High blood pressure (BP) of L-NAME hypertensive rats is maintained not only by the absence of nitric oxide (NO)-dependent vasodilatation but also by the enhancement of both sympathetic and angiotensin II-dependent vasoconstriction. The aim of the present study was to evaluate the role of inhibitory G (Gi) proteins, which are involv ed in tonic sympathetic vasoconstriction, in the pathogenesis of NO-deficient hypertension. We therefore studied BP response to chronic L-NAME administration (60 mg/kg/day for 4 weeks) in rats in which the in vivo inactivation of Gi proteins was induced by injection of pertussis toxin (PTX, 10 μg/kg i.v.). The impairment of sympathetic vasoconstriction due to PTX-induced Gi protein inactivation prevents the full development of NO-deficient hypertension because BP of PTX-treated rats subjected to chronic L-NAME administration did not reach hypertensive values. Nevertheless, chronic NO synthase inhibition per se is capable to increase moderately BP even in PTX-treated rats. Our data suggest that the sympathetic vasoconstriction is essential for the development of established NO-deficient hypertension., J. Zicha ... [et al.]., and Obsahuje seznam literatury
Little is known about the effect of chronic angiotensin-converting enzyme inhibition on the catecholamine levels in fowls. In this study, we investigated the effects of chronic lisinopri1 dihydrate (Ld) application on the plasma levels of adrenaline and noradrenaline and on the blood pressure. Lisinopril was given in different concentrations (25, 75 and 250 mg/l drinking water) to the white Leghorn chickens for 9 weeks, while the control group drank tap water only. Twenty-eight hours after the last lisinopril application, arterial blood pressure (BP), plasma adrenaline and noradrenaline levels, plasma renin (PRA) and plasma angiotensin-converting enzyme (ACE) activities were determined. In all concentrations, lisinopril significantly increased PRA and decreased ACE activities. Arterial BP was decreased only in the group receiving high lisinopril concentration (Controls 119±10.27, Ld3 98±5.4 mm Hg). However, the lower lisinopril concentrations did not alter arterial BP compared to the control group. Plasma noradrenaline levels were decreased in a concentration-dependent manner (47-58 %), but plasma adrenaline levels remained unchanged. The heart weight/body weight ratio was not changed in any of the lisinopril-treated groups. The persistent decrease in the blood pressure after lisinopril treatment was not directly related to a decrease of plasma ACE activity or plasma noradrenaline levels. Its mechanism still remains to be elucidated., H. S. Ozdemir, H. E. Aksulu, F. Karataş, B. Ustündag, I. Bingöl., and Obsahuje bibliografii
The Vasotrac monitor provides non-invasive near-continuous blood pressure monitoring and is designed to be an alternative to direct intra-arterial blood pressure (BP) measurement. As compared to radial artery invasive BP and upper arm noninvasive BP, Vasotrac readings have been found to have a good agreement with them. However, discrepancies have been reported when rapid changes in BP exist. In the present study we compared BP measured by the Vasotrac monitor on the radial artery with that recorded on the finger arteries by the differential oscillometric device allowing measurement on the beat-to-beat basis. Comparisons were performed on the mean arterial pressure (MAP) level. Special attention was paid to the signal conditioning before comparison of pressures of different temporal resolution. Altogether 383 paired MAP measurements were made in 14 healthy subjects. Based on all 383 paired measurements, the MAP values measured at the radial artery at rest were 4.8±6.0 mm Hg higher than those measured on fingers. The observed difference between the Vasotrac and differential oscillometric device can be explained by different measurement sites. This result is consistent with previous investigations, and the Vasotrac monitor can be considered to adequately track relatively rapid MAP changes on the radial artery. Attention should be paid to a proper signal conditioning before comparison of results obtained by different devices., K. Jagomägi ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The aim of the study was to assess the association between promoter polymorphism [A(-596)G] in interleukin-6 gene and office systolic and diastolic blood pressures, and the heart rate (HR) in apparently healthy Czech subjects. Furthermore, we evaluated the possible influence of gender, BMI and smoking on these supposed associations. An age-matched (40-50 years) and gender-matched (F/M=81/89) sample of apparently healthy Czech subjects (n=170, F/M=81/89) without hypertension, other cardiovascular diseases or diabetes was examined. The A(-596)G Il-6 gene polymorphism was detected by the PCR method. No differences in genotype distribution and/or allelic frequency was found between groups with lower systolic blood pressure (£ 122 mm Hg) and higher systolic blood pressure (> 122 mm Hg). Similarly, no differences in the IL-6 polymorphism were found between lower (£ 86 mm Hg) and higher (> 86 mm Hg) diastolic blood pressure groups. However, we proved a significant increase of genotypes AG+GG as well as the allele (-596)G in higher (>78 beats/min) heart rate group. The genotypes AG+GG represent significantly higher relative risk for higher HR frequency, especially in women. Among lean persons with a low heart rate frequency, fewer AG+GG genotypes were determined than among any other subjects. The genotypes AG+GG are more frequent in non-smoking persons with higher HR compared to non-smoking subjects with lower HR, especially in women. Gender, BMI and smoking substantially modify the distribution of A(-596)G Il-6 gene polymorphism in apparently healthy persons with lower or higher heart rate., A. Vašků, M. Souček, M. Goldbergová, J. Vácha., and Obsahuje bibliografii
We studied the relationship between blood pressure (BP), body mass index (BMI, kg/m2) and baroreflex sensitivity (BRS, ms/mmHg) in adolescents. We examined 34 subjects aged 16.2±2.4 years who had repeatedly high causal BP (H) and 52 controls (C) aged 16.4±2.2 years. Forty-four C and 22 H were of normal weight (BMI between 19-23.9), and 8 C and 12 H were overweight (BMI between 24-30). Systolic BP was recorded beat-to-beat for 5 min (Finapres, controlled breathing 0.33 Hz). BRS was determined by the cross-spectral method. The predicting power of BMI and BRS for hypertension was evaluated by sensitivity, specificity, and receiver operating curve (ROC - plot of sensitivity versus specificity). H compared with C had lower BRS (p<0.01) and higher BMI (p<0.05). Multiple logistic regression analysis (p<0.001) revealed that a decreased BRS (p<0.05) and an increased BMI (p<0.01) were independently associated with an increased risk of hypertension. No correlation between BMI and BRS was found either in H or in C. Following optimal critical values by ROC, the sensitivity, specificity and area under ROC were determined for: BMI - 22.2 kg/m2, 61.8 %, 69.2 %, 66.0 %; BRS - 7.1 ms/mmHg, 67.7 %, 69.2 %, 70.0 %; BMI and BRS - 0.439 a.u., 73.5 %, 82.7 %, and 77.3 %. Decreased BRS and overweight were found to be independent risk factors for hypertension., K. Krontorádová, N. Honzíková, B. Fišer, Z. Nováková, E. Závodná, H. Hrstková, P. Honzík., and Obsahuje bibliografii a bibliografické odkazy
The objective of the current study was to search for genetic determinants associated with antihypertensive effects of angiotensin-converting enzyme (ACE) inhibitor captopril. Linkage and correlation analyses of captopril-induced effects on blood pressure (BP) with renal transc riptome were performed in the BXH/HXB recombinant inbred (RI) strains derived from spontaneously hypertensive rat (SHR) and Brown Norway (BN-Lx) progenitors. Variability of blood pressure lowering effects of captopril among RI strains was continuous suggesting a polygenic mode of inheritance. Linkage analysis of captopril- induced BP effects revealed a significant quantitative trait locus (QTL) on chromosome 15. This QTL colocalized with cis regulated expression QTL (eQTL) for the Ednrb (endothelin receptor type B) gene in the kidney (SHR allele was associated with increased renal expression) and renal expression of Ednrb correlated with captopril-induced BP effects. These results suggest that blood pressure lowering effects of ACE inhibitor captopril may be modulated by the variants at the Ednrb locus., J. Zicha ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
We investigated non-invasively cardiac contractility and autonomic nervous activity during presyncopal orthostatic stress induced in healthy humans. A graded orthostatic stress (GOS) paradigm, consisting of head-up tilt (HUT) combined with lower body negative pressure (LBNP) of increasing magnitude, was used to reach a presyncopal end-point in 15 healthy adults. Continuous beat-to-beat hemodynamic and autonomic parameters were recorded. From supine control (C1) to presyncope (PS), total peripheral resistance index (TPRI) decreased from 2300±500 to 1910±320 dyne*s*m²/cm^5 (p=0.004), index of contractility (IC) from 59±14 to 27±6 1000/s (p<0.0001), left ventricular working index (LVWI) from 5.2±1.3 vs. 3.6±0.6 mmHg*L/(min*m²) (p=0.0001) and acceleration index (ACI) from 65±18 vs. 54±15 100/s² (p=0.04). Low frequency variation of diastolic blood pressure (LFnudBP) increased from 51±14 to 67±11 % (p=0.0006) and of systolic blood pressure (LFnusBP) from 50±6 vs. 67±8 % (p<0.0001). High frequency variation of RR-interval (HFms²RRI) decreased from 385±320 to 38±43 ms² (p=0.001). From late GOS (G3) to PS, TPRI decreased from 2540±640 to 1910±320 dyne*s*m²/cm^5 (p=0.003), IC from 35±6 to 27±6 1000/s (p=0.003), LVWI from 4.6±0.9 to 3.6±0.6 mmHg*L/(min/m²) (p=0.003), LFnusBP from 71±8 to 67±8 % (p=0.03), LFmmHg²dBP from 6.6±4.0 to 4.8±2.9 mmHg² (p=0.0001), LFmmHg²sBP from 9.7±7.8 to 7.4±4.8 mmHg² (p=0.01). HFnuRRI increased from 19±8 to 28±13 % (p=0.008). Myocardial contractility indices and parameters of sympathetic activity were reduced in the presyncopal state, while parasympathic activity was increased. This suggests a decrease in cardiac contractility during orthostatically induced presyncope in healthy subjects., E. K. Grasser, N. Goswami, H. Hinghofer-Szalkay., and Obsahuje seznam literatury
Pulse transit time (PTT), the interval between ventricular electrical activity and peripheral pulse wave, is assumed to be a surrogate marker for blood pressure (BP) changes. The objective of this study was to analyze PTT and its relation to BP during cardiopulmonary exercise tests (CPET). In 20 patients (mean age 51±18.4 years), ECG and finger-photoplethysmography were continuously recorded during routine CPETs. PTT was calculated for each R-wave in the ECG and the steepest slope of the corresponding upstroke in the plethysmogram. For each subject, linear and non-linear regression models were used to assess the relation between PTT and upper-arm oscillometric BP in 9 predefined measuring points including measurements at rest, during exercise and during recovery. Mean systolic BP (sBP) and PTT at rest were 128 mm Hg and 366 ms respectively, 197 mm Hg and 289 ms under maximum exercise, and 128 mm Hg and 371 ms during recovery. Linear regression showed a significant, strong negative correlation between PTT and sBP. The correlation between PTT and diastolic BP was rather weak. Bland-Altman plots of sBP values estimated by the regression functions revealed slightly better limits of agreements for the non-linear model (-10.9 to 10.9 mm Hg) than for the linear model (-13.2 to 13.1 mm Hg). These results indicate that PTT is a good potential surrogate measure for sBP during exercise and could easily be implemented in CPET as an additional parameter of cardiovascular reactivity. A non-linear approach might be more effective in estimating BP than linear regression., T. Wibmer, K. Doering, C. Kropf-Sanchen, S. Rüdiger, I. Blanta, K. M. Stoiber, W. Rottbauer, C. Schumann., and Obsahuje bibliografii
The development of neurogenic pulmonary edema (NPE) can be elicited by an immediate epidural balloon compression of the thoracic spinal cord. To evaluate whether a slower balloon inflation could prevent NPE development, we examined the extent of NPE in animals lesioned with a rapid (5 μl - 5 μl - 5 μl) or slow rate (3 μl - 2 μl - 2 μl - 2 μl - 2 μl - 2 μl - 2 μl) of balloon inflation. These groups were compared with the NPE model (immediate inflation to 15 μl) and with healthy controls. Slow balloon inflation prevented NPE development, whereas the pulmonary index and histology revealed a massive pulmonary edema in the group with a rapid rate of balloon inflation. Pulmonary edema was preceded by a considerable decrease in heart rate during the inflation procedure. Moreover, rapid inflation of balloon in spinal channel to either 5 μl or 10 μl did not cause NPE. Thus, a slow rate of balloon inflation in the thoracic epidural space prevents the development of neurogenic pulmonary edema, most likely due to the better adaptation of the organism to acute circulatory changes (rapid elevation of systemic blood pressure accompanied by profound heart rate reduction) during the longer balloon inflation period. It should be noted that spinal cord transection at the same level did not cause neurogenic pulmonary edema., J. Šedý ... [et al.]., and Obsahuje seznam literatury
Arterial wall stiffness is considered an independent cardiovascular risk factor. Aim of this study was to evaluate relationship between clinical, 24-hour, average day-time and night-time blood pressure (BP) and measures of arterial stiffness assessed by pulse wave velocity (PWV) (using SphygmoCor applanation tonometer) in essential hypertension (severe-resistant (RH, n=29) and moderate hypertension (EH, n=35)) and in normotensive control subjects (n-29) (NCS) matched by age. After multiple regression analysis, PWV remains significantly correlated mainly with night-time pulse pressure and to a lesser extent with age. PWV was significantly higher in RH compared to moderate EH and NCS., J. Rosa, B. Štrauch, O. Petrák, T. Pikus, R. Holaj, T. Zelinka, D. Wichterle, J. Widimský Jr., and Obsahuje bibliografii a bibliografické odkazy