Vascular aging is associated with both structural and functional changes that can take place at the level of the endothelium, vascular smooth muscle cells and the extracellular matrix of blood vessels. With regard to the endothelium, reduced vasodilatation in response to agonists occurs in large conduit arteries as well as in resistance arteries with aging. Reviews concerning the different hypotheses that may account for this endothelial dysfunction have pointed out alterations in the equilibrium between endothelium-derived relaxing and constricting factors. Thus, a decreased vasorelaxation due to nitric oxide and, in some arteries, endothelium-derived hyperpolarizing factor as well as an increased vasoconstriction mediated by cyclooxygenase products such as thromboxane A2 are likely to occur in age-induced impairment of endothelial vasodilatation. Furthermore, enhanced oxidative stress plays a critical role in the deleterious effect of aging on the endothelium by means of nitric oxide breakdown due to reactive oxygen species. The relative contribution of the above phenomenon in age-related endothelial dysfunction is highly dependent on the species and type of vascular bed., R. L. Matz, C. Schott, J. C. Stoclet, R. Andriantsitohaina., and Obsahuje bibliografii
Hypertension-induced myocardial metabolic, structural and electrophysiological remodeling deteriorates with aging and contributes to both heart failure and occurrence of malignant arrhythmias. It has been shown in clinical trials that n-3 polyunsaturated fatty acids (n-3 PUFA) reduce the incidence of cardiovascular diseases and sudden cardiac death. We investigated the cardioprotective effects of n-3 PUFA in aged spontaneously hypertensive rats (SHR) and possible cellular mechanisms involved. Male and female 14-month-old SHR were fed with n-3 PUFA (Vesteralens, Norway, 20 mg/day for two months) and compared with untreated SHR. Results showed that n-3 PUFA supplementation led to 1) significant decline of blood pressure; 2) suppression of inducible ventricular fibrillation (VF) by 57 % (male) and 67 % (female) , although the arrhythmogenic substrates, like fibrosis, hypertrophy and abnormal gap junctions distribution were not eliminated; 3) preservation of the cardiomyocytes and the inte grity of their junctions; 4) enhancement of energetic metabolism enzyme activity; 5) augmentation of capillary density associated with increased alkaline phosphatase and decreased dipeptidyl peptidase-4 (DPP4) activity and 6/ increase in gap junction channel connexin-43 expression. Thus, aged male as well as female SHR benefit from n-3 PUFA supplementation that results in decrease in VF susceptibility, partly due to an improvement of myocardial metabolic state, cardiomyocyte and cell-to-cell junctions integrity and Cx43 up-regulation., M. Mitašíková, S. Šmidová, A. Mascaliová, V. Knezl, K. Dlugošová, Ľ. Okruhlicová, P. Weismann, N. Tribulová., and Obsahuje bibliografii a bibliografické odkazy
Mechanisms underlying atrial fibrillation (AF), the most common cardiac arrhythmia, particularly in aged population, are not fully elucidated. We have previously shown an increased propensity of old guinea pigs (GPs) heart to inducible AF when comparing to young animals. This study aimed to verify our hypothesis that susceptibility of aged heart to AF may be attributed to abnormalities in myocardial connexin-43 (Cx43) and extracellular matrix that affect cardiac electrical properties. Experiments were conducted on male and female 4-week-old and 24-week-old GPs. Atrial tissue was processed for analysis of Cx43 topology using immunohistochemistry, expression of Cx43 protein using immunobloting, and expression of mRNA of Cx43 and extracellular matrix metalloproteinase-2 (MMP-2) using real time PCR. Immunohistochemistry revealed uniform Cx43 distribution predominantly on lateral sides of the cardiomyocytes of young male and female GP atria. In contrast, non-uniform distribution, mislocalization and reduced immunolabeling of Cx43 were detected in atria of old GPs. In parallel, the atrial tissue levels of Cx43 mRNA were significantly decreased, while mRNA expression of MMP-2 was significantly increased in old versus young GPs. The changes were more pronounced in old GPs males comparing to females. Findings indicate that age-related down-regulation of atrial Cx43 and up-regulation of MMP-2 as well as disordered Cx43 distribution can facilitate development of AF in old guinea pig hearts., V. Nagibin, T. Egan Benova, C. Viczenczova, B. Szeiffova Bacova, I. Dovinova, M. Barancik, N. Tribulova., and Obsahuje bibliografii
Chronic airflow limitation, caused by chronic obstructive pulmonary disease (COPD) or by asthma, is believed to change the shape and the position of the diaphragm due to an increase in lung volume. We have made a comparison of magnetic resonance imaging (MRI) of diaphragm in supine position with pulmonary functions, respiratory muscle function and exercise tolerance. We have studied the differences between patients with COPD, patients with asthma, and healthy subjects. Most interestingly we found the lung hyperinflation leads to the changes in diaphragmatic excursions during the breathing cycle, seen in the differences between the maxim al expiratory diaphragm position (DPex) in patients with COPD and control group (p=0.0016) . The magnitude of the diaphragmatic dysfunction was significantly related to the airflow limitation expressed by the ratio of forced expiratory volume in 1 s to slow vital capacity (FEV 1 /SVC) , (%, p=0.0007); to the lung hyperinflation expressed as the ratio of the residual volume to total lung capacity (RV/TLC), (%, p=0.0018) and the extent of tidal volume constrain expressed as maximal tidal volume (V Tmax ), ([l], p=0 .0002); and the ratio of tidal volume to slow vital capacity (VT/SVC), (p=0.0038) during submaximal exercise. These results suggest that diaphragmatic movement fails to contribute sufficiently to the change in lung volume in emphysema. Tests of respiratory muscle function were related to the position of the diaphragm in deep expiration, e.g. neuromuscular coupling (P 0.1 /VT) (p=0.0232). The results have shown that the lung volumes determine the position of the diaphragm and function of the respiratory muscles. Chronic airflow limitation seems to change the position of the diaphragm, which thereafter influences inspiratory muscle function and exercise tolerance. There is an apparent relationship between the position of the diaphragm and the pulmonary functions and exercise tolerance., L. Hellebrandová, J. Chlumský, P. Vostatek, D. Novák, Z. Rýznarová, V. Bunc., and Obsahuje bibliografii
Because greater Akt substrate of 160 kDa (AS160) phosphorylation has been reported in insulin-stimulated skeletal muscles without improved Akt activation several hours post-exercise, we hypothesized that prior exercise would result in attenuated AS160 dephosphorylation in insulin-stimulated rat skeletal muscle. Epitrochlearis muscles were isolated from rats that were sedentary (SED) or exercised 3 h earlier (3 h postexercise; 3hPEX). Paired muscles were incubated with [3H]-2-deoxyglucose (2-DG) without insulin or with insulin. Lysates from other insulin-stimulated muscles from SED or 3hPEX rats were evaluated using AS160Thr642 and AS160Ser588 dephosphorylation assays. Prior exercise led to greater 2-DG uptake concomitant with greater AS160Thr642 phosphorylation and a non-significant trend (P=0.087) for greater AS160Ser588. Prior exercise also reduced AS160Thr642 and AS160Ser588 dephosphorylation rates. These results support the idea that attenuated AS160 dephosphorylation may favor greater AS160 phosphorylation post-exercise., E. B. Arias, H. Wang, G. D. Cartee., and Seznam literatury
Considerable evidence demonstrates that phenotypic switching of vascular smooth muscle cells (VSMCs) is influenced by aging and hypertension. During phenotypic switching, VSMCs undergo a switch to a proliferative and migratory phenotype, with this switch being a common pathology in cardiovascular diseases. The aim of this study was to explore the joint influence of age and hypertension on thoracic aortic smooth muscle phenotypic switching and the balance of Akt and mitogen-activated protein kinase (MAPK) signaling during this switch. Different ages of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were used to establish hypertension and aging models. The phenotypic state was determined by detecting the marker proteins α-SM-actin, calponin, and osteopontin (OPN) via immunohistochemical staining and Western blot. Signaling proteins associated with the Akt and MAPK pathways were detected in rat thoracic aorta using Western blot. Both aging and hypertension caused a decrease in contractile (differentiated) phenotype markers (α-SM-actin and calponin), while the synthetic (proliferative or de-differentiated) phenotype maker was elevated (OPN). When combining hypertension and aging, this effect was enhanced, with Akt signaling decreased, while MAPK signaling was increased. These results suggested that VSMCs phenotype switching is modulated by a balance between Akt and MAPK signaling in the process of aging and hypertension., Lin Zhang, Zhaoxia Xu, Ying Wu, Jingwen Liao, Fanxing Zeng, Lijun Shi., and Obsahuje bibliografii
Alcohol abuse during pregnancy is a well-known factor in fetal morbidity, including smaller fetal size. We have shown that chronic hypoxia, considered the main pathogenetic factor in intrauterine growth restriction, elevates fetoplacental vascular resistance (and vasoconstrictor reactivity) and thus, presumably, reduces placental blood flow. We thus hypothesized that alcohol may affect the fetus - in addition to other mechanisms - by altering fetoplacental vascular resistance and/or reactivity. Using isolated, double-perfused rat placenta model, we found that maternal alcohol intake in the last third of gestation doubled the vasoconstrictor responses to angiotensin II but did not affect resting vascular resistance. Reactivity to acute hypoxic challenges was unchanged. Chronic maternal alcohol intake in a rat model alters fetoplacental vasculature reactivity; nevertheless, these changes do not appear as serious as other detrimental effects of alcohol on the fetus., V. Jakoubek, V. Hampl., and Obsahuje bibliografii
Aldosterone plays a key role in maintaining the homeostasis of the whole organism. Under some circumstances, aldosterone can contribute to the progression of cardiovascular diseases, including coronary artery disease. This study demonstrates that aldosterone associates negatively with some lipidogram parameters and positively with the concentration of homocysteine. These associations are characteristic for coronary artery disease and are not present in control subjects. The findings also indicate that in vitro aldosterone stimulates homocysteine production by rat adrenal glands, which may explain the associations observed with coronary artery disease. Moreover, we have found that aldosterone significantly modulates in vitro platelet reactivity to arachidonate and collagen - aldosterone increases the pro-aggregatory action of collagen, but decreases the pro-aggregatory potential of arachidonate. Therefore, the findings of these in vitro and ex vivo experiments indicate the existence of new pathways by which aldosterone modulates lipid- homocysteine- and platelet-dependent atherogenesis., K. Karolczak, P. Kubalczyk, R. Glowacki, R. Pietruszynski, C. Watala., and Seznam literatury
Nitrogen-containing bisphosphonates were found to inhibit farnesyl diphosphate synthase - an essential enzyme in the cholesterol biosynthesis pathway, but their effect on cholesterol synthesis per se in the central nervous system (CNS) remains unknown. The aim of the present study was to examine possible influence of a representative agent alendronate on cholesterol synthesis rates in selected parts of rat CNS and on plasma cholesterol level. Two groups of rats were orally administered either alendronate (3 mg/kg b.w. ) or vehicle for 9 days. At the end of experiment, brain (basal ganglia, frontal cortex and hippocampus) and spinal cord were isolated and cholesterol synthesis was determined using the technique of deuterium incorporation from deuterated wa ter. In the alendronate group significant reductions of choleste rol synthesis rates were detected in frontal cortex, hippocampus and spinal cord (p<0.001). However, the experimental treatment did not produce a significant alteration in the levels of plasma cholesterol. In conclusion, this study brings the first experimental evidence of the inhibition of cholesterol biosynthesis with alendronate in central nervous system., Ľ. Cibičková, R. Hyšpler, N. Cibiček, E. Čermáková, V. Palička., and Obsahuje bibliografii
Growth factors are powerful molecules that regulate cellular growth, proliferation, healing, and cellular differentiation. A delivery matrix that incorporates growth factors with high loading efficiencies, controls their release, and maintains bioactivity would be a powerful tool for regenerative medicine. Alginate has several unique properties that make it an excellent platform for the delivery of proteins. Mild gelling conditions can minimize the risk of protein denaturation; moreover, alginate can serve as protection from degradation until protein release. Various modifications have been proposed to tune alginate binding and release proteins, simultaneously adjusting alginate degradability, mechanical stiffness, swelling, gelation properties and cell affinity. The primary objective of this article is to review the literature related to recent advances in the application of alginate matrices in protein delivery in regenerative medicine. A special emphasis is put on the relevance of delivery of growth factors and chemokine., E. Wawrzyńska, D. Kubies., and Obsahuje bibliografii