epidermal growth factor (EGF) ointment containing a protease inhibitor, nafamostat (NM), was applied to burn sites in rats, the superoxide dismutase (SOD) enzyme activity and protein content increased 45% and 60%, respectively, at these sites 1 d after the burns compared with the control ointment. Following treatment with EGF plus NM (EGF + NM) ointment, messenger RNA for SOD also increased, to about 1.6 times that of the control at 1 d after the burn, indicating that this ointment stimulates SOD synthesis at burn sites in vivo. In contrast, following treatment with EGF + NM ointment, the content of heat shock protein (HSP 70) in the burned tissue decreased to about 70% of the control value 1 d after the burn. These findings suggest that EGF + NM ointment alleviated tissue damage at burn sites at an early stage, and that this was related to the stimulation of SOD synthesis and reduced HSP 70 levels. We also examined the effects of SOD ointment on wound healing at burn sites. A dose-dependent increase in the dry weight of granulation tissue at wound sites 3 d after the burn was observed following the application of this ointment. These results suggest that SOD may play an important role in wound healing after burns.

Animals↗

Cytoprotective and cytotoxic effects of curcumin: dual action on H2O2-induced oxidative cell damage in NG108-15 cells.

The ability of curcumin, a natural antioxidant isolated from Curcuma longa, to inhibit hydrogen peroxide (H(2)O(2))-induced cell damage in NG108-15 cells was examined. When added simultaneously with 500 microM H(2)O(2), curcumin (25-100 microM) effectively protected cells from oxidative damage. However, when the cells were pretreated with curcumin (25-100 microM) for 1.5 h before H(2)O(2) exposure, curcumin was unable to inhibit H(2)O(2)-induced cell damage. Instead, it caused a significant concentration-dependent decrease in cell viability after H(2)O(2) exposure. This dual action of curcumin suggests that pretreatment with curcumin by itself did not have any significant effect on the viability of the NG108-15 cells, but it sensitized them to oxidative damage induced by H(2)O(2) under our experimental conditions. It appears that these events may not relate to the antioxidant and free radical scavenging activities of curcumin.

Animals↗

Cytoprotective effects of nicorandil on hypothermic injury to immature cardiac myocytes--comparison with nitroglycerin, diltiazem and prostaglandin E1.

The purpose of this study was to evaluate the functional and biochemical effects of nicorandil (NRD), nitroglycerin (NTG), diltiazem (DTZ) and prostaglandin E1 (PGE) on cardiac myocytes incubated under hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 107 medium. Myocytes (12.5 x 10(5) myocytes/flask) were then incubated at 4 degrees C for 24 h in media containing various concentrations of NRD, NTG, DTZ or PGE. After hypothermic incubation, creatine kinase (CK) and lactate dehydrogenase (LDH) were measured. The myocytes were cultured for an additional 24 h at 37 degrees C to evaluate the recovery of myocyte beating rate. In the nicorandil groups, 10(-4) M NRD showed a significantly increased beating rate recovery compared to the control (44% vs 25% respectively, as a percentage of the baseline values; i.e., beating rate prior to hypothermic incubation). Although treatment with 10(-6) M diltiazem showed no beneficial effects (10(-6) M; 25%, control; 30%), beating was not observed at all with 10(-4) M or 10(-5) M DTZ. There were no significant changes among the NTG and PGE groups. The release of CK and LDH was significantly suppressed with 10(-4) M NRD (10(-4) M: 24.1 mIU/flask, 257.2; control: 125.4, 459.5, respectively). In contrast, 10(-4) M DTZ showed significantly increased CK and LDH levels compared to its respective control (10(-4) M: 203.3 mIU/flask, 883.4; control: 112.3, 457.4, respectively). There were no significant differences in CK and LDH levels among the NTG and PGE groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗

Cytoprotective effects of NC-1300 and omeprazole on Hcl . ethanol-induced gastric lesions in rats.

NC-1300 (10-100 mg/kg), given p.o. at 0.5, 6, 12 or 24 hr before HCl . ethanol, dose-dependently protected the rat gastric mucosa. This protection was observed even when the gastric contents had been removed before application of HCl . ethanol. NC-1300 (30 mg/kg), given i.p., was without effect on lesion formation in a dose which potently inhibited gastric acid secretion in pylorus-ligated rats. pretreatment with indomethacin (5 mg/kg, s.c.) resulted in no reduction in the protection by NC-1300, excluding the possible participation of endogenous prostaglandins in the protective mechanism. N-ethylmaleimide pretreatment (10 mg/kg, s.c.) slightly reduced the protective activity of NC-1300, suggesting the partial participation of endogenous sulfhydryl compounds in the NC-1300 protection. NC-1300 sulfide and mercaptobenzimidazole (compounds obtained after mixing NC-1300 with acidic solution) also dose-dependently protected against HCl . ethanol-induced lesions when given p.o. at 0.5 hr before HCl . ethanol. The protection was significant but was considerably reduced in contrast to NC-1300 when the compounds were given 12 hr beforehand. NC-1300 sulfone had no effect on lesion formation. Omeprazole (10, 30 mg/kg), given p.o., also dose-dependently inhibited HCl . ethanol-induced lesions. However, the duration of protection was shorter than that seen with NC-1300, i.e., the effect disappeared 12 hr later. Thus, NC-1300 has a potent and long-lasting activity on HCl . ethanol-induced gastric lesions. The mechanism by which this occurs remains unknown.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Dissolution of antisecretory and cytoprotective action of PGE2 in rats.

Oral administration of 60% ethanol in 150 mM HCl (HCl.ethanol) to rats produced gastric mucosal lesions within 1 hr. PGE2 given s.c. at 0.1 to 3 mg/kg 0.5 hr before HCl.ethanol significantly prevented the lesion formation. The protection afforded with 3 mg/kg of PGE2 persisted for 6 or 12 hr after administration. PGE2 given s.c. at 3 mg/kg significantly inhibited gastric secretion in pylorus-ligated and intact rats, but the action disappeared 6 hr later.

Animals↗

Cytoprotective effect of plasmin inhibitor on necrotizing agent-induced gastric lesions in rats.

We studied the effect of plasmin inhibitor on ethanol and ammonia-induced gastric mucosal lesions in rats using an ex vivo chamber. Tranexamic acid and aminocaproic acid significantly inhibited macroscopic gastric hemorrhagic necrosis and attenuated the decrease of gastric transmucosal potential difference induced by 50% ethanol and 1% ammonia. The protection of gastric mucosa afforded by tranexamic acid and aminocaproic acid was not affected by pretreatment with indomethacin (5 mg/kg). These results suggest that plasmin inhibitor plays an important role in the prevention of gastric deep necrosis following exposure of the stomach to a damaging agent.

Aminocaproic Acid↗

Cytoprotective effect of 3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY-9760e) against ischemia/reperfusion-induced injury in rat heart involves inhibition of fodrin breakdown and protein tyrosine nitration.

We here assessed the effects of 3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY-9760e), a novel calmodulin antagonist, on infarct size in the rat heart subjected to ischemia/reperfusion. Rats were subjected to a 30-min coronary occlusion followed by a 24-h reperfusion. DY-9760e was intravenously infused for 20 min, starting at 20 min after coronary occlusion. Treatment with DY-9760e (10 mg/kg) significantly reduced the infarct size in the risk area assessed by Evans Blue/TTC (triphenyltetrazolium chloride) staining. DY-9760e treatment also ameliorated contractile dysfunction of the left ventricle 72 h after reperfusion. DY-9760e significantly inhibited fodrin breakdown and caspase-3 activation. The inhibitory effect of DY-9760e on the fodrin breakdown was prominent in the rim rather than in the center of the risk area. DY-9760e also blocked protein tyrosine nitration associated with infarction. These results suggest that the cardioprotective effect of DY-9760e involved inhibition of calpain/caspase activation and protein tyrosine nitration.

Animals↗

Self-cytoprotection against stress: feedback regulation of heme-dependent metabolism.

This minireview provides insight into feedback regulation of heme-dependent metabolism as a defensive cellular response against stress. Interactions among heme-, iron-, porphyrin-, and CO/NO-dependent metabolic pathways during the stress-induced response are emphasized in the context of feedback regulation. The hypothetical model of the latter interactions is presented as tightly controlled feedback cycles.

Animals↗

Distribution, phosphorylation, and activities of Hsp25 in heat-stressed H9c2 myoblasts: a functional link to cytoprotection.

The behavior of the endogenous heat shock protein 25 (Hsp25) in heat-stressed rat H9c2 myoblasts was studied. After mild or severe heating, this protein became less extractable with Triton X-100 and displayed characteristic immunofluorescence patterns, namely (1) granules in the nucleus, and (2) association with F-actin bundles in the cytoplasm. The intranuclear granulation of Hsp25 and its association with F-actin were sensitive to drugs affecting Hsp25 phosphorylation (cantharidin, sodium orthovanadate, SB203580, SB202190). Isoform analysis of Hsp25 translocated to the nucleus-free cytoskeletal fraction revealed only mono- and biphosphorylated Hsp25 and no unphosphorylated Hsp25. Transfected luciferase with initial localization in the nucleosol became colocalized with the Hsp25-containing granules after a heat shock treatment that denatured the enzyme in the cells. The association of Hsp25 with actin filaments after a mild heat stress conferred protection from subsequent F-actin-damaging treatments with cytochalasins (D and B) or severe heat stress. We hypothesize that (1) the binding of heat-denatured nucleosolic proteins to the Hsp25 contained in specific granular structures may serve for the subsequent chaperoning or degradation of the bound proteins, and (2) the actin cytoskeleton is stabilized by the direct targeting of phosphorylated Hsp25 to microfilament bundles.

Animals↗

Expression of cytoprotective proteins, heat shock protein 70 and metallothioneins, in tissues of Ostrea edulis exposed to heat and heavy metals.

Heat shock proteins (Hsps) are constitutively expressed in cells and involved in protein folding, assembly, degradation, intracellular localization, etc, acting as molecular chaperones. However, their overexpression represents a ubiquitous molecular mechanism to cope with stress. Hsps are classified into families, and among them the Hsp70 family appears to be the most evolutionary preserved and distributed in animals. In this study, the expression of Hsp70 and the related messenger ribonucleic acid (mRNA) has been studied in Ostrea edulis after exposure to heat and heavy metals; moreover, levels of metallothioneins (MTs), another class of stress-induced proteins, have contemporaneously been assessed in the same animals. Thermal stress caused the expression of a 69-kDa inducible isoform in gills of O edulis but not in the digestive gland. Northern dot blot analysis confirmed that the transcription of Hsp69-mRNA occurs within 3 hours of stress recovery after oyster exposure at 32 and 35 degrees C. Hsp69-mRNA transcripts were not present in the gills of animals exposed to 38 degrees C after 3 hours of poststress recovery, but they were detected after 24 hours. The expression of the 69-kDa protein in O edulis exposed to 38 degrees C was rather low or totally absent, suggesting that the biochemical machinery at the base of the heat shock response is compromised. Together with the expected increase in MT content, the oysters exposed to Cd showed a significant enhancement of Hsp70, although there was no clear appearance of Hsp69. Interestingly, the levels of MT were significantly increased in the tissues of individuals exposed to thermal stress. Unlike oysters, heat did not provoke the expression of inducible Hsp isoforms in Mytilus galloprovincialis, Tapes philippinarum, and Scapharca inaequivalvis, although it significantly enhanced the expression of constitutive proteins of the 70-kDa family. The expression of newly synthesized Hsp70 isoforms does not seem therefore a common feature in bivalves exposed to thermal stress.

Animals↗

Gender difference in cytoprotection induced by estrogen on female and male bovine aortic endothelial cells.

Before menopause, women have a lower risk of cardiovascular diseases than men. Studies attribute this gender difference to estrogenic protection in the female cardiovascular system. We have demonstrated that 17beta-estradiol (E2) protects female bovine aortic endothelial cells against oxidative injury, probably through the induction of antioxidant enzyme activities. In this study, we examined whether E2 confers a differential protection on male and female cells. Bovine aortic endothelial cells from both genders were preconditioned for 24 h with E2 (1 nM to 10 microM), and their resistance to paraquat (1 mM, 3 h), a superoxide generator, was measured using an MTT assay. In contrast to the protection observed in female bovine aortic endothelial cells, there was no protective effect by E2 on male bovine aortic endothelial cells at physiologic concentrations. However, E2 at 1-10 microM attenuated paraquat's toxicity in both male and female cells, probably through its direct antioxidant activity. E2 at 1 nM increased in female, but not in male, cells the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, which was associated with decreased levels of reactive oxygen species during subsequent paraquat exposure. This suggests that antioxidant enzyme induction plays some role in E2-augmented oxidative resistance in female endothelial cells.

Animals↗

Hypoxic preconditioning: a novel intrinsic cytoprotective strategy.

A concept of tissue-cell adaptation to hypoxia (hypoxic preconditioning) is raised and its corresponding animal model is introduced. A significantly strengthened tolerance to hypoxia and a protective effect of the brain extracts from the preconditioned animals are presented. Changes in animals' behavior, neuromorphology, neurophysiology, neurochemistry and molecular neurobiology during preconditioning are described. Energy saving, hypometabolism, and cerebral protection in particular are thought to be involved in the development of hypoxic tolerance and tissue-cell protection. The essence and significance of the hypoxic tissue-cell adaptation or preconditioning are discussed in terms of biological evolution and practical implication.

Animals↗

Cytoprotection of heme oxygenase-1/carbon monoxide in lung injury.

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) have been the major cause of morbidity and mortality in intensive care units (ICU) over the past decades despite advances in therapeutic modalities. This syndrome is characterized by noncardiogenic pulmonary edema, and pulmonary and systemic inflammation resulting in respiratory failure (1, 2). Both exudative and proliferative organizing phases of ARDS/ALI have been described pathologically (3, 4). The exudative phase is often called diffuse alveolar damage (DAD) characterized by inflammation and hyaline membrane composed of fibrin and cellular debris (3--5). Pulmonary alveolar cell death is the major pathologic change during the exudative phase in DAD. Repair and remodeling of injured lung cells occur during the proliferative phase, characterized by hyperplasia of alveolar type II cells and fibroblast proliferation (3-5). A variety of cellular insults can cause ALI/ARDS including but not limited to sepsis, trauma, drugs, high concentration of oxygen therapy, and mechanical ventilation (1, 2, 5). The broad spectrum of insults that potentially cause ARDS highlights the complexity of pathogenesis of this syndrome.

Animals↗