To determine whether a short-term change in dietary habits affects postprandial lipemia in men and women in the same way, postprandial triglyceridemia was measured in age- and BMI-matched young healthy men and women after two weeks on the self-selected low-fat low-cholesterol (LF) diet and after another two weeks on the self-selected high-fat high-cholesterol (HF) diet. After a standardized challenge meal (1.4 g fat/kg of body weight), men had higher postprandial triglyceridemia than women on the HF diet but no such difference was observed on the LF diet. The results of this preliminary study suggest that there may be important sex differences in the mechanisms regulating the postprandial lipemia response to different diets, women being able to adapt better to the HF diet with respect to postprandial lipemia., J. Kovář, R. Poledne., and Obsahuje bibliografii
In our previous study, healthy volunteers showed considerable short-term dynamics and patterns of the coherence of high time resolution between respiratory movements (RESP), heart rate fluctuations (HRF), and arterial blood pressure fluctuations (BPF). These are physiological indicators of autonomic short-term coordination mediated mainly by the brainstem which could be impaired in severe brain disorders. We hypothesized a direct or indirect impairment of these functions by these disorders and examined these patterns in 16 patients suffering from severe brain disorders. We calculated partial and ordinary coherence sequences and found almost the same patterns of coherence sequences as in healthy volunteers, but a distinctly reduced frequency of pattern incidence in patients (2.8*1.5/10 min/patient and 9.5*2.8/10 min/subject, P<0.05). Furthermore, there is a significantly smaller frequency of HRF-related patterns in patients with poor outcome, compared with those in patients with good outcome (1.8*0.8/10 min/patient and 4.5*2.7/10 min/patient, P<0.05). We conclude that severe brain disorders reduce physiological short-term dynamics of autonomic coordination patterns in the mean values of patients, but not in every patient., U. Zwiener, Ch. Schelenz, S. Bramer, D. Hoyer., and Obsahuje bibliografii
The possible linear short-term coordination between respiratory movements (RESP), heart rate fluctuations (HRF), and arterial blood pressure fluctuations (BPF) in conscious human beings has not yet been investigated because of the restricted time resolution of conventional time series analysis. At present, this short-term dynamics as an expression of relative coordination can be quantified by newly developed adaptive autoregressive modeling of time series using Kalman filtering. Thus, in 6 conscious healthy volunteers, RESP, HRF, and BPF were recorded during 10 min in the supine position, at rest and during paced breathing. A considerable part of calculated ordinary and partial coherence sequences of short-term resolution between RESP and HRF, RESP and BPF, and partially between HRF and BPF showed patterns varying in time that could be correlated to changes between gradual coordinations (coherence changing between 0.40 and 0.95). They were more seldom complete or absent. There were mostly opposite changes between partial coherence sequences RESP-HRF/BPF and RESP-BPF/HRF demonstrating competitive behavior between these coordinations. Paced breathing did not essentially affect any observed characteristics. Therefore, these coherence dynamics are not essentially dependent on voluntary breathing movements. We conclude that to a different extent these linear and changing couplings between RESP, HRF, and BPF in conscious human beings exhibit properties of short-term complete and more frequently gradual coordinations showing dynamics that can not be determined by conventional methods., U. Zwiener, C. Schelenz, S. Bramer, D. Hoyer., and Obsahuje bibliografii
Adiponectin belongs to the group of biologically active substances secreted by adipocytes and referred to as adipokines. Disturbances in its secretion an d/or action are thought to be involved in the pathogenesis of some metabolic diseases. However, regulation of adiponectin secretion is poorly elucidated. In the present study, short-term regulation of adiponectin secretion in primary rat adipocytes was investigated. Isolated rat adipocytes were incubated in Krebs-Ringer buffer containing 5 mM glucose and insulin alone or in the combination with epinephrine, dibutyryl-cAMP, adenosine A 1 receptor antagonist (DPCPX), palmitate, 2-bromopalmitate or inhibitor of mitochondrial electron transport (rotenone). Adipocyte exposure for 2 h to insulin (1-100 nM) significantly increased secretion of adiponectin compared with secretion observed without insulin. Furthermore, secretion of adipon ectin from adipocytes incubated with glucose and insulin was reduced by 1 and 2 μ M epinephrine, but not by 0.25 and 0.5 μ M epinephrine. Under similar conditions, 1 and 2 mM dibutyryl-cAMP substantially diminished secretion of adiponectin, whereas 0.5 mM dibutyryl-cAMP was ineffective. Secretion of adiponectin was found to be effectively decreased by DPCPX. Moreover, ad ipocyte exposure to rotenone also resulted in a substantial diminution of secretory response of adipocytes incubated for 2 h with glucose and insulin. It was also demonstrated that palmitate an d 2-bromopalmitate (0.06-0.5 mM) failed to affect secretion of leptin. The obtained results indicated that in short-term regulation of adiponectin secretion, insulin and epinephrine exert the opposite effects. These effects appeared as early as after 2 h of exposure. Moreover, deprivation of energy or blockade of adenosine action substantially decreased secretion of adiponectin., T. Szkudelski, L. Nogowski, K. Szkudelska., and Obsahuje bibliografii a bibliografické odkazy
Ischemic postconditioning and remote conditioning are potentially useful tools for protecting ischemic myocardium. This study tested the hypothesis that 2,3-dehydrosilybin (DHS), a flavonolignan component of Silybum marianum , could attenuate cardiomyocyte damage following hypoxia/ reoxygenation by decreasing the generation of reactive oxygen species (ROS). After 5-6 days of cell culture in normoxic conditions the rat neonatal cardiomyocytes were divided into four groups. Control group (9 h at normoxic conditions), hypoxia/ reoxygenation group (3 h at 1 % O2 , 94 % N2 and 5 % CO2 followed by 10 min of 10 μmol·l -1 DHS and 6 h of reoxygenation in normoxia) and postconditioning group (3 h of hypoxia, three cycles of 5 min reoxygenation and 5 min hypoxia followed by 6 h of normoxia). Cell viability assess ed by propidium iodide staining was decreased after DHS treatment consistent with increased levels of lactatedehydrogenase (LDH) after reoxygenation. LDH leakage was significantly reduced when cardiomyocytes in the H/Re group were exposed to DHS. DHS treatment reduced H2O2 production and also decreased the generation of ROS in the H/Re group as evidenced by a fluorescence indicator. DHS treatment reduces reoxygenation-induced injury in cardiomyocytes by attenuation of ROS generation, H2O2 and protein carbonyls levels. In addition, we found that both the postconditioning protocol and the DHS treatment are associated with restored ratio of phosphorylated/total protein kinase C epsilon, relative to the H/Re group. In conclusion, our data support the protective role of DH S in hypoxia/reperfusion injury and indicate that DHS may act as a postconditioning mimic., E. Gabrielová, V. Křen, M. Jabůrek, M. Modrianský., and Obsahuje bibliografii
Aerobic exercise showed beneficial influence on cardiovascular systems in aging, and mechanisms underlying vascular adaption remain unclear. Large-conductance Ca2+ -activated K+(BKCa) channels play critical role s in regulating cellular excitability and vascular tone. This study determin ed the effects of aerobic exercise on aging -associated functional changes in BK Ca channels in cerebrovascular myocytes, Male Wistar rats aged 20- 22 mo nths were randomly assigned to sedentary (O -SED), low training frequency (O-EXL), and high training frequency group (O -EXH). Young rats were used as control. Compared to young rats, w hole -cell BK Ca current was decreased, and amplitude of spontaneous transient outward currents were reduced. The open probability and Ca2+/voltage sensitivity of single BK Ca channel were declined in O -SED, accompanied with a reduction of tamoxifen-induced BK Ca activation; the mean open time of BK Ca channels was shortened whereas close time was prolonged. Aerobic exercise training markedly alleviated the aging-associated decline independent of training frequency. Exercise three times rather than five times weekly may be a time and cost-saving training volume required to offer bene ficial effects to offset the functional declines of BK Ca during aging., Na Li, Bailin Liu, Sharon Xiang, Lijun Shi., and Obsahuje bibliografii
Sirtuin 1 (SIRT1) is involved in important biological processes such as energy metabolism and regulatory functions of the cell cycle, apoptosis, and inflammation. Our previous studies have shown hepatoprotective effect of polyphenolic compound resveratrol, which is also an activator of SIRT1. Therefore, the aim of our present study was to clarify the role of SIRT1 in process of hepatoprotection in animal model of drug-induced liver damage. Male Wistar rats were used for both in vivo and in vitro studies. Hepatotoxicity was induced by single dose of acetaminophen (APAP). Some rats and hepatocytes were treated by resveratrol or synthetic selective activator of sirtuin 1 (CAY10591). The degree of hepatotoxicity, the activity and expression of the SIRT1 were determined by biochemical, histological and molecular-biological assessments of gained samples (plasma, liver tissue, culture media and hepatocytes). Resveratrol and CAY attenuated APAP-induced hepatotoxicity in vivo and in vitro. Moreover, both drugs enhanced APAPreduced SIRT1 activity. Our results show that modulation of the SIRT1 activity plays a role in hepatoprotection. Synthetic activators of SIRT1 would help in understanding the role of SIRT1 and are therefore a major boost towards the search for specific treatment of liver disease., L. Wojnarová, N. Kutinová Canová, H. Farghali, T. Kučera., and Obsahuje bibliografii
Fourier spectral analysis of fore arm skin laser Doppler flowmetry (LDF) signal was performed in fifteen hypercholesterolemic patients (HP), without clinically manifest arterial diseases, and in fifteen age-matched healthy control subjects (CS), in order to investigate skin blood flowmotion (SBF). The LDF frequency intervals studied were: 0.01-1.6 Hz total spectrum, as well as 0.01-0.02 Hz (endothelial), 0.02-0. 06 Hz (sympathetic), 0.06-0.2 Hz (myogenic), 0.2-0.6 Hz (respiratory) and 0.6-1.6 Hz (cardiac). Skin microvascular reactivity (MVR ) to acetylcholine (ACh) and to sodium nitroprusside (SNP) iontophoresis was also investigated. HP showed a lower post-ACh increase in power spectral density (PSD) of the 0.01-0.02 Hz SBF subinterval compared to CS (1.80±1.73 PU 2 /Hz vs 3.59±1.78 PU 2 /Hz, respectively; p<0.005), while they did not differ in MVR from CS. In eleven HP the 0.01-0.02 Hz SBF subinterval showed a higher post-ACh PSD increase near to the statistical significance after 10 weeks of rosuvastatin therapy (10 mg/day) compared to pretreatment test (3.04±2.95 PU 2 /Hz vs 1.91±1.94 PU 2 /Hz; p=0.07). The blunted post-ACh increase in PSD of the 0.01-0.02 Hz SBF subinterval in HP suggests a skin endothelial dysfunction in these patients. This SBF abnormality showed a tendency to improve after rosuvastatin therapy in eleven treated patients., M. Rossi ... [et al.]., and Obsahuje seznam literatury
We have investigated slow inactivation in a rat axonal K+ channel, the I channel. Using voltage steps to potentials between -70 mV and +80 mV, from a holding potential of -100 mV, we observed a marked slowing of inactivation at positive potentials: the time constant was 4.5±0.4 s at -40 mV (mean ± S.E.M.), increasing to 14.7±2.0 s at +40 mV. Slowed inactivation at positive potentials is not consistent with published descriptions of C-type inactivation, but can be explained by models in which inactivation is preferentially from closed states (which have been developed for Kv2.1 and some Ca2+ channels). We tested two predictions of preferential closed-state models: inactivation should be more rapid during a train of brief pulses than during a long pulse to the same potential, and the cumulative inactivation measured with paired pulses should be greater than the inactivation at the same time during a continuous pulse. The I channel does not behave according to these predictions, indicating that preferential closed-state inactivation does not explain the slowing of inactivation we observe at positive potentials. Inactivation of the I channel therefore differs both from C-type inactivation, as presently understood, and from the inactivation of Kv2.1., A. Babes, E. Lörinczi, V. Ristoiu, M.L. Flonta, G. Reid., and Obsahuje bibliografii