The effect of cytokinins benzylaminopurine (BAP) and thidiazuron on photosynthetic rate and enzyme activities in sugar beet, pea, meadow fescue and reed fescue leaves was studied. Low concentrations (3-10 g nr3) stimulated the net photosynthetic rate, the activities of ribulose-l,5-bisphosphate carboxylase/oxygenase (RuBPCO) and other enzymes of the carboxylation phase of Calvin cycle, i.e. ribose phosphate isomerase and phosphoribulokinase, and the cycle including the NADP-glyceraldehyde phosphate dehydrogenase complex. On the contrary, there was no change in phosphoenolpyruvate carboxylase activity. In treated leaves the quantity of RuBPC increased along with increases in the level of total leaf proteins. Thus cytokinins act, probably, by specific altering of the synthesis of certain proteins. Inducing or stimulating the synthesis of essential proteins involved in photosynthetic processes, cytokinins cause changes in photosynthetic activity.
The role of brain derived nitric oxide in the physiology and behavior remains disputable. One of the reasons of the controversies might be systemic side effects of nitric oxide synthase inhibitors. Therefore, under nNOS inhibition by 7- nitroindazole (7-NI) we carried out recordings of blood gasses, blood pressure and spontaneous EEG in conscious adult rats. Locomotion and spontaneous behavior were assessed in an open field. In addition skilled walking and limb coordination were evaluated using a ladder rung walking test. The blood gas analysis revealed a significant increase in pCO2 180 min and 240 min after the application of 7-NI. The power and entropy decreased simultaneously with a shift of the mean frequency of the spontaneous EEG toward slow oscillations after 7-NI treatment. The thresholds of evoked potentials underwent a significant drop and a trend towards a slight increase in the I-O curve slope was observed. 7-NI significantly suppressed open field behavior expressed as distance moved, exploratory rearing and grooming. As for the ladder rung walking test the 7-NI treated animals had more errors in foot placement indicating impairment in limb coordination. Therefore our findings suggest that 7-NI increased cortical excitability and altered some physiological and behavioral parameters., C. Boržíčková, A. Mikulecká, J. Otáhal., and Obsahuje bibliografii
The effect of abscisic acid (ABA) on the net photosynthetic rate the ribulose 1,5-bisphosphate carboxylase (RuBPC) and the phosphoenolpyruvate caiboxylase (PEPC) activities, the chlorophyll (Chl) content and growth of pea plants (Pisum sativum L.) grown under "white" (WR) or blue radiation (BR), were investigated. BR as compared to WR enhanced P^, the activities of examined enzymes, and Chl content. In špite of higher of the plants grown under BR, diy matter of their shoots was lower in comparison with WR. ABA-treated plants grown under both WR and BR showed reduction in Pn- ABA had no effect on the activities of both RuBPC and PEPC and the Chl content. Independent on the radiation quality, ABA reduced stem elongation, but did not affect the biomass of whole shoots.
We investigated the effects of in vivo treatment with the angiotensin-converting enzyme inhibitor (ACE-I) captopril and/or of in vitro administration of L-arginine on the metabolism and ischemia-reperfusion injury of the isolated perfused rat myocardium. Captopril (50 mg/l in drinking water, 4 weeks) raised the myocardial content of glycogen. After 25-min global ischemia, captopril treatment, compared with the controls, resulted in lower rates of lactate dehydrogenase release during reperfusion (8.58±1.12 vs. 13.39±1.88 U/heart/30 min, p<0.05), lower myocardial lactate contents (11.34±0.93 vs. 21.22±4.28 µmol/g d.w., p<0.05) and higher coronary flow recovery (by 25 %), and prevented the decrease of NO release into the perfusate during reperfusion. In control hearts L-arginine added to the perfusate (1 mmol/l) 10 min before ischemia had no effect on the parameters evaluated under our experimental conditions, presumably because of sufficient saturation of the myocardium with L-arginine. In the hearts of captopril-treated rats, L-arginine further increased NO production during reperfusion and the cGMP content before ischemia. Our results have shown that long-term captopril treatment increases the energy potential and has a beneficial effect on tolerance of the isolated heart to ischemia. L-arginine added into the perfusate potentiates the effect of captopril on the NO signaling pathway., J. Divišová, H. Vavřínková, M. Tutterová, L. Kazdová, E. Meschišvili., and Obsahuje bibliografii
Statins are powerful lipid-lowering drugs, widely used in patients with hyperlipidemia and coronary artery disease. It was found, however, that statins appear to have a pleiotropic effect beyond their lipid-lowering ability. They exert anti-inflammatory, antithrombotic and antioxidant effects, increase nitric oxide production and improve endothelial dysfunction. The aim of our study was to examine the effect of chronic and acute treatment with simvastatin on the contractile function of the isolated perfused rat heart after ischemia/reperfusion injury. Contractile function was measured on isolated rat hearts, perfused according to Langendorff under constant pressure. The hearts were subjected to 20 min of global ischemia, followed by 40 min of reperfusion. To investigate the acute effect, simvastatin at a concentration of 10 μmol/l was added to the perfusion solution during reperfusion. In chronic experiments the rats were fed simvastatin at a concentration of 10 mg/kg for two weeks before the measurement of the contractile function. Acute simvastatin administration significantly increased reparation of the peak of pressure development [(+dP/dt)max] (52.9±8.2 %) after global ischemia, as compared with the control group (28.8±5.2 %). Similar differences were also observed in the time course of the recovery of [(+dP/dt)max]. Chronic simvastatin was without any protective effect. Our results reveal that the acute administration of simvastatin during reperfusion, unlike the chronic treatment, significantly reduced contractile dysfunction induced by ischemia/reperfusion injury. This supports the idea of possible cardioprotective effect of statin administration in the first-line therapy of the acute coronary syndrome., O. Szárszoi, J. Malý, P. Ošťádal, I. Netuka, J. Bešík, F. Kolář, B. Ošťádal., and Obsahuje bibliografii a bibliografické odkazy
To determine whether acutely-induced supraphysiological hyperinsulinemia influences brain metabolism in patients with type 1 diabetes (D) and healthy controls (C) as detected by MR Spectroscopy. Group D consisted of 4 patients with the average duration of diabetes for 7 years. They were matched according to age, sex and BMI to 4 healthy controls. 1H MR Spectroscopy was performed with a 1.5 Tesla. Spectra were obtained from parietooccipital white matter repeatedly during a 3-h hyperinsulinemic euglycemic clamp with 2 mU.kg-1.min-1. In group D, significantly lower basal concentrations of N-acetylaspartate (p=0.02), choline (p=0.03), creatine (p=0.002) and inositol (p=0.007) were detected compared to C. After the induction of hyperinsulinemia, concentrations of choline, creatine, GABA, inositol, lactate, NAA and composite signal glutamate + glutamine (Glx) stayed stable. The detection of glucose signal is less realiable at 1.5 Tesla but we registered the alteration in glucose concentration (p=0.003) in the whole group. Originally sightly elevated glucose concentration in D decreased on the contrary to the increase of originally lower glucose level in C. In conclusions, brain metabolism was altered in D. Short term supraphysiological euglycemic hyperinsulinemia induced changes in the concentration of brain glucose in both C and D., S. Kratochvílová, A. Škoch, M. Dezortová, E. Švehlíková, M. Hill, J. Brunová, M. Hájek, T. Pelikánová., and Obsahuje bibliografii
The novel myokine irisin has been reported as a therapeutic target for metabolic disease. The objective of this study is to reveal the effects of aerobic training (AT) and resistance training (RT) on circulating irisin levels and their associations with change of body composition in overweight/obese adults. Twenty eight overweight/obese adults (BMI>23 kg/m2) were included in this study and compared before and after 8 weeks of exercise program (60 min/day, 5 times in a week). The subjects, in both aerobic and resistance training, showed significant improvement in anthropometric parameters and exercise capacities including maximal oxygen uptake and muscle strength. Interestingly, the circulating irisin was significantly increased in resistance training group (p=0.002) but not in aerobic training (p=0.426) compared to control group. In addition, we found the positive correlation between change of the circulating irisin and muscle mass (r=0.432, p=0.022) and the negative correlation between change of the circulating irisin and fat mass (r=-0.407, p=0.031). In the present pilot study, we found that circulating irisin level was increased by 8 weeks of resistance training in overweight/obese adults, suggesting that resistance training could be the efficient exercise type in overweight/obese considering positive change of body composition concomitant with increase of irisin levels., Hee-Jae Kim, Hyo-Joo Lee, Byunghun So, Jun Seok Son, Donghyun Yoon, Wook Song., and Obsahuje bibliografii
Agroclavine is a natural, clavine type of ergot alkaloid with D1 dopamine and ?-adrenoceptor agonistic properties. We showed previously that in vitro agroclavine enhances natural killer (NK) cell activity, increases interleukin-2 and interferon-gamma production and prolongs the survival time of tumor-bearing mice. The aim of this study was 1) to test the effect of agroclavine on NK activity in vivo, and 2) to assess the potential toxicity of high doses of agroclavine on cardiac and liver functions using creatine kinase MB (CKMB) and alanine aminotransferase (ALT) as biochemical markers in normal and stressed animals. The effect of stress was studied because we examined promising anticancer properties of agroclavine and malignant diseases are supposed to be a potent stressful event for patients. In our experiments 3-month-old male rats of the Wistar-Kyoto strain were used. Agroclavine was injected intraperitoneally (0.5 mg/kg or 0.05 mg/kg) 30 min before stress (four hours' restraint and immersion in 23 °C water). The animals were killed 30 min after stress, blood was collected and the spleen was removed. Non-stressed animals treated with agroclavine were killed 5 h after the drug administration. The results confirmed our previous in vitro results and showed that also in vivo agroclavine increases NK cell activity under non-stress conditions. Agroclavine only slightly increased CKMB and had no influence on ALT in non-stressed animals. These promising results are limited by the fact that agroclavine (0.5 mg/kg) diminished NK cell activity and significantly increased ALT and CKMB under stress conditions., M. Starec, A. Fišerová, J. Rosina, J. Málek, M. Kršiak., and Obsahuje bibliografii
We conducted a hydroponic experiment in order to study effects of the ammonium/nitrate ratio (0:15, 5:10, 7.5:7.5, and 10:5) on photosynthetic characteristics and biomass accumulation in Brassica chinensis under low light intensity and water stress. Results showed that net photosynthetic rate, transpiration rate, intrinsic water-use efficiency, stomatal conductance, intercellular CO2 concentration, effective quantum yield of PSII photochemistry, electron transport rate, and nonphotochemical quenching were lower in the treatment (low light intensity and water deficit) than those in the control, whereas stomatal limitation increased. Minimum fluorescence, maximal quantum yield of PSII photochemistry, and photochemical quenching were largely unchanged. Pigment contents first increased and then decreased as the ammonium/nitrate ratios were altered, with significant differences between treatment and control observed at all ratios except for 10:5. Biomass first increased slightly and then decreased both in treated and control plants. Results suggest that economic losses caused by extreme conditions can be minimized by a proper adjustment of the ammonium/nitrate ratio., H. Q. Shang, G. M. Shen., and Obsahuje bibliografii
The effect of increased coronary flow on transmural ventricular repolarization was investigated in six pentobabital-anesthetized sheep. Fresh blood at 10 ml/min was injected into the left circumflex coronary artery (LCX) in addition to the normal coronary flow. Unipolar electrocardiograms were simultaneously registered from epicardium, mid-myocardium and endocardium with fine plunge needles. Activation-recovery interval (ARI) was measured from the unipolar electrocardiograms and was used for estimating the ventricular repolarization duration. It was found that intracoronary blood injection (n=3) prolonged ARI in the epicardium, mid-myocardium and endocardium by an average of 34 ± 16, 28 ± 18 and 25 ± 13 ms, respectively (p<0.01). Pretreatment with nitro-L-arginine (n=3), a nitric synthase inhibitor, diminished the flow-induced ARI prolongation across the ventricular wall. In conclusion, an increase in coronary flow lengthens the duration of transmural ventricular repolarization. These effects appear to be mediated by nitric oxide from the coronary endothelium., Y.-Z. Zhang, B. He, L.-X. Wang., and Obsahuje bibliografii a bibliografické odkazy