Genetic component represents an important factor in the development of hypertension, which is known to be associated with changes in expression of vascular gap junction protein connexin 43 (Cx43). The aim of the study was to examine the distribution and expression of Cx43 in the aortic endothelium of adult normotensive Wistar rats (W), borderline hypertensive rats (BHR) and spontaneously hypertensive rats (SHR). Rings of the thoracic aorta were processed for immunofluorescence and Western blot analysis of endothelial Cx43 and for electron microscopy. Both, BHR and SHR exhibited significantly increased blood pressure vs. W (132±2 mm Hg and 185±3 mm Hg vs. 110±2 mm Hg). Reduced Cx43 immunofluorescence was observed in the endothelium of BHR and these alterations were more pronounced in SHR. Western blot analysis showed significant suppression of Cx43 expression in the aorta of both BHR (p<0.05) and SHR (p<0.001) vs. W. Electron microscopy revealed local subcellular alterations of interendothelial connections in BHR including extended tight junctions. These alterations were more frequent and marked in SHR. The results indicate that connexin 43 expression is reduced in the aortic endothelium already in prehypertensive period, which may affect cell-to-cell communication and thus participate in acceleration of hypertensive disease., K. Dlugošová, M. Mitašíková, I. Bernátová, P. Weismann, Ľ. Okruhlicová., and Obsahuje bibliografii a bibliografické odkazy
Elevated levels of glucocorticoids lead to the development of obesity and metabolic syndrome. Local glucocorticoid levels are regulated through the enzyme 11 β -hydroxysteroid dehydrogenase 1 (11 β -HSD 1), an enzyme that regenerates active cortisol from inert cortis one. Increased expression of 11 β - HSD 1 in adipose tissue promotes higher body mass index (BMI), insulin resistance, hypertension, and dyslipidemia. Human 11 β - HSD 1 is also responsible for inter-conversion of 7-hydroxylate metabolites of dehydroepiandrosterone (7-OH-DHEA) to their 7-oxo-form. To better understanding the mechanism of the action, we focused on 7-OH- and 7-ox o-DHEA, and their circulating levels during the reductive treatment in adolescent obese patients. We determined plasma levels of 7 α -OH-DHEA, 7 β -OH- DHEA, and 7-oxo-DHEA in 55 adolescent patients aged 13.04- 15.67 years, BMI greater than 90 th percentile. Samples were collected before and after one month of reductive therapy. Circulating levels of 7 α -OH-DHEA decreased during the reductive therapy from 1.727 (1.614; 1.854 , transformed mean with 95 % confidence interval) to 1.530 nm ol/l (1.435; 1.637, p<0.05) in girls and from 1.704 (1.583; 1. 842) to 1.540 nmol/l (1.435; 1.659, p<0.05) in boys. With regard to the level of 7-oxo-DHEA, a significant reduction from 1. 132 (1.044; 1.231) to 0.918 nmol/l (0.844; 1.000, p<0.05) was found after the treatment, but only in boys. No significant difference in 7 β -OH-DHEA levels was observed. In conclusions, diminished levels of 7 α -OH-DHEA indicate its possible effect on activity of 11 β -HSD 1. Further studies are necessary to clarify whether competitive substrates for 11 β -HSD 1 such as 7 α -OH-DHEA could inhibit production of glucocorticoids and may be involved in metabolic processes leading to reduction of obesity., L. Máčová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
We examined the involvement of phosphatidylinositol 3-kinase (PI3K) and its effector protein ki nase B (Akt) in cardioprotective effects of ischemic preconditioning (PC) with particular regards to its role in the protection against ischemia-induced arrhythmias in isolated perfused rat heart. PI3K/Akt inhibitor wortmannin (100 nM) was administered 15 min prior to 30-min regional (left anterior descending coronary artery occlusion) ischemia for the study of ischemic arrhythmias in the hearts perfused at constant coronary flow or prior to 30-min global ischemia followed by 2-h reperfusion for the infarct size (IS) determination (tetrazolium staining) in the hearts perfused at constant pressure. PC procedure (one cycle of isch emia/reperfusion, 5 min each) significantly reduced the total number of ventricular premature complexes (PVC) and severity of arrhythmias (arrhythmia score; AS) over the whole period of left anterior descending coronary artery occlusion in comparison with non-PC controls (PVC 166±40; AS 1.6±0.2 vs . 550±60 and 3.2±0.2; respectively; P<0.05). In a setting of global ischemia/reperfusion, PC decreased IS (in % of the left ventricle, LV) by 73 %. Pretreatment with wortmannin modified neither arrhythmogenesis nor IS in the non-PC hearts. Bracketing of PC with wortmannin did not abolish antiarrhythmic protection (PVC 92±25; AS 1.7±0.2; P<0.05 vs . non-PC hearts). On the other hand, wortmannin increased IS/LV in the PC hearts to 24±1.2 % as compared with 9 ± 0.6 % in the untreated ones (P<0.05). In conclusion, PI3K/Akt inhibition did not affect reduced arrhythmogenesis during ischemia in the PC hearts indicating that in contrast to its positive role in the irreversible myocardial injury, PI3K/Akt activity is not required for protection induced by PC against ischemic arrhythmias in the rat heart., T. Ravingerová, J. Matejíková, D. Pancza, F. Kolář., and Obsahuje bibliografii
Micropatterned surfaces have been used as a tool for controlling the extent and strength of cell adhesion, the direction of cell growth and the spatial distribution of cells. In this study, chemically micropattern ed surfaces were prepared by successive plasma polymerization of acrylic acid (AA) and 1,7-octadiene (OD) through a mask. Rat vascular smooth muscle cells (VSMC), bovine endothelial cells (EC), porcine mesenchymal stem cells (MSC) or human skeletal muscle cells (HSKMC) were seeded on these surfaces in densities from 9,320 cells/cm2 to 31,060 cells/cm2. All cell types adhered and grew preferentially on the strip-like AA domains. Between day 1 and 7 after seeding, the percentage of cells on AA domains ranged from 84.5 to 63.3 % for VSMC, 85.3 to 73.5 % for E, 98.0 to 90.0 % for MSC, and 93.6 to 55.0 % for HSKMC. The enzyme-linked immunosorbent assay (ELISA) revealed that the concentration of alpha-actin per mg of protein was significantly higher in VSMC on AA. Similarly, immunofluorescence staining of von Willebrand factor showed more apparent Weibel-Palade bodies in EC on AA domains. MSC growing on AA had better developed beta-actin cytoskeleton, although they were less stained for hyaluronan receptor (CD44). In accordance with this, MSC on AA contained a higher concentration of beta-actin, although the concentration of CD44 was lower. HSKMC growing on AA had a better developed alpha-actin cytoskeleton. These results based on four cell types suggest that plasma polymerization is a suitable method for producing spatially defined patterned surfaces for controlled cell adhesion, proliferation and maturation., E. Filová ... [et al.]., and Obsahuje seznam literatury
Stress exposure activates the sympathoneural system, resulting in catecholamine release. Chronic stress is associated with development of numerous disorders, including cardiovascular diseases. Here we investigated the expression of mRNAs for catecholamine biosynthetic enzymes tyrosine-hydroxylase, dopamine-ß-hydroxylase and phenylethanolamine N-methyl- transferase, and for ß1- and ß2-adrenoceptors in the right and left ventricles of rats exposed to chronic unpredictable mild stress. The tyrosine-hydroxylase and dopamine-ß-hydroxylase mRNA levels were not affected by stress, whereas the phenylethanolamine N-methyltransferase mRNA levels significantly increased in both right and left ventricles. No changes in ß1-adrenoceptor mRNA levels in either right or left ventricles were observed. At the same time, stress produced a significant increase of β2-adrenoceptor mRNA levels in left ventricles. These results suggest that elevated expression of phenylethanolamine N-methyltransferase in both ventricules and ß2-adrenoceptor genes in left ventricles could provide a molecular mechanism that leads to altered physiological response, which is important for the organism coping with stress., N. Spasojevic, L. Gavrilovic, S. Dronjak., and Obsahuje bibliografii a bibliografické odkazy
Cholesterol 7α-hydroxylase (CYP7A1), the key regulatory enzyme of bile acid synthesis, displays a pronounced diurnal variation. To better understand the regulation of CYP7A1 activity, three daylong examinations were carried out in 12 healthy men. The concentrations of 7α-hydroxycholest-4-en-3-one (C4), a surrogate marker of CYP7A1 activity, bile acids (BA), insulin, glucose, nonesterified fatty acids, triglycerides, and cholesterol were measured in serum in 90-min intervals from 7 AM till 10 PM. To lower and to increase BA concentration during the study, the subjects received cholestyramine and chenodeoxycholic acid (CDCA), respectively, in two examinations. No drug was used in the control examination. There was a pronounced diurnal variation of C4 concentration with a peak around 1 PM in most of the subjects. The area under the curve (AUC) of C4 concentration was five times higher and three times lower when subjects were treated with cholestyramine and CDCA, respectively. No relationship was found between AUC of C4 and AUC of BA concentration, but AUC of C4 correlated positively with that of insulin. Moreover, short-term treatment with cholestyramine resulted in about 10 % suppression of glycemia throughout the day. Our results suggest that insulin is involved in the regulation of diurnal variation of CYP7A1 activity in humans., J. Kovář ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Important fetal and perinatal pathologies, especially intrauterine growth restriction (IUGR), are thought to stem from placental hypoxia-induced vasoconstriction of the fetoplacental vessels, leading to placental hypoperfusion and thus fetal undernutrition. However, the effects of hypoxia on the fetoplacental vessels have been surprisingly little studied. We review here available experimental data on acute hypoxic fetoplacental vasoconstriction (HFPV) and on chronic hypoxic elevation of fetoplacental vascular resistance. The mechanism of HFPV includes hypoxic inhibition of potassium channels in the plasma membrane of fetoplacental vascular smooth muscle and consequent membrane depolarization that activates voltage gated calcium channels. This in turn causes calcium influx and contractile apparatus activation. The mechanism of chronic hypoxic elevation of fetoplacental vascular resistance is virtually unknown except of signs of the involvement of morphological remodeling., V. Hampl, V. Jakoubek., and Obsahuje seznam literatury
Expression of the muscle phenotype is the result of interaction between intrinsic and extrinsic factors, the latter including innervation, mechanical influences and hormonal signals. This minireview summarizes some of the current knowledge regarding the regulation of myosin heavy chain (MHC) isoform transitions during muscle development and regeneration. It describes the role of genetic factors, neural and mechanical influences and it focuses on the contribution of thyroid hormones to the differentiation of muscle fiber phenotypes as shown by the regulation of the expression of MHC isoforms and development of myofibrillar ATPase activity. Finally, it shortly summarizes results regarding the differentiation of MHC isoforms in regenerated muscle fibers of the graft after heterochronous isotransplantation in rats with different thyroid status., T. Soukup, I. Jirmanová., and Obsahuje bibliografii
We tested the effects of epidermal growth factor (EGF) on Na+/H+ exchanger (NHE) activity using urogastrone for treatment of Wistar rats and rat kidney tissue slices. NHE activity was monitored in isolated kidney brush border membrane vesicles by following fluorescence quenching of acridine orange. A significant increase of NHE activity was detected as early as 5 min after addition of urogastrone to rat kidney slices in vitro. In Wistar rats treated with urogastrone we also found increased NHE activity (by about 12 %). Both changes of NHE activity were the result of a significant rise of Vmax value and an apparent decrease in Km value in in vitro experiments. The rise of NHE activity caused by urogastrone was sensitive to the inhibitors of transcription and translation. The presence of phosphatase inhibitor, NaF, elevated NHE activity of non-stimulated as well as of urogastrone-stimulated exchanger, suggesting that phosphorylation plays an important role in Na+/H+ exchange. Osmolarity of the medium seems to regulate NHE activity in such a manner that both hyper- and hypoosmolar conditions inhibited NHE activity. The absence of Ca2+ions produced a 60 % decrease of NHE activity. The chemical modification of histidine residues with diethyl pyrocarbonate or SH groups with N-ethylmaleimide inhibited NHE activity., K. Barišić, O. Karužić, J. Petrik, T. Ž. Grubišić., and Obsahuje bibliografii
Sox3/SOX3 gene is considered to be one of the earliest neural markers in vertebrates. Despite the mounting evidence that Sox3/SOX3 is one of the key players in the development of the nervous system, limited data are available regarding the transcriptional regulation of its expression. This review is focused on the retinoic acid induced regulation of SOX3 gene expression, with particular emphasis on the involvement of retinoid receptors. Experiments with human embryonal carcinoma cells identified two response elements in volved in retinoic acid/retinoid X receptor-dependent activation of the SOX3 gene expression: distal atypical retinoic acid-response element, consisting of two unique G-rich boxes separated by 49 bp, and proximal element comprising DR-3-like motif, composed of two imperfect hexameric half-sites. Importantl y, the retinoic acid-induced SOX3 gene expression could be significantly down-regulated by a synthetic antagonist of retinoid receptors. This cell model provides a solid base for further studies on mechanism(s) underlying regulation of expression of SOX3 gene, which could improve the understanding of molecular signals that induce neurogenesis in the stem/progenitor cells both during development and in adulthood., G. Nikčević ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy