We evaluated the effects of N G -nitro-L-arginine methylester (L-NAME) (50 mg/kg/day) and 7-nitroindazole (7NI) (10 mg/kg/day) administered from 10th-16th week of age either individually or together on cardiovascular system of Wistar rats and SHR. Systolic blood pressure (sBP) was measured weekly by the plethysmographic method. For morphological studies, the animals (n=10) were perfused with a fixative (120 mm Hg), and thoracic aorta and carotid and co ronary arteries were processed for electron microscopy. For functional investigation (n=10), aortic rings were used in an or gan bath. In Wistar rats, L-NAME evoked an increase of sBP; hype rtrophy of the heart and arterial walls; an increase in cross-sectional areas (CSA) of endothelial cells (EC), muscle cells (SMC), extracellular matrix (ECM), and a decrease in acetylcholin e-induced endothelial-dependent relaxation (EDR). 7NI evoked sBP-independent hypotrophy of the heart and arterial walls, a decrease in CSA of EC and SMC without affecting the CSA of ECM, and a mild decrease in acetylcholine-induced EDR. 7NI and L-NAME administered together evoked lower effect on BP and trophicity of the heart and all arteries, and a similar de crease in acetylcholine-induced EDR compared to L-NAME alone. In SHR, 7NI did not evoke any effect on the studied parameters., F. Kristek, M. Drobna, S. Cacanyiova., and Obsahuje bibliografii
Nitric oxide generated from L-arginine is a messenger for cell- to-cell communication. Abnormalities in nitric oxide release have been implicated in diseases ranging from hypertension and atherosclerosis to septic shock and rheumatoid arthritis. We report here the in vivo and in vitro measurements of nitric oxide in the cardiovascular system using a porphyrinic sensor specific for NO. The sensor has a detection limit 10“9 M, response time of 0.1-10 ms and diameter of 1-20 fi m. Protected by an intravenous catheter or Swan-Ganz catheter, the sensor can be implanted into tissues as well as into the blood stream. Nitric oxide concentrations were measured directly in the heart and also in veins and arteries, ranging in diameter from 100 nm to 5 mm. Nitric oxide production was induced by the action of different physical agents (shear stress, stretching) as well as various chemical substances agonists (bradykinin, acetylcholine, ATP).
We report here the in vitro measurements of nitric oxide in the cardiovascular system using a porphyrinic sensor specific for NO. Nitric oxide concentrations were measured directly in different parts of the heart and also in different arteries and veins, ranging from 100 /um to 5 mm in diameter. Highest NO * concentrations were found in the heart and particularly in the areas of aortic and pulmonary valves. The NO * concentration in the arteries was higher than in the veins. A clearcut positive correlation was obtained by plotting the vessel diameter and production of nitric oxide.
Treatment with pertussis toxin (PTX) which eliminates the activity of Gi proteins effectively reduces blood pressure (BP) and vascular resistance in spontaneously hypertensive rats (SHR). In this study we have compared the functional characteristics of isolated arteries from SHR with and without PTX-treatment (10 μg/kg i.v., 48 h before the experiment). Rings of thoracic aorta, superior mesenteric artery and main pulmonary artery were studied under isometric conditions to measure the reactivity of these vessels to receptor agonists and to transmural electrical stimuli. We have found that the treatment of SHR with PTX had no effect on endothelium-dependent relaxation of thoracic aorta induced by acetylcholine. In PTX-treated SHR, the maximum contraction of mesenteric artery to exogenous noradrenaline was reduced and the dose-response curve to cumulative concentration of noradrenaline was shifted to the right. Similarly, a reduction in the magnitude of neurogenic contractions elicited by electrical stimulation of perivascular nerves was observed in the mesenteric artery from PTX-treated SHR. PTX treatment of SHR also abolished the potentiating effect of angiotensin II on neurogenic contractions of the main pulmonary artery. These results indicate that PTX treatment markedly diminishes the effectiveness of adrenergic stimuli in vasculature of SHR. This could importantly affect BP regulation in genetic hypertension., A. Zemančíková, J. Török, J. Zicha, J. Kuneš., and Obsahuje bibliografii a bibliografické odkazy
Pulse wave analysis permits non-invasive assessment of arterial elasticity indices. The contour varies in different parts of the circulation. It depends on physiological or pathophysiological conditions of the organism. The pathological events like arteriosclerosis or diabetes have a primary effect to the artery elasticity. Hypertension or some heart diseases al so influence the pulse wave velocity and resulted in earlier wave reflections. There are several methods of pulse wave measurements based on different principles and depending on the type of measured pulse wave. The evaluation parameters can be assessed from the time domain, derivations, velocity or frequency domain. The main aim of this review article is to offer a recent overview of pulse wave measurement parameters and main results obtained. The principles of pulse wave measurement and current experience in clinical practice are shortly discussed too., D. Korpas, J. Hálek, L. Doležal., and Obsahuje seznam literatury
To test whether macrophages can play any role in hypoxic pulmonary vasoconstriction, we tested the in vitro response of rings from small pulmonary arteries to the activation of macrophages by FMLP, a substance stimulating predominantly membrane-bound NADPH oxidase. A small vessel myograph was used to measure the responses of rings from small pulmonary arteries (300-400 μ m) isolated from rat lungs. Rings from 5 rats were placed into both chambers of the myograph. The vessels were stabilized for 40 min and then normalized by automatic stretching to a wall tension equivalent to the intravascular pressure 30 mm Hg. At the start of each experiment, vessels were exposed to 80 mM K + to obtain maximal contractile response, which was used to normalize subsequent contractile responses. 2x10 6 viable macrophages, obtained by peritoneal lavage, were added into one chamber, then 5 μ M FMLP was administrated to both chambers and the tension measurement was started. The hydrogen peroxide concentration produced by stimulated macrophages was measured luminometrically. The concentrations of H 2 O 2 in specimens from chambers containing activated macrophages rose from 3.5±1.5 nM to 110±28 nM within 25 min of stimulation, while FMLP itself didn’t increase the H 2 O 2 concentration from the baseline value (4.5±3 nM) in samples from control chambers. After FMLP administration, the tension of the vessel rings in the presence of macrophages reached 0.23±0.07 of maximal contractile response, it did not change in controls. The additi on of ROS scavenger 4-hydroxy- TEMPO blocked the contractile response to the activation of macrophages. We conclude that the activation of macrophages stimulates the contraction of small pulmonary arteries and that this contraction is probably mediated by reactive oxygen species., M. Žaloudíková, J. Herget, M. Vízek., and Obsahuje bibliografii a bibliografické odkazy
The aim of this study was to obtain a detailed analysis of the relationship between the finger arterial compliance C [ml/mm Hg] and the arterial transmural pressure Pt [mm Hg]. We constructed a dynamic plethysmograph enabling us to set up a constant pressure Pcss [mm Hg] and a superimposed fast pressure vibration in the finger cuff (equipped with a source of infra-red light and a photoelectric sensor for the measurement of arterial volume). Pcss could be set on the required time interval in steps ranging between 30 and 170 mm Hg, and on sinusoidal pressure oscillation with an amplitude Pca (2 mm Hg) and a frequency f (20, 25, 30, 35, 40 Hz). At the same time continuous blood pressure BP was measured on the adjacent finger (Portapres). We described the volume dependence of a unitary arterial length on the time-varying transmural pressure acting on the arterial wall (externally Pcss+Pca.sin(2πf), internally BP) by a second-order differential equation for volume. This equation was linearized within a small range of selected BP. In the next step, a Fourier transform was applied to obtain the frequency characteristic in analytic form of a complex linear combination of frequency functions. While series of oscillations [Pca, f] were applied for each Pcss, the corresponding response of the plethysmogram was measured. Amplitude spectra were obtained to estimate coefficients of the frequency characteristic by regression analysis. We determined the absolute value: elastance E, and its inverse value: compliance (C=1/E). Then, C=C(Pt) was acquired by applying sequences of oscillations for different Pcss (and thus Pt) by the above-described procedure. This methodology will be used for the study of finger arterial compliance in different physiological and pathological conditions., J. Moudr, J. Svačinová, E. Závodná, N. Honzíková., and Obsahuje bibliografii