The contrasting pattern of cardiac inotropy induced by human peptide endothelin-1 (ET-1) has not been satisfactorily explained. It is not clear whether ET-1 is primarily responsible for increased myocardial ET-1 expression and release with resultant inotropic effects, or for the induction of myocardial hypertrophy and heart failure. There are at least two subtypes of endothelin receptors (ETA and ETB) and the inotropic effects of ET-1 differ depending on the receptor involved. Along with some other groups, we reported significant subtype-ETB endothelin receptor down-regulation in human cardiac cells preincubated with endothelin agonists (Dřímal et al. 1999, 2000). The present study was therefore designed to clarify the subtype-selective mechanisms underlying the inotropic response to ET-1 and to its ETB-selective fragment (8-21)ET-1 in the isolated rat heart. The hearts were subjected to (1-21)ET-1 and to (8-21)ET-1, or to 30 min of stop-flow ischemia followed by 40 min of reperfusion, both before and after selective blockade of endothelin receptors.The present study revealed that both peptides, ET-1 and its (8-21)ET-1 fragment, significantly reduced coronary blood flow in nmolar and higher concentrations. The concomitant negative inotropy and chronotropy were marked after ET-1, while the infusion of the ET-1(8-21) fragment produced a slight but significant positive inotropic effect. Among the four endothelin antagonists tested in continuous infusion only the non-selective PD145065 and ETB1/B2-selective BQ788 (in mmolar concentrations) slightly reduced the early contractile dysfunction of the heart induced by ischemia, whereas ETA-selective PD155080 partially protected the rat heart on reperfusion., J. Dřímal, V. Knezl, J. Dřímal Jr , D. Dřímal, K. Bauerová , V. Kettmann, A.M. Doherty , M. Štefek., and Obsahuje bibliografii
Pyridoxal isonicotinoyl hydrazone (PIH) is a new tridentate Fe-chelating agent that should be very promising in many pathological states resulting from both an iron-overload and formation of free radicals. The aim of our study was to investigate the effect of PIH on the cardiovascular system focusing to the regulatory protein - cardiac troponin T (cTnT). The study was carried out in two groups of Chinchilla male rabbits: 1) PIH (50 mg/kg dissolved in 10 % Cremophor i.p., once a week, 10 administrations, n=8) and 2) Cremophor (2 ml/kg i.p. in the same schedule, n=7). Plasma concentrations of cTnT (as a marker of myocardial damage) were measured using a commercial kit (Roche). cTnT was within the physiological range (i.e. < 0.1 mg/l) during the whole experiment in the Cremophor group. In the PIH group, the cTnT levels were not significantly increased when compared with the control group or with the initial values (except with those before the 5th administration). Furthermore, we analyzed the cytosolic and myofibrillar fraction of cTnT in the left ventricular myocardium. Using SDS-PAGE and Western blot we resolved three isoforms. The profiling of TnT did not differ significantly between the PIH-treated group and the Cremophor-treated group. Our data concerning cTnT support the opinion that the possible cardiotoxicity of PIH is very low., M. Adamcová, J. Macháčková, V. Geršl, V. Pelouch, T. Šimůnek, I. Klimtová, R. Hrdina, P. Poňka., and Obsahuje bibliografii
Cardicola langeli n. sp. (Digenea: Aporocotylidae) infects the heart of sheepshead, Archosargus probatocephalus (Walbaum, 1792) (Perciformes: Sparidae) in the northern Gulf of Mexico off Horn Island (type locality), Mississippi, USA. The new species is described herein using light and scanning electron microscopy of adult specimens and can be most easily distinguished from the other 24 accepted species of Cardicola Short, 1953 by the combination of having (i) an ovovitelline duct that extends anteriad and that (ii) is posterior to the ootype, (iii) a male genital pore that is lateral to the oviducal seminal receptacle and (iv) a female genital pore lateral to the ootype. The new species is the only member of Cardicola so-far reported to have tegumental spines that are distally flattened and broad, rather than pointed. The new species generally resembles the two other species of Cardicola that infect sparids, i.e. Cardicola cardiocolum (Manter, 1947) (type species) from jolthead porgy, Calamus bajonado (Block et Schneider), in the Gulf of Mexico and Cardicola aurata Holzer, Montero, Repullés, Sitja-Bobadilla, Alvarez-Pellitero, Zarza et Raga, 2008, from gilthead seabream, Sparus aurata Linnaeus, in the Mediterranean Sea, by having a spheroid anterior sucker with concentric rows of minute spines anterior to the mouth and by having a similar general arrangement of the vitellarium, gonads and genitalia. However, it differs from them by having the combination of the aforementioned five features plus asymmetrical posterior caeca and a dextral posterior caecum that extends beyond the posterior margin of the ovary. Probable eggs of C. langeli n. sp. that contain a ciliated miracidium infect gill epithelium and are spheroid. An updated list of hosts, infection sites and geographic localities for the 25 accepted species of Cardicola is provided.
The effect of chronic hypercapnia on cardioprotection induced by chronic hypoxia was investigated in adult male Wistar rats exposed to isobaric hypoxia (10 % O2) for three weeks. In the first experimental group, CO2 in the chamber was fully absorbed; in the second group, its level was increased to 4.1 %. Normoxic controls were kept in atmospheric air. Anesthetized open-chest animals were subjected to 20-min LAD coronary artery occlusion and 3-h reperfusion for infarct size determination (TTC staining). Chronic hypoxia alone reduced body weight and increased hematocrit; these effects were significantly attenuated by hypercapnia. The infarct size was reduced from 61.9 ± 2.2 % of the area at risk in the normoxic controls to 44.5±3.3 % in the hypoxic group (P<0.05). Hypercapnia blunted the infarct size-limiting effect of hypoxia (54.8±2.4 %; P<0.05). It is concluded that increased CO2 levels in the inspired air suppress the development of the chronic hypoxia-induced cardioprotective mechanism, possibly by interacting with ROS signalling pathways., J. Neckář, O. Szárszoi, J. Herget, B. Ošťádal, F. Kolář., and Obsahuje bibliografii
The purpose of this study was to assess the endocrine status, thoracic impedance, blood concentration, and hemodynamic dose-responses using different angles of passive head-up tilt (HUT) ranging from 12° to 70° in the same subjects. Measurements were performed during 20 min supine position (pre-HUT), 30 min upright (HUT12, HUT30, HUT53, or HUT70), and 20 min supine (post-HUT); subjects 70 min in the supine position only (HUT0) served as resting controls. Norepinephrine increased above resting control values by 19, 44, 80, and 102 %; epinephrine by 30, 41, 64, and 68 %; aldosterone by 29, 62, 139, and 165 %; plasma renin activity n. s., 41, 91, and 89 %; vasopressin n.s., 27, 47, and 59 %; thoracic bioimpedance n. s., 8, 13, and 16 %; heart rate n. s., 5, 26, and 45 %, and mean arterial pressure n. s., 5, 7, and 10 %; at min 27 of HUT12, HUT30, HUT53, and HUT70, respectively. Pulse pressure decreased with HUT53 and HUT70 by 4 and 10 %. Hematocrit increased by 0.2, 1.7, 6.3, and 7.2 %, respectively. Blood density increased by 2.3 and 3.0 g/l, plasma density by 1.7 and 1.8 g/l with HUT53 and HUT70. After finishing HUT, heart rate fell to values which stayed below pre-HUT, and also below resting control levels for ł 5 min ("post-orthostatic bradycardia") even after the lowest orthostatic load (HUT12). Thoracic impedance and arterial pressure remained increased after terminating HUT30, HUT53, and HUT70. In conclusion, passive orthostatic loading of different extent produces specific dose-responses of different magnitude in the endocrine system, blood composition, thoracic impedance, and hemodynamic variables. The heart rate is depressed even after HUT12, while arterial blood pressure and thoracic impedance exceed pre-stimulus levels after greater head-up tilt, indicating altered cardiovascular response after passive orthostasis., Z. László, A. Rössler, H. G. Hinghofer-Szalkay., and Obsahuje bibliografii
Present study was aimed to investigate sympathetic responses to mental stress with hypothesis that the presence of obesity in patients with hypertension has a modifying effect. Young male subjects, 8 with hypertension grade I, with BMI<25 kg/m2 (HT), 10 with hypertension grade I, and BMI>30 kg/m2 (HT OB), 14 healthy controls with BMI<30 kg/m2 (OB), and 13 healthy controls with BMI<25 kg/m2 (C) underwent the Stroop test. ECG was recorded continuously to evaluate heart rate variability (HRV). Blood pressure (BP) and catecholamine concentrations were measured at baseline, at the end of mental stress test and 15 min thereafter. Patients with HT demonstrated increased adrenaline concentrations and enhanced stress-induced noradrenaline release compared to that in healthy controls. In obese subjects, stress-induced increase of systolicBP was lower compared to lean individuals. Stress exposure induced a significant rise in the low frequency power component of HRV, however the increase was lower in the HT OB group compared to C. Obesity in patients with hypertension did not lead to a different reaction in comparison with lean hypertensive subjects. The present data demonstrate higher sympathoadrenal activity in early-stage of hypertension. Obesity is connected with higher resting systolicBP and modifies the HRV response to mental stress., A. Garafova, A. Penesova, E. Cizmarova, A. Marko, M. Vlcek, D. Jezova., and Obsahuje bibliografii
Our aim was to test the hypothesis that the occurrence of extrasystoles in higher decennia is proportional to the altitude. The occurrence of supraventricular (SVPB) and ventricular (VEB) extrasystoles, values of systolic and diastolic blood pressure and the heart rate were studied in 20 healthy elderly men (50-64 years) during cable cabin transportation to a moderate altitude. These values were measured in stations located at 898 m, 1764 m, and 2632 m above sea level during the transportation in both directions. Our records show that the values of blood pressure and heart rate were within normal limits during the whole period of transportation. Both SVPB and VEB were increasing during the ascent and decreasing to the initial values during the descent compared to the values at altitude of 898 m. The highest values (6 to 7-times exceeding the initial ones) were measured at the summit. The results have demonstrated that the occurrence of SVPB and VEB is proportional to the altitude. The increased incidence in the number of extrasystoles is suggested to be mediated by beta-adrenoceptors., Š. Kujaník, M. Sninčák, K. Galajdová, K. Racková., and Obsahuje bibliografii
a1_The question was addressed of how nitric oxide synthase (NO synthase) inhibition-induced hypertension in rat parents would affect the cardiovascular system in their offsprings. Two experimental groups were set up: Group I - offsprings of parents who had both been administered NO synthase inhibitor L-nitro-arginine methyl ester (L-NAME 40 mg/kg/day) for 5 weeks, the treatment of dams continued till week 12. Group II - offsprings fed by dams administered L-NAME after delivery only for a period of 4 weeks. Control age-matched offsprings formed the third group. Blood pressure and heart rate in parents and in 3-week-old offsprings were determined noninvasively. In the offsprings, body and heart weight were measured and the heart/body weight ratio (HW/BW) was calculated. The NO synthase activity, and also ornithine decarboxylase activity as a marker of polyamine production, were determined in the heart. The acetylcholine-induced relaxation of aortic rings was also followed. A marked blood pressure increase with a tendency to a decreased heart rate was found in the offsprings of Group I. A significant decrease in heart weight and body weight with a decreased HW/BW ratio indicated cardiac hypotrophy that contrasted with the decrease in NO synthase activity and increase in ornithine decarboxylase activity in the heart. Noteworthy was also the finding of completely preserved relaxation of the aorta to acetylcholine. Offsprings of Group II were similarly characterized by significantly higher blood pressure, a tendency to decreased heart rate, a decrease in heart weight, but not of the HW/BW ratio. The contrasting findings of heart weight decrease on the one hand and NO synthase activity decrease and ornithine decarboxylase increase on the other, were also found in this group. Full relaxation of the aorta to acetylcholine was preserved., a2_It can be concluded that remarkable alterations in the cardiovascular system were found in offsprings of hypertensive NO compromised parents., M. Gerová, I. Bernátová, J. Török, M. Juráni., and Obsahuje bibliografii