We reported previously that the nitric oxide synthesis inhibitor Nv-nitro-L-arginine methyl ester (L-NAME) decreases cardiac output. Several studies have shown that inhibition of nitric oxide synthesis decreases the heart rate. In the present study, we investigated the effect of a single bolus administration of L-NAME on blood pressure and heart rate monitored for one hour in anesthetized rats and the influence of vagotomy and b1-receptor blocker metoprolol on the L-NAME induced bradycardia. After L-NAME treatment, the blood pressure rose immediately after the injection of the drug (peak response in the third minute: +24 %, p<0.001) and fell to the control level in the 20th minute. The heart rate decreased immediately after L-NAME administration, the lowest value being reached in the 10th minute (-14 %, p<0.001). However, bradycardia was sustained even after the blood pressure had returned to the control level. Bilateral vagotomy failed to influence the negative chronotropic effect of L-NAME, but bradycardia was completely abolished by metoprolol pretreatment. We concluded that the bradycardia evoked by L-NAME is mainly due to the withdrawal of sympathetic tone upon the heart rate. However, the cause of sustained bradycardia after normalization of blood pressure cannot be elucidated., J. Vág, C. Hably, J. Bartha., and Obsahuje bibliografii
The nitric oxide/cGMP system has been shown to play a crucial role in the mechanism of learning and memory. The aim of the present study was to investigate whether the inhibition of NO synthase in brain regions leads to alterations of spontaneous behavior in rats. Male Wistar rats were treated with NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) at the dose of 40 mg/kg/day. After 4 weeks of L-NAME treatment, NO synthase activity was significantly decreased by 75 % in the cerebellum, by 71 % in the cerebral cortex and by 72 % in the thoracic spinal cord. Decreased NO synthase activity in the nervous tissue was associated with decreased motor horizontal and vertical activities as well as by lowered frequency of sniffing, cleaning and defecation. It is concluded that the inhibition of NO synthase activity has a suppressive effect on spontaneous behavior of rats., L. Halčák, O. Pecháňová, Z. Žigová, L. Klemová, M. Novacký, I. Bernátová., and Obsahuje bibliografii
Carnosine (CARN) is an anti-glycating agent able to quench superoxide, and to neutralize 4-hydroxynonenal. Trolox-carnosine (CARN-T) was synthesized because of its resistance against degradation and to improve CARN antioxidant capacity. We evaluated the impact of trolox (TRO), CARN and its derivative CARN-T on oxidative stress (OS) in brain during rat adjuvant arthritis (AA). The experiments were done on healthy, control arthritic and arthritic animals with administration of CARN 150 mg/kg b.w., TRO 41 mg/kg b.w. and CARN-T 75 mg/kg b.w. in a daily dose during 28 days. Antioxidants did not affect the body weight on day 14, but on day 28 TRO enhanced the weight reduction. On day 14 and 28 CARN-T and TRO reduced arthritic score. IL-1beta, MCP-1 and MMP-9 were measured in plasma on day 14. MCP-1 was decreased by CARN-T and TRO. All antioxidants reduced IL-1beta and MMP-9 levels. Malondialdehyde, 4-hydroxynonenal and protein carbonyls were increased in brain. CARN, CARN-T and TRO prevented higher lipid and protein oxidation in brain. CARN and CARN-T caused no weight reduction like TRO that has an advantage in inflammatory arthritis. Moreover the antioxidants administered had a similar therapeutic effects on arthritic score, markers of inflammation in plasma and OS in brain., S. Poništ, L. Slovák, V. Kuncírová, T. Fedorova, A. Logvinenko, O. Muzychuk, D. Mihalová, K. Bauerová., and Obsahuje bibliografii
Mitochondria as an energy generating cell device are very sensitive to oxidative damage. Our previous findings obtained in hepatocytes demonstrated that Complex I of the respiratory chain is more sensitive to oxidative damage than other respiratory chain complexes. We present additional data on isolated mitochondria showing that palmityl carnitine oxidation is strongly depressed at a low (200 μM) tert-butyl hydroperoxide (tBHP) concentration, while oxidation of the flavoprotein-dependent substrate - succinate is not affected and neither is ATP synthesis inhibited by tBHP. In the presence of tBHP, the respiratory control index for palmityl carnitine oxidation is strongly depressed, but when succinate is oxidized the respiratory control index remains unaffected. Our findings thus indicate that flavoprotein-dependent substrates could be an important nutritional factor for the regeneration process in the necrotic liver damaged by oxidative stress., Z. Červinková, H. Rauchová, P. Křiváková, Z. Drahota., and Obsahuje bibliografii a bibliografické odkazy
The detailed mechanisms determining the course of congestive heart failure (CHF) and associated renal dysfunction remain unclear. In a volume overload model of CHF induced by creation of aorto- caval fistula (ACF) in Hannover Sprague -Dawley (HanSD) rats we explored the putative pathogenetic contribution of epoxyeicosatrienoic acids (EETs), active products of CYP -450 dependent epoxygenase pathway of arachidonic acid metabolism, and compared it with the role of the renin-angiotensin system (RAS). Chronic treatment with cis -4-[4-(3-adamantan -1-yl- ureido) cyclohexyloxy]benzoic acid (c-AUCB, 3 mg /l in drinking water), an inhibitor of soluble epoxide hydrolase (sEH) which normally degrades EETs, increased intrarenal and m yocardial EETs to levels observed in sham -operated HanSD rats, but did not improve the survival or renal function impairment. In contrast, chronic angiotensin -converting enzyme inhibition (ACEi, trandolapril, 6 mg /l in drinking water) increased renal blood flow, fractional sodium excretion and markedly improved survival, without affecting left ventricular structure and performance. Hence, renal dysfunction rather than cardiac remodeling determines long-term mortality in advanced stage of CHF due to volume o verload. Strong protective actions of ACEi were associated with suppression of the vasoconstrictor/sodium retaining axis and activation of vasodilatory/natriuretic axis of the renin -angiotensin system in the circulating blood and kidney tissue., L. Červenka, V. Melenovský, Z. Husková, A. Sporková, M. Bürgelová, P. Škaroupková, S. H. Hwang, B. D. Hammock, J. D. Imig, J. Sadowski., and Obsahuje bibliografii
We analyzed the effect of FK 506 on the production of nitric oxide by macrophages. Isolated rat peritoneal macrophages were cultured for 24 h with or without lipopolysaccharide (LPS) (5 µg/ml) and in the absence or presence of FK 506 (0.1 and 1 µg/ml). The concentration of NO2- in culture supernatants was taken as a measure of nitric oxide production. FK 506 (0.1 and 1 µg/ml) reduced the LPS-induced increase of NO2- levels by 68 % and 81 %, respectively. The impact of cyclosporin A (CsA) was studied in order to compare their effects. CsA (0.1 and 1 µg/ml) decreased the levels of nitrites by 39 % and 69 %, respectively. The results obtained suggest that both immunosuppressive drugs exhibit a dose-dependent inhibitory effect on nitric oxide production and that FK 506 is a more potent agent than CsA in this respect., P. Střeštíková, B. Otová, M. Filipec, H. Farghali., and Obsahuje bibliografii
Metformin is widely used in the treatment of Type 2 diabetes, however, mechanisms of its antihyperglycemic effect were not yet fully elucidated. Complex I of mitochondrial respiration chain is considered as one of the possible targets of metformin action. In this paper, we present data indicating that the inhibitory effect of metformin can be tested also in liver homogenate. Contrary to previous findings on hepatocytes or mitochondria under our experimental conditions, lower metformin concentrations and shorter time of preincubation give significant inhibitory effects. These conditions enable to study the mechanism of the inhibitory effect of metformin in small samples of biological material (50-100 mg wet weight) and compare more experimental groups of animals because isolation of mitochonria is unnecessary., E. Páleníčková ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Using high-resolution oxygraphy, we tested the changes of various parameters characterizing the mitochondrial energy provision system that were induced by peroxidative damage. In the presence of succinate as respiratory substrate, 3 mM t-butyl hydroperoxide increased respiration in the absence of ADP, which indicated partial uncoupling of oxidative phosphorylation. Low activity of coupled respiration was still maintained as indicated by the ADP-activated and oligomycin-inhibited respiration. However, during the incubation the phosphorylative capacity decreased as indicated by the continuous decrease of the mitochondrial membrane potential. Under these experimental conditions the maximum capacity of the succinate oxidase system was inhibited by 50 % in comparison with values obtained in the absence of t-butyl hydroperoxide. Our data thus indicate that the oxygraphic evaluation of mitochondrial function represents a useful tool for evaluation of changes participating in peroxidative damage of cell energy metabolism., P. Křiváková, A. Lábajová, Z. Červinková, Z. Drahota., and Obsahuje bibliografii a bibliografické odkazy
In contrast to the well-established anti-apoptotic effect of Bcl-2 protein, we have recently demonstrated that Bcl-2 overexpression by vaccinia virus causes apoptosis in BSC-40 cells, while it prevents apoptosis in HeLa G cells. Given the key role of mitochondria in the process of apoptosis, we focused on effects of Bcl-2 expression on mitochondrial energetics of these two cell lines. In this study we present data indicating that BSC-40 cells derive their ATP mainly from oxidative phosphorylation whereas HeLa G cells from glycolysis. More importantly, we show that in both cell lines, Bcl-2 inhibits mitochondrial respiration and causes a decrease of the ATP/ADP ratio. However, it appears that BSC-40 cells cannot sustain this decrease and die, while HeLa G cells survive, being adapted to the low ratio of ATP/ADP maintained by glycolysis. Based on this observation, we propose that the outcome of Bcl-2 expression is determined by the type of cellular ATP synthesis, namely that Bcl-2 causes apoptosis in cells relying on oxidative phosphorylation., M. Vrbacký, J. Krijt, Z. Drahota, Z. Mělková., and Obsahuje bibliografii