We studied the effect of thiazide-like diuretic – indapamide on fibrosis development in the left ventricle of young spontaneously hypertensive rats (SHR) and assessed the involvement of nitric oxide in this process. Six-week-old male SHR were treated with indapamide (1 mg/kg/day) for six weeks. Age-matched SHR were used as hypertensive and Wistar-Kyoto rats (WKY) as normotensive control. Systolic blood pressure was measured by tail-cuff plethysmography. Nitric oxide synthase (NOS) activity, protein expressions of endothelial (eNOS) and inducible NOS (iNOS), myocardial fibrosis and collagen type I and III were determined in the left ventricle. Indapamide treatment partially prevented SBP increase in SHR (SHR+Indapamide: 157±4, SHR: 171±3, WKY: 119±3 mmHg). Indapamide prevented myocardial fibrosis development in SHR, but without affecting collagen type I to type III ratio. Indapamide did not affect NOS activity as well as eNOS and iNOS protein expressions in the left ventricles evaluated by both Western blot and immunohistochemically. In conclusion, our results indicate that indapamide-induced prevention of myocardial fibrosis is not mediated by nitric oxide-related mechanism., P. Janega, S. Kojšová, L. Jendeková, P. Babál, O. Pecháňová., and Obsahuje bibliografii a bibliografické odkazy
a1_We analyzed fiber type composition of soleus and extensor digitorum longus (EDL) muscles of 3- to 19-month-old male and female inbred Lewis rats using histochemical demonstration of mATPase activity. The rats were divided into four groups of the mean age of 3, 6, 9 and 14 months. We found that the soleus muscle of 3-month-old rats contained significantly more of fast 2A fibers and less of slow type 1 fibers compared to older rats, while no significant difference was found between female and male rats at any age group. In contrast, we found no significant difference in the EDL fiber type composition among the age groups, but we found that the EDL muscle of female rats contained significantly less 2A fibers and more 2B fibers than that of male animals. Our results thus revealed an age difference in the soleus muscle and a sex difference in the EDL muscle among postnatal Lewis rats. The number of slow type 1 fibers in the soleus muscle varied between 87 and 100 % and that of 2A fibers between 13 and 0 %. In the EDL the percentage of type 1 fibers varied between 2.6 and 8.7 %, that of 2A fibers between 12.6 and 25.8 % and that of 2B fibers between 70.4 and 81.6 %. Both muscles thus exhibited a considerable degree of variability among individual animals even in the same age group. Furthermore, a comparison of the Lewis rats with literature data of other rat strains showed that the number of fast 2A fibers in the soleus muscle of 4-month-old and older animals decreased in this order: SHR > Lister Hooded > Fisher 344 > Sprague- Dawley > Wistar > WBN/Kob > Lewis strain, being almost 20 % in the SHR and less than 2 % in the Lewis rats. In contrast, the “fastest” composition (judged according to the percentage of the fastest 2B fibers) of the EDL muscle was demonstrated by Lewis, Wistar and Fisher 344 rats (about 75 %), while Sprague-Dawley and WBN/Kob rats contained only about 50 % of 2B fibers., a2_The percentage of slow type 1 fibers in the EDL was low in all strains (about 5 %). Our results thus show that the individual, age and sex as well as inter-strain differences in muscle fiber type composition should not be ignored when comparing results of different studies. We also demonstrated that the inbred Lewis strain appears to have more “specialized” muscle composition, as its soleus is the “slowest” and its EDL is the “fastest” among the routinely used rat strains., P. Novák, G. Zachařová, T. Soukup., and Obsahuje bibliografii a bibliografické odkazy
Induction of the inducible form of nitric oxide synthase (iNOS) in the vascular and cardiac tissue by several inflammatory stimuli may result in the production of large amounts of nitric oxide (NO) for a sustained period. Recent data obtained in the rat aorta in which iNOS was induced by lipopolysaccharide (LPS) have demonstrated that adventitial cells represent the main site of NO production. Adventitial-derived NO can exert an immediate down-regulatory effect on smooth muscle contraction (via activation of the cyclic GMP pathway) but may also initiate longer lasting effects through the formation of NO stores within the medial layer. One candidate for such NO stores are dinitrosyl non-heme iron complexes. Low molecular weight thiols interact with preformed NO stores and promote vasorelaxation by a cyclic GMP-independent mechanism involving the activation of potassium channels. In the heart, the induction of iNOS is involved in delayed protection against ischemia-reperfusion-induced functional damages. Recent data obtained with monophosphoryl lipid A, a non-toxin derivative of LPS, strongly suggest that iNOS-derived NO in the rat heart does not act as an immediate mediator of the cardioprotection but rather as a trigger of long-term protective mechanisms. Thus, the present data reveal the important role of adventitial cells as a site of iNOS expression and activity in intact blood vessels. The induction of adaptive mechanisms in the heart and the formation of releasable NO stores in blood vessels are examples of long-term consequences of iNOS induction. These new information are relevant for a better understanding of the circumstances in which NO overproduction by iNOS may play either a beneficial or deleterious role in these tissues., B. Muller, A. L. Kleschyov, K. Gyorgy, J.-C. Stoclet., and Obsahuje bibliografii
Angiogenesis is known to be triggered by various stimuli including hypertension. It was previously found that NO-deficient hypertension is accompanied by structural remodeling of the cardiac muscle and large coronary arteries. This study was aimed to examine the qualitative subcellular alterations of capillaries in the heart of the rats treated with L-NAME (40 mg/kg/day for 4 weeks). The results showed that long-lasting inhibition of NO production induced an apparent activation of fibroblast function. This was associated with enhancement of fibrozation as well as with the induction of angiogenesis. Accordingly, fibroblasts were frequently located in the vicinity of capillary pericytes, which was followed by their detachment and migration. Moreover, besides inactive or even injured capillaries, the other ones exhibited extensive proteosynthetic activity linked to capillary growth, proliferation and migration of endothelial cells. The results strongly indicate enhanced triggering of the angiogenesis in L-NAME-induced NO-deficient hypertension., Ľ. Okruhlicová, N. Tribulová, I. Bernátová, O. Pecháňová., and Obsahuje bibliografii
MicroRNAs are emerging as important regulators of cardiac function. This study investigated the role of microRNA-24 (miR-24) in ischemic cardiomyocytes, based on the observation that miR-24 expression was significantly enhanced in the ischemic myocardium of rats. Using primary cultured rat cardiomyocytes, cell injury was induced by ischemic conditions, and the cells were evaluated for changes in lactate dehydrogenase (LDH) release, cell viability, apoptosis and necrosis. The results showed that miR-24 was increased in myocytes exposed to ischemia. When miR-24 was further overexpressed in ischemic myocytes using the mimic RNA sequence, LDH release was reduced, cell viability was enhanced, and apoptosis and necrosis rates were both decreased. By contrast, a deficiency in miR-24 resulted in the largest LDH release, lowest cell viability and highest apoptosis and necrosis rates in normal and ischemic myocytes, with significant changes compared to that of non-transfected myocytes. Additionally, the mRNA and protein levels of the pro-apoptotic gene, BCL2L11, were down-regulated by miR-24 overexpression and up-regulated by miR-24 deficiency. The luciferase reporter assay confirmed BCL2L11 to be a target of miR-24. Overall, this study showed a protective role for miR-24 against myocardial ischemia by inhibiting BCL2L11, and may represent a potential novel treatment for ischemic heart disease., D.-F. Li ... [et al.]., and Obsahuje seznam literatury
The aim of our study was to test the hypothesis, whether repeated allopurinol pre-treatment (in dose of 135 mg/kg s.c.) can influence changes of brain excitability caused by long-term hypoxia exposition in young immature rats. Rat pups were exposed together with their mother in to an intermittent hypobaric hypoxia (simulated altitude of 7 000 m) since the day of birth till the 11th day (youngest experimental group) or 17th day for 8 hours a day. Allopurinol was administered daily immediately before each hypoxia exposition. The duration of evoked afterdischarges (ADs) and the shape of evoked graphoelements were evaluated in 12, 18, 25 and 35-day-old freely moving male pups. Hypobaric hypoxia prolonged the duration of ADs in 12, 18 and 25-day-old rats. The ADs were prolonged in 35-day-old rats only after the first stimulation. Allopurinol shorted the duration of ADs only in 12-day-old pups. In older experimental group the effect of allopurinol treatment was less pronounced., K. Jandová, ... [et al.]., and Obsahuje seznam literatury
The present study was undertaken to evaluate the use of cortisol 6b-hydroxylation in defining the effect of amiodarone on cytochrome CYP3A activity. To accomplish this goal, the in vivo activity of CYP3A was estimated by measuring the 24-hour urinary excretion of 6b-hydroxycortisol (6b-OHC) and by calculating 24-hour ratio of 6b-hydroxycortisol to urinary free cortisol (6b-OHC/UFC ratio). Nine cardiac patients scheduled for amiodarone treatment were recruited to participate in this study. Urine was collected over a 24-hour period from each subject before the first amiodarone administration and during the third day of oral administration of amiodarone (200 mg four times daily as a loading dose). Three days of amiodarone treatment caused a significant decrease (p<0.05) in both the 6b-OHC/UFC ratio and the 24-hour urinary excretion of 6b-OHC. These results suggest that amiodarone is an inhibitor of CYP3A activity., S. Mičuda, M. Hodač, L. Šišpera, P. Pařízek, M. Pleskot, G. Zimová, J. Cerman, J. Martínková, V. Pinderman., and Obsahuje bibliografii
We studied the effects of administration of b-resorcylidene aminoguanidine (RAG) to Wistar strain rats with experimental diabetes mellitus (DM) induced by streptozotocin. The effects studied included antioxidant levels in plasma and the liver, oxidative damage of lipids represented by the formation of substances reacting with thiobarbituric acid (TBARP) and selected biochemical indicators. The administration of RAG did not significantly affect antioxidant status of diabetic rats or hemoglobin glycation and plasma concentration of fructosamine. In diabetic rats, application of RAG decreased formation of TBARP in plasma but not in the liver. Moderate steatosis of liver and increased plasma levels of triacylglycerols in diabetic rats were significantly improved by application of RAG., A. Liptáková, J. Čársky, O. Uličná, O. Vančová, P. Božek, Z. Ďuračková., and Obsahuje bibliografii
Poly-(lactide-co-glycolide) (PLGA) is an FDA-approved biodegradable polymer which has been widely used as a scaffold for tissue engineering applications. Collagen has been used as a coating material for bone contact materials, but relatively little interest has focused on biomimetic coating of PLGA with extracellular matrix components such as collagen and the glycosaminoglycan chondroitin sulfate (CS). In this study, PLGA films were coated with collagen type I or collagen I with CS (collagen I/CS) to investigate the effect of CS on the behaviour of the osteoblastic cell line MG 63. Collagen I/CS coatings promoted a significant increase in cell number after 3 days (in comparison to PLGA) and after 7 days (in co mparison to PLGA and collagen-coated PLGA). No influence of collagen I or collagen I/CS coatings on the spreading area after 1 day of culture was observed. However, the cells on collagen I/CS formed numerous filopodia and displayed well developed vinculin-containing focal adhesion plaques. Moreover, thes e cells contained a significantly higher concentration of osteocalcin, measured per mg of protein, than the cells on the pure collagen coating. Thus, it can be concluded that collagen I/CS coatings promote MG 63 cell proliferation, improve cell adhesion and enhance osteogenic cell differentiation., M. Vandrovcová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy