Omega-3 fatty acids reduce lipopolysaccharide-induced abnormalities in expression of connexin-40 in aorta of hereditary hypertriglyceridemic rats.

Omega-3 fatty acids (omega3FA) are known to reduce hypertriglyceridemia- and inflammation-induced vascular wall diseases. However, mechanisms of their effects are not completely clear. We examined, whether 10-day omega3FA diet can reduce bacterial lipopolysaccharide-induced changes in expression of gap junction protein connexin40 (Cx40) in the aorta of hereditary hypertriglyceridemic (hHTG) rats. After administration of a single dose of lipopolysaccharide (LPS, 1 mg/kg, i.p.) to adult hHTG rats, animals were fed with omega3FA diet (30 mg/kg/day) for 10 days. LPS decreased Cx40 expression that was associated with reduced acetylcholine-induced relaxation of aorta. Omega3FA administration to LPS rats had partial anti-inflammatory effects, associated with increased Cx40 expression and improved endothelium dependent relaxation of the aorta. Our results suggest that 10-day omega3FA diet could protect endothelium-dependent relaxation of the aorta of hHTG rats against LPS-induced damage through the modulation of endothelial Cx40 expression.

Modulation of cardiac connexin-43 by omega-3 fatty acid ethyl-ester supplementation demonstrated in spontaneously diabetic rats.

Previous data suggest that type 1 diabetes mellitus leads to the deterioration of myocardial intercellular communication mediated by connexin-43 (Cx43) channels. We therefore aimed to explore Cx43, PKC signaling and ultrastructure in non-treated and omega-3 fatty acid (omega-3) treated spontaneously diabetic Goto-Kakizaki (GK) rats considered as type 2 diabetes model. Four-week-old GK and non-diabetic Wistar-Clea rats were fed omega-3 (200 mg/kg/day) for 2 months and compared with untreated rats. Real-time PCR and immunoblotting were performed to determine Cx43, PKC-epsilon and PKC-delta expression. In situ Cx43 was examined by immunohistochemistry and subcellular alterations by electron microscopy. Omega-3 intake reduced blood glucose, triglycerides, and cholesterol in diabetic rats and this was associated with improved integrity of cardiomyocytes and capillaries in the heart. Myocardial Cx43 mRNA and protein levels were higher in diabetic versus non-diabetic rats and were further enhanced by omega-3. The ratio of phosphorylated (functional) to non-phosphorylated Cx43 was lower in diabetic compared to non-diabetic rats but was increased by omega-3, in part due to up-regulation of PKC-epsilon. In addition, pro-apoptotic PKC-delta expression was decreased. In conclusion, spontaneously diabetic rats at an early stage of disease benefit from omega-3 intake due to its hypoglycemic effect, upregulation of myocardial Cx43, and preservation of cardiovascular ultrastructure. These findings indicates that supplementation of omega-3 may be beneficial also in the management of diabetes in humans.

The effect of omega-3 fatty acids on expression of connexin-40 in Wistar rat aorta after lipopolysaccharide administration.

Connexin (Cx)-channels can represent one of targets of omega-3 fatty acids (n-3 PUFA) in protection of cardiovascular system against injury. We investigated the anti-inflammatory effect of 10-day n-3 PUFA intake (30 mg/kg/day for 10 days) on expression of Cx40 isoform in the aorta of Wistar rats injected with a single dose of lipopolysaccharide (LPS, 1 mg/kg, i.p.). LPS resulted in up-regulation of Cx40 expression in the aorta associated with reduced endothelium-dependent relaxation. LPS increased levels of inflammatory markers C-reactive protein and malondialdehyde in circulation as well as NOS activity and CD68 expression in aortic tissue indicating presence of moderate inflammation. N-3 PUFA supplementation decreased expression of both Cx40 and CD68 in aortic tissue and suppressed concentrations of C-reactive protein and malondialdehyde of endotoxemic rats. N-3 PUFA did not improve NO-dependent relaxation of aorta and NOS activity in LPS rats. The results indicate the involvement of Cx40 in development of LPS-induced endothelium-dependent functional impairment of the aorta and partial health benefits of n-3 PUFA diet associated with improved Cx40 expression.

Ex vivo assessment of protective effects of carvacrol against DNA lesions induced in primary rat cells by visible light excited methylene blue (VL+MB).

Carvacrol belongs to frequently occurring phenolic components of essential oils (EOs) and it is present in many kinds of plants. Biological effect of this phenol derivative on human beings is however not sufficiently known. The present study was undertaken to evaluate the level of VL+MB-induced oxidative DNA lesions in hepatocytes and testicular cells (freshly isolated from control or carvacrol-watered rats) by the modified single cell gel electrophoresis (SCGE). The results showed that carvacrol significantly reduced the level of VL+MB-induced oxidized bases (EndoIII- and Fpg-sensitive sites) only in hepatocytes but not in testicular cells. Chromosomal aberration assay of primary hepatocytes, isolated from control or carvacrol-watered rats did not testify any genotoxic activity of carvacrol. We suggest that in vivo applied synthetic carvacrol, whose antioxidative activity was confirmed by DPPH assay, exhibits primarily a strong hepatoprotective activity against oxidative damage to DNA.

Omega-3 fatty acids and atorvastatin suppress ventricular fibrillation inducibility in hypertriglyceridemic rat hearts: implication of intracellular coupling protein, connexin-43.

Omega-3 fatty acids (omega-3 FA) and statins exhibit besides lipid-lowering effects the antiarrhythmic ability in clinic, while definite mechanisms are not yet elucidated. Our goal was to examine whether these compounds can modulate inducibility of hypertriglyceridemic (HTG) rat heart to ventricular fibrillation (VF) and myocardial cell-to-cell coupling protein connexin-43 (Cx43). HTG and healthy Wistar rats were orally treated with omega-3 FA(30 mg/100 g/day/2 mth) and atorvastatin (Ato, 0.5 mg/100 g/day/2 mth) and compared to untreated rats. Susceptibility of the heart to electrically-inducible VF and functional parameters were monitored using Langendorff-perfused isolated heart. Ventricular tissues from treated and untreated HTG and Wistar rat hearts were processed for ultrastructure examination as well as for analysis of myocardial Cx43 distribution and expression using antiCx43 MAB, immunofluorescence and immunoblotting. Both, omega-3 FA and atorvastatin reduced elevated blood pressure, triglycerides and heart rate in HTG rats. Compared to Wistar the threshold to induce VF was lower in HTG rat hearts, which exhibited abnormal Cx43 distribution, decreased immunostaining and elevated phosphorylated form of Cx43. In contrast, an enhancement of immunostaining of Cx43, suppression of hyperphosphorylation of Cx43 and improvement of cardiomyocyte and intercellular junction integrity by omega-3 FA and atorvastatin was associated with a significant increase of threshold for VF. Moreover, treatment resulted in up-regulation of myocardial Cx43 and increase of VF threshold in healthy rats that was associated with up-regulation of Cx43. Results indicate that antiarrhythmic effects of omega-3 FA and atorvastatin are linked with modulation of expression and/or phosphorylation of Cx43 and protection of cardiomyocyte and cell-to-cell junction integrity. As both compounds are ligands for PPAR, a possible regulation of Cx43 gene expression and pathways involved in Cx43 phosphorylation should be investigated.

Pycnogenol efficiency on glycaemia, motor nerve conduction velocity and markers of oxidative stress in mild type diabetes in rats.

The aim of this study was to describe the effects of Pycnogenol at various doses on preprandial and postprandial glucose levels, the levels of thiobarbituric acid reactive substances (TBARs) and N-acetyl-beta-d-glucosaminidase (NAGA) and on motor nerve conduction velocity (MNCV) in streptozotocin (STZ)-induced diabetic rats. Pycnogenol treatment (10, 20, 50 mg/kg body weight (b.w.)/day) lasted for 8 weeks after induction of diabetes. Pycnogenol significantly decreased elevated levels of preprandial glycaemia in treated animals at all doses. At doses of 10 mg/kg b.w./day and 20 mg/kg b.w./day it significantly decreased elevated levels of postprandial glycaemia compared with diabetic non-treated animals. Pycnogenol failed to induce a significant decrease of postprandial glycaemia at a dose of 50 mg/kg b.w./day. Pycnogenol improved significantly the impaired MNCV at doses of 10 and 20 mg/kg b.w./day compared with non-treated animals. The levels of TBARs were elevated in diabetic rats. The levels of NAGA increased gradually despite the treatment. Pycnogenol failed to affect the increased levels of TBARs and NAGA. Pycnogenollowered the elevated levels of glycaemia and reduced the decline in motor nerve conduction velocity in STZ-induced diabetic rats. The effect of Pycnogenol on postprandial glycaemic levels and MNCV was not dose-dependent.

Crowding-induced alterations in vascular system of Wistar-Kyoto rats: role of nitric oxide.

The aim of this study was to determine the effect of chronic crowding on the cardiovascular system of Wistar-Kyoto (WKY) rats. Rats were randomly divided into the control (480 cm(2) per rat) or crowded (200 cm(2) per rat) group for eight weeks. Body weight, blood pressure (BP), heart rate and plasma nitrate/nitrite levels of the crowded rats were not different from controls at the end of the experiment. Plasma corticosterone exhibited an increasing trend (5.7+/-1.8 vs. 12.6+/-3.7 ng/ml, p=0.08) while blood glucose was significantly reduced in the crowded rats in comparison with the controls. Nitric oxide (NO) synthase activity and nitrate/nitrite levels of the crowded rats were significantly elevated in the aorta by 80 % and 20 %, respectively, but unchanged in the left ventricle. Moreover, acetylcholine-induced relaxation was significantly increased in the crowded rats in both the femoral artery (61+/-5 % vs. 76+/-5 %, p<0.001) and mesenteric artery (51+/-6 % vs. 72+/-7 %, p<0.001). In conclusion, results suggest that chronic crowding may increase vasorelaxation and vascular NO production in normotensive rats. This may be considered as an adapting mechanism preventing the development of the stress-related elevation of BP. Additionally, results also suggest caution in the housing of rats because an inappropriate crowding may affect results of the experiment significantly.

Mesenteric ischemia/reperfusion-induced intestinal and vascular damage: effect of stobadine.

This study examined the effects of the pyridoindole compound stobadine on intestinal and vascular injury following mesenteric ischemia/reperfusion (I/R) in rats. Ischemia was induced by occlusion of the superior mesenteric artery (SMA) for 60 min, followed by 30 min reperfusion. To characterize gut impairment, some parameters of intestinal damage and biochemical variables, such as GSH content, activity of a lysosomal enzyme N-acetyl-beta-D-glucuronidase and activity of gamma-glutamyl transpeptidase, were determined. Vascular I/R-induced damage was evaluated as changes in acetylcholine evoked relaxation of mesenteric artery rings under isometric conditions. A method of amplified chemiluminescence (CL) was used to detect production of reactive oxygen species (ROS). Following I/R, pronounced intestinal injury of various intensities was observed, with maximal changes occurring in the terminal ileum. The effect of I/R was expressed mainly as increased vascular permeability, with protein leakage and subsequent hemorrhagic injury of the intestine as well as impaired endothelium-dependent SMA relaxation. Vessel dysfunction was manifested by a decrease of the maximal relaxation response to acetylcholine. An increase of CL, indicative of increased ROS production, was observed in both intestinal and vascular tissue. A novel antioxidant, stobadine, was found to reduce the increased vascular permeability and the extent of small intestine injury caused by I/R, to improve biochemical alterations accompanying I/R, to protect endothelial-dependent relaxation of mesenteric arteries, and to attenuate the CL response. The observed beneficial effect of stobadine indicates its possible application in the preventive and/or therapeutic approach to I/R-induced pathologies.

Changes in the function and ultrastructure of vessels in the rat model of multiple low dose streptozotocin-induced diabetes.

In this study we investigated functional changes in the femoral artery and ultrastructural alterations in mesenteric vessels and capillaries in the rat model of multiple low dose streptozotocin (STZ)-induced diabetes. Participation of oxidative stress in this model of diabetes was established by studying the effect of the pyridoindole antioxidant stobadine (STB) on diabetes-induced impairment. Experimental diabetes was induced by i.v. bolus of STZ (20 mg/kg) given for three consecutive days to male rats. At the 12(th) week following STZ administration, the animals revealed typical signs of diabetes, such as polyphagia, polydypsia and polyuria. There was no weight gain in the diabetic groups throughout the experiment. No exitus occurred in any group. Diabetes was characterised with high levels of plasma glucose, no significant changes in lipid metabolism, decreased serum levels of glutathione, increased serum levels of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAGA), injured endothelial relaxant capacity of the femoral artery and alterations in ultrastructure of mesenteric arteries and capillaries. Antioxidant STB in the dose of 25 mg/kg body weight i.p. (5 times per week) did not influence glucose levels, however, it mitigated biochemical, functional and ultrastructural changes induced by diabetes, suggesting a role of reactive oxygen species in diabetes-induced tissue damage.

Contribution to safe anti-inflammatory therapy with indomethacin.

Non-steroidal anti-inflammatory drugs possess not only therapeutic but also adverse effects, mainly on the gastrointestinal tract. The aim of this pilot study was to establish the ulcerogenic dose caused by daily administration of indomethacin to male Lewis rats. Further, the model of rat adjuvant arthritis (AA) was used to evaluate the protective effect of stobadine dipalmitate against indomethacin-induced gastroenteropathy. Indomethacin was administered subcutaneously in the daily dose of 5, 7, 10, 20 and 30 mg/kg b.w. Survival of the animals and damage of gastric and intestinal mucosa were monitored, and some biochemical parameters were determined. In AA rats stobadine dipalmitate was administered orally in the daily dose of 15 mg/kg. For the chronical experiments on AA rats the subcutaneous indomethacin dose of 5 mg/kg was selected as the therapeutic dose and the dose of 7 mg/kg was chosen as the adequate dose for gastropathy induction. The additive adverse effect of arthritis induction and indomethacin administration was demonstrated on the basis of gastric mucosa damage observations. The supposed stobadine gastro-protection was not confirmed.

Effect of melatonin on neurobehavioral dysfunctions induced by intrauterine hypoxia in rats.

Intrauterine hypoxia associated with oxidative stress represents an important risk factor for development of neurobehavioral dysfunctions. In the present study, we investigated the potential protective effect of melatonin (MEL) on neurobehavioral dysfunctions induced by chronic intrauterine hypoxia in rats by the anticonvulsant drug phenytoin (PHT), which is known by its teratogenic potential. Pregnant female rats (Wistar/DV) were orally treated by PHT (150 mg/kg) from day 7 to 18 of gestation. MEL was dissolved in drinking water (40 microg/ml) and administered from day 0 to 19 of gestation. Neurobehavioral development of offspring was evaluated from birth up to day 90 of postnatal life. The results of the study confirmed the high behavior-teratogenic potential of PHT. Prenatal administration of PHT resulted in delayed neuromotor and reflex development, decreased exploration in the open field, abnormal "circling" and impaired performaces in water maze. Co-administration of MEL failed to have any effect on neurobehavioral dysfunctions induced by PHT treatment. Even administration of MEL alone caused developmental alterations in offspring manifested by accelerated testes descent and delayed onset of negative geotaxia and startle reflex. The results suggest to pay increased attention to MEL concerning its exogenous use during pregnancy.

Effect of melatonin on biochemical variables induced by phenytoin in organs of mothers, foetuses and offsprings of rats.

The present pre- and postnatal study was carried out to investigate the effect of melatonin (MEL), a potent antioxidant, on biochemical variables in the in vivo model of intrauterine hypoxia in rats. Chronic hypoxia was induced pharmacologically by the administration of the anticonvulsant phenytoin (PHT) during pregnancy. Rats were orally treated by PHT (150 mg/kg) from day 7 to 18 of gestation. MEL in drinking water (40 microg/ml) was administered from day 0 to 19 of gestation. The activity of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAGA) and the level of glutathione (GSH) were used as markers of tissue damage. In the prenatal study PHT-induced toxic damage was associated with an increase in NAGA activity and decrease of GSH level in placenta and in maternal serum and heart. MEL partially inhibited the changes of NAGA activity given above. MEL was able to increase only the decreased level of GSH in maternal heart. PHT decreased the level of GSH and increased the activity of NAGA in foetal organs, the improvement occurred in the liver and lungs, but not in foetal brain. In the postnatal study a significant increase of liver GSH level was found in all (control, MEL, PHT, MEL+PHT) groups of 1-day-old pups, while the activity of NAGA remained unchanged. We did not observe any significant differences in NAGA activity in the lungs and heart of pups. MEL increased the GSH level in lungs and heart. We concluded that administration of MEL during pregnancy partially inhibited the biochemical changes induced by PHT.

Gut and vessel alterations induced by mesenteric ischaemia/reperfusion in rats.

A rat model of transient occlusion of the superior mesenteric artery was used to study the intestinal and vascular injury induced by ischaemia/ reperfusion (I/R). A pronounced intestinal injury was observed, ranging from hyperaemia to severe haemorrhagic necrosis and bleeding. The length of the damaged intestinal segments reached 58.6% of the small intestine with a decrease of the wet weight in the I/R group. Sham operation resulted in 100% survival, I/R decreased survival to 40% after 24 h. Following I/R a significant increase of vascular permeability was observed in the small intestine. Gamma-glutamyl transpeptidase activity decreased aborally in sham operated rats and I/R reduced it further in all parts of the small intestine. I/R resulted in damaged endothelium-dependent relaxation of mesenteric artery rings. This was manifested by decreased maximal responses of arterial preparations to acetylcholine as well as decreased pD2 values. The results confirmed and specified the presumed effect of I/R on the small intestine and on vascular functions.

Effect of melatonin and stobadine on maternal and embryofoetal toxicity in rats due to intrauterine hypoxia induced by phenytoin administration.

The aim of the present study was to test the hypothesis that the natural antioxidant melatonin (MEL) and the synthetic antioxidant stobadine (STO) could reduce the incidence of maternal and embryofoetal toxicity in rats due to intrauterine hypoxia. Chronic hypoxia was induced pharmacologically by the administration of the anticonvulsant phenytoin (PHT) during the entire period of pregnancy. PHT disturbed the normal course of pregnancy, affected reproductive parameters and increased the incidence of skeletal anomalies. MEL did not protect the PHT-induced development toxicity in rat. On the other hand, STO partially prevented PHT-induced reduction of foetal and placental weights. Administration of STO also decreased the frequency of pre- and post-implantation loss and resorptions in the PHT group. We concluded that pretreatment of pregnant rats with STO prevented to a certain extent reproductive and foetal development alterations caused by chronic intrauterine hypoxia.

Determination of selective biochemical variables in pregnant and lactating mice after stobadine administration.

The aim of this study was to investigate the effects of the oral administration of stobadine (STB), a neuro- and cardioprotective drug with high antioxidant properties, on selective biochemical variables in pregnant and lactating mice. STB was administered orally at a dose of 50 mg/kg from day 15 of gestation to day 21 of lactation. Creatinine and urea were determined in serum, while acidity, proteins, glucose, ketones, bilirubin, urobilinogen, blood and creatinine were determined in urine from females on days 0, 15 and 18 of gestation and on days 7, 14, 21, and 28 postpartum (pp). In the biochemical variables investigated, no significant differences in STB-treated animals compared with controls were recorded on any of the days studied. Histopathological examination of kidney tissue did not reveal any adverse effect of STB administration.

Involvement of L-arginine-nitric oxide system in the response of isolated trachea to reactive oxygen species.

The aim of this study was to investigate the effect of reactive oxygen species (ROS), generated by electrolysis of Krebs-Henseleit solution (GE-KHS), on isolated guinea pig trachea and to assess the possible involvement of nitric oxide (NO) in the observed effects. The isolated trachea was superfused in GE-KHS, generating H2O2 and hypochlorous acid (HOCl), both of which slowly increased in the organ bath and reached final stable concentrations of 42 and 63 microM, respectively, at the rate of 20 ml/min(-1), and 261 and 245 microM, respectively, at the rate of 5 ml/min(-1). ROS GE-KHS-induced relaxation of tracheal rings was preceded by a small transient contraction in 40% and 65% of experiments when tracheal rings were superfused at the rate of 20 ml/min(-1) and 5 ml/min(-1), respectively. Removal of tracheal epithelium abolished the relaxation of the trachea induced by ROS GE-KHS and unmasked or potentiated trachealis contraction. The ROS GE-KHS-induced changes in trachealis tension were accompanied by an increase in thiobarbituric acid reactive substances (TBARS) and a decrease in nonprotein (NP) thiols in the trachea. These changes were inhibited by treatment with the antioxidant N-acetylcysteine (100 microM). Pretreatment of tracheal rings with the inhibitor of NO synthase (NOS) N(omega)-nitro-L-arginine (L-NOARG; 100 microM) for 20 min prior to exposure to ROS GE-KHS decreased the ROS GE-KHS-induced relaxation. When L-NOARG (100 microM) was present in the superfusing solution, not only 20 min before but also during superfusion with ROS GE-KHS, the evoked trachealis relaxation was reduced in the first 15 min but was enhanced in the 30th min. This late enhancement of relaxation was accompanied by a 12-fold increase in nitric oxide metabolites (NO(x)). ROS GE-KHS-induced elevation of TBARS levels in the trachea was decreased to 63% by pretreatment with L-NOARG (100 microM). Elevation of TBARS levels induced by incubation of brain liposomes with a hydroxyl radical generating system was decreased to 90% by L-NOARG (10, 100 microM), while the antioxidant stobadine (100 microM) nearly completely inhibited the evoked lipid peroxidation. In comparison with Trolox, L-NOARG exerted a slight scavenging effect on the 1,1-diphenyl-2-picrylhydrazyl radical. The presence of L-arginine and D-arginine in the superfusion fluid for 15-20 min before and during exposure of the trachea to ROS GE-KHS inhibited trachealis relaxation. Results indicate that epithelium derived NO may participate in the response of guinea pig trachea to ROS GE-KHS. The presence of L-NOARG in the bathing fluid during superfusion with ROS GE-KHS gave rise to NO(x), with relaxing activity. L- and D-arginine induced an inhibition of the relaxatory response to ROS GE-KHS and partially prevented a ROS-induced decrease in NP thiols. The involvement of the small antioxidant effects of L-NOARG and L- and D-arginine in the above mentioned actions of L-NOARG and L-arginine requires additional investigation.

The pyridoindole antioxidant stobadine attenuates albuminuria, enzymuria, kidney lipid peroxidation and matrix collagen cross-linking in streptozotocin-induced diabetic rats.

The aim of the present study was to investigate the effect of dietary supplementation with the pyridoindole antioxidant stobadine on kidney status and function in streptozotocin-induced diabetic rats. Diabetic male Wistar rats were fed a standard diet for 32 weeks or a diet supplemented with stobadine (0.05% w/w). The diabetic state was characterized by significantly elevated plasma levels of glucose, HbA1c and urea, severe reduction of total body weight and relatively enlarged kidneys. Elevated levels of conjugated dienes were recorded in the diabetic kidney confirming the presence of oxidative stress in diabetic animals. All diabetic rats showed marked proteinuria and albuminuria along with elevated excretion of the enzyme N-acetyl-beta-D-glucosaminidase. Long-term treatment of diabetic animals with stobadine significantly reduced total proteinuria, albuminuria and enzymuria, yet left the overall physical and glycemic status unaffected. It reduced oxidative damage of kidney tissue as shown by decreased conjugated diene level, and decreased matrix collagen cross-linking, as indicated by decreased breaking time values of rat tail tendons. These beneficial effects of stobadine, supported also by histological findings, may be brought about by virtue of the combination of its antioxidant potential with other effects, e.g., the postulated cholesterol-lowering ability or its ability to alter vascular reactivity and reduce the vascular tone.

Dietary supplementation of the pyridoindole antioxidant stobadine reduces vascular impairment in streptozotocin-diabetic rats.

We studied the influence of hyperglycemia lasting 1, 4, 6 and 8 months on the reactivity and ultrastructure of the aorta in Wistar rats. Moreover, the effect of the pyridoindole antioxidant stobadine ((-)-cis-2,8-dimethyl-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b]indole) on the changes induced by the 8-month hyperglycemia were studied. Hyperglycemia was induced by streptozotocin (STZ, 55 mg/kg i.v.). In the functional study, responses to KCl, acetylcholine (ACh), noradrenaline (NA) and hydrogen peroxide were evaluated under isometric conditions. The first changes in aortic reactivity started after 1 month of hyperglycemia and were exhibited by significantly increased NA-induced contractions. Relaxant responses to acetylcholine were decreased, although not significantly. Prolongation of hyperglycemia to 4, 6 and 8 months did not cause any additional significant changes in responsiveness to NA. Decreased ACh-induced relaxation and increased contractile responses to H2O2 were observed in month 4. The functional responses were not substantially deteriorated by prolongation of hyperglycemia to 6 and 8 months. Ultrastructural examination of the diabetic aorta showed disturbances in normal tissue organization. An 8-month supplementation of stobadine in diabetic rats resulted in the protection of aortic function as well as its ultrastructure. These results suggest that abnormalities occurring in the aorta of diabetic rats might result from the damaging effects of oxygen free radicals.

Stobadine inhibits lysosomal enzyme release in vivo and in vitro.

This study investigated the ability of stobadine, an effective cardioprotective drug with antiarrhythmic, antihypoxic and oxygen free radical scavenging properties, to protect cells against cyclophosphamide-induced toxic and cytotoxic damage in vivo and in vitro. Cyclophosphamide-induced toxic damage in female ICR mice was accompanied by marked increase in the activity of lysosomal enzymes in the spleen and kidney. Administration of stobadine prior to cyclophosphamide inhibited these biochemical changes. The in vivo protective effect of stobadine was comparable with its in vitro effect established in HeLa cells.

Effect of stobadine on cardiac injury induced by ischemia and reperfusion.

The aim of this work was to evaluate the effect of the antioxidant stobadine on ischemia/reperfusion-induced injury of the isolated rat heart. Experiments were performed according to Langendorff. Ischemia was induced by stop-flow lasting 30 minutes and the duration of repefusion was 30 minutes. Reperfusion of the ischemic heart induced dysrhythmias, with the most severe ones occurring in the first minutes of reperfusion. A significant increase in coronary perfusion pressure was observed starting after 15 min of reperfusion. Stobadine (10(-6) M applied 3 minutes before onset of ischemia and during reperfusion) prevented the deleterious effects to develop fully. The protective effect of stobadine observed in our experiments seems to be a consequence of its antioxidant properties.