Although male rats generally outperform females in many spatial tasks, sometimes gender differences are not present. This preliminary study examined gender effects in the Enemy avoidance task, in which a rat on a stable circular arena avoids approaching a small mobile robot while collecting randomly dispersed small pellets. Whenever distance between robot and the rat dropped below 25 cm, animal was punished by a mild footshock. Female rats showed thigmotaxis, hypolocomotion and avoidance of robot in the habituation phase, when approaches were not punished. No statistically significant differences in avoidance learning under reinforcement training sessions were observed; but females still spent significantly more time at periphery of the arena and foraged less than males. We conclude that females were able to perform at the same level as males under reinforcement despite different behavioral strategy. The thigmotaxic behavior appears to function as innate escape strategy in female rats triggered by the stressing effect of the moving robot rather then the presence of shocks., J. Svoboda, ... [et al.]., and Obsahuje seznam literatury
We studied the expression of myosin heavy chain isoforms at mRNA and protein levels as well as fiber type composition in the fast extensor digitorum longus (EDL) and slow soleus (SOL) twitch muscles of adult inbred Lewis strain rats. Comparison of the results from Real Time RT-PCR, SDS-PAGE and fiber type analysis showed corresponding proportions of MyHC transcripts (MyHC-1, -2a, -2x/d, -2b), protein isoforms (MyHC-1, -2a, -2x/d, -2b) and fiber types (type 1, 2A, 2X/D, 2B) in both muscles. Furthermore, we found that slow MyHC-1 mRNA expression in the SOL was up to three orders higher than that of fast MyHC transcripts. This finding can explain the predominance of MyHC-1 isoform and fiber type 1 and the absence of pure 2X/D and 2B fibers in the SOL muscle. Based on our data presenting quantitative evidence of corresponding proportions between mRNA level, protein content and fiber type composition, we suggest that the Real Time RT-PCR technique can be used as a routine method for analysis of muscle composition changes and could be advantageous for the analysis of scant biological samples such as muscle biopsies in humans., J. Žurmanová, T. Soukup., and Obsahuje seznam literatury
We developed a new method for the quantitative determination of myosin heavy chain (MyHC) isoforms taking advantage of immunochemical differences and based on the ELISA principle. In the present paper we compare anal ysis of MyHC isoforms using the SDS-PAGE and the ELISA methods in the same samples of adult female inbred Lewis strain euthyroid, hyperthyroid and hypothyroid rats. In all thyroid states, the same composition and corresponding changes of MyHC isoforms were determined using both methodological approaches in the slow soleus and the fast extensor digitorum longus muscles. Our results showed that ELISA can be used for a “semi-quantitative” or “comparative” measurement of MyHC isoforms in multiple muscle samples, but that it is neither more exact no r faster compared to SDS-PAGE., Jan Říčný., and Obsahuje bibliografii a bibliografické odkazy
The aim of the present study was to compare the oscillations of oxygenation in skeletal muscle between early and late phases in prolonged exercise. During prolonged exercise at 60 % of peak oxygen uptake ( o2) for 60 min and at rest, oxygenated hemoglobin/myoglobin (Hb/MbO2) and total Hb/Mb (THb/Mb) were determined by near-infrared spectroscopy in the vastus lateralis. Power spectra density (PSD) for the difference between Hb/MbO2 and THb/Mb (−HHb/MbO2: deoxygenation) was obtained by fast Fourier transform at rest, in the early phase (1-6 min) and in the late phase (55-60 min) in exercise. Peak PSD in the early phase was significantly higher than that at rest. There were at least three peaks of PSD in exercise. The highest peak was a band around 0.01 Hz, the next peak was a band around 0.04 Hz, and the lowest peak was a band around 0.06 Hz. PSD in the early phase was not significantly different from that in the late phase in exercise. Heart rate (HR) showed a continuous significant increase from 3 min in exercise until the end of exercise. Skin blood flow (SBF) around the early phase was significantly lower than that around the late phase. It was concluded that oscillation of oxygenation in the muscle oxygen system in the early phase is not different from that in the late phase in prolonged exercise despite cardiovascular drift., T. Yano, ... [et al.]., and Obsahuje seznam literatury
The purpose of the present study was to examine whether the level of oxygen uptake (V.o2) at the onset of decrement-load exercise (DLE) is lower than that at the onset of constant-load exercise (CLE), since power output, which is the target of V.o2 response, is decreased in DLE. CLE and DLE were performed under the conditions of moderate and heavy exercise intensities. Before and after these main exercises, previous exercise and post exercise were performed at 20 watts. DEL was started at the same power output as that for CLE and power output was decreased at a rate of 15 watts per min. V.o2 in moderate CLE increased at a fast rate and showed a steady state, while V.o2 in moderate DLE increased and decreased linearly. V.o2 at the increasing phase in DLE was at the same level as that in moderate CLE. V.o2 immediately after moderate DLE was higher than that in the previous exercise by 98±77.5 ml/min. V.o2 in heavy CLE increased rapidly at first and then slowly increased, while V.o2 in heavy DLE increased rapidly, showing a temporal convexity change, and decreased linearly. V.o2 at the increasing phase of heavy DLE was the same level as that in heavy CLE. V.o2 immediately after heavy DLE was significantly higher than that in the previous exercise by 156±131.8 ml/min. Thus, despite the different modes of exercise, V.o2 at the increasing phase in DLE was at the same level as that in CLE due to the effect of the oxygen debt expressed by the higher level of V.o2 at the end of DLE than that in the previous exercise., T. Yano, H. Ogata, R. Matsuura, T. Arimitsu, T. Yunoki., and Obsahuje bibliografii a bibliografické odkazy
Hereditary hypertriglyceridemic (hHTG) rats are characterized by increased blood pressure and impaired endotheliumdependent relaxation of conduit arteries. The aim of this study was to investigate the effect of long-term (4 weeks) treatment of hHTG rats with three drugs which, according to their mechanism of action, may be able to modify the endothelial function: simvastatin (an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase), spironolactone (an antagonist of aldosterone receptors) and L-arginine (a precursor of nitric oxide formation). At the end of 4th week the systolic blood pressure in the control hHTG group was 148±2 mm Hg and in control normotensive Wistar group 117±3 mm Hg. L-arginine failed to reduce blood pressure, but simvastatin (118±1 mm Hg) and spironolactone (124±4 mm Hg) treatment significantly decreased the systolic blood pressure. In isolated phenylephrine-precontracted aortic rings from hHTG rats endothelium-dependent relaxation was diminished as compared to control Wistar rats. Of the three drugs used, only simvastatin improved acetylcholine-induced relaxation of the aorta. We conclude that both simvastatin and spironolactone reduced blood pressure but only simvastatin significantly improved endothelial dysfunction of aorta. Prominent increase in the expression of eNOS in large conduit arteries may be the pathophysiological mechanism underlying the protective effect of simvastatin in hHTG rats., J. Török, I. L'upták, J. Matúšková, O. Pecháňová, J. Zicha, J. Kuneš, F. Šimko., and Obsahuje bibliografii
Inhalational anesthetics have demonstrated cardioprotective effects against myocardial ischemia-reperfusion injury. Clinical studies in cardiac surgery have supported these findings, although not with the consistency demonstrated in experimental studies. Recent investigations have questioned the advantages of inhalational over intravenous anesthetics with respect to cardiac protection. Ketamine has been shown to be comparable with sufentanil, and has even demonstrated anti-inflammatory properties. Dexmedetomidine has been established as a sedative/anesthetic drug with analgesic properties, and has also demonstrated myocardial protective effects. In this retrospective observational study, the influence of ketamine-dexmedetomidinebased anesthesia (KET-DEX group; n=17) on the release of cardiac biomarkers was compared with that of sevofluranesufentanil-based anesthesia (SEVO group; n=21) in patients undergoing elective coronary artery bypass grafting. Compared with the SEVO group, the KET-DEX group exhibited significantly reduced cardiac troponin I (2.22±1.73 vs. 3.63±2.37 µg/l; P=0.02) and myocardial fraction of creatine kinase (CK-MB) levels (12.4±10.4 vs. 20.3±11.2 µg/l; P=0.01) on the morning of the first postoperative day. Furthermore, cardiac troponin I release, evaluated as the area under the curve, was significantly reduced in the KET-DEX group (32.1±20.1 vs. 50.6±23.2; P=0.01). These results demonstrate the cardioprotective effects of ketamine-dexmedetomidine anesthesia compared with those of sevoflurane-sufentanil anesthesia., H. Říha ... [et al.]., and Obsahuje seznam literatury
The relative length of telomeres measured in peripheral blood leukocytes is a commonly used system marker for biological aging and can also be used as a biomarker of cardiovascular aging. However, to what extent the telomere length in peripheral leukocytes reflects telomere length in different organ tissues is still unclear. Therefore, we have measured relative telomere length (rTL) in twelve different human tissues (peripheral blood leukocytes, liver, kidney, heart, spleen, brain, skin, triceps, tongue mucosa, intercostal skeletal muscle, subcutaneous fat, and abdominal fat) from twelve cadavers (age range of 29 week of gestation to 88 years old). The highest rTL variability was observed in peripheral leukocytes, and the lowest variability was found in brain. We found a significant linear correlation between leukocyte rTL and both intercostal muscle (R=0.68, P<0.02) and liver rTL (R=0.60, P<0.05) only. High rTL variability was observed between different organs from one individual. Furthermore, we have shown that even slight DNA degradation (modeled by sonication of genomic DNA) leads to false rTL shortening. We conclude that the rTL in peripheral leukocytes is not strongly correlated with the rTL in different organs., D. Dlouha, J. Maluskova, I. Kralova Lesna, V. Lanska, J. A. Hubacek., and Obsahuje bibliografii
The objective of this study was to evaluate the influence of low-dose combined oral contraception (COC) on basal and stimulated (1 μg ACTH test) levels of serum and salivary cortisol (F), cortisone and on basal serum cortisol binding globulin (CBG), adrenocorticotropic hormone (ACTH), dehydroepiadrosterone (DHEA) and calculated free cortisol in healthy young women. Three-month administration of COC resulted in 1) significant increase of basal (454.0±125.0 to 860.9±179.7 nmol/l) and ACTH-stimulated serum cortisol in 30th min (652.3±60.5 to 1374.1±240.6 nmol/l); 2) no significant change of basal (15.4±7.3 to 18.9±8.5 nmol/l) and ACTH-stimulated salivary cortisol at the 30th min (32.4±8.8 to 32.9±9.0 nmol/l); 3) no significant change of basal serum cortisone (38,8±7.68 to 45.2±24.2 nmol/l) and ACTH-stimulated cortisone at the 30th (34.8±10.9 to 47.0±35.7 nmol/l); 4) significant increase of basal ACTH (17.2±9.0 to 38.2±29.4 ng/l), CBG (991.0±161.0 to 2332.0±428.0 nmol/l), and 5) no significant change of basal DHEA (24.6±15.7 to 22.6±11.7 μmol/l) and calculated basal value for free cortisol (22.8±14.9 to 19.2±6.9nmol/l). In conclusions, higher basal and ACTH-stimulated serum cortisol were found after three-month administration of COC, while basal and stimulated salivary cortisol were not significantly affected. Therefore, salivary cortisol can be used for assessment of adrenal function in women regularly using COC., K. Šimůnková, L. Stárka, M. Hill, L. Kříž, R. Hampl, K. Vondra., and Obsahuje bibliografii a bibliografické odkazy
This study investigated whether each part of the heart is evenly innervated by the left or right vagus and observed the mechanism of compensatory recovery after unilateral cervical vagotomy. HR, BP, LVSP and ±dp/dt max all decreased one week after left vagotomy, whereas only BP and -dp/dt max decreased one week after right vagotomy. We stern blot analyses revealed that the expression of M2 receptors in the left atrium and left ventricle was upregulated after subacute (1 week) left/right vagotomy. However, significantly more cholinesterase-positive nerves in LV and RV were seen one week after unilateral vagotomy compared to the sham-operated group. In addition, baroreflex sensitivity was increased after subacute right vagotomy. The decreasing effects of ACh (0.5 μ g/kg) on LVSP and ±dp/dt max (but not on HR and BP) were facilitated by subacute unilateral vagotomy. Our present experiments indicate that 1) the working myocardium is innervated bilaterally by the vagus, 2) ventricular contractility is influenced more by denervation of the left than the right vagus and 3) up-regulation of M2 muscarinic receptors in the left heart, increase of cholinergic nerves, and high baroreflex sensitivity could be involved in the mechanism of compensatory hemodynamic recovery via contralateral vagus overactivity, thereby amplifying contralateral vagal activity and decreasing cardiac contractility., L. N. Chen, W. J. Zang, X. J. Yu, J. Liu, D. L. Li, S. S. Kong, J. Lu, X. L. Xu., and Obsahuje bibliografii a bibliografické odkazy