Chronic continuous light exposure leads to melatonin deficiency along with complex neurohumoral activation resulting in hypertension development in rats. The aim of this study was to show, whether continuous light in duces fibrotic rebuilding of the aorta and whether the treatment with melatonin or angiotensin converting enzyme inhibitor captopril can prevent these potential alterations. In a six-week experiment, 3-month-old Wistar rats were divided into 4 groups (t en per group): controls, rats exposed to continuous light, exposed to continuous light plus treated with captopril (100 mg/kg/24 h) and exposed to continuous light plus treated with melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP) and collagen type I and III in the media of thoracic aorta were me asured. Continuous light induced hypertension and fibrotic rebuilding of the aorta in terms of enhancement of collagen I and III concentration in the aortic media. Both captopril and melatonin prevented SBP rise and reduced collagen III concentration in the aorta. However, only melatonin reduced collagen I and the sum of collagen I and III in the aortic tissue. We conclude that in continuous light-induced hypertension, administration of melatonin, along with SBP reduction, decreases collagen I and III concentration in the aorta. It is suggested that antifibrotic effect of melatonin may reduce the stiffness of the aorta and small arteries and beneficially influence the nature of the pulse wave and peripheral vascular resistance., K. Repová-Bednárová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The aim of the present study was to determine the effect of angiotensin-converting enzyme inhibitor captopril on cGMP and cAMP concentration in the left ventricle and aorta after NO synthase inhibition by 4-week-lasting NG-nitro-L-arginine-methyl ester (L-NAME) treatment. Five groups of rats were investigated: controls, L-NAME in the dose 20 mg/kg/day (L-NAME 20), L-NAME in the dose 40 mg/kg/day (L-NAME 40), captopril in the dose 100 mg/kg/day, L-NAME 40 mg/kg/day together with captopril 100 mg/kg/day. Captopril completely prevented L-NAME-induced hypertension and LV hypertrophy development. Compared to the controls, cGMP concentration in the L-NAME 20 and L-NAME 40 groups was decreased by 13 % and 22 %, respectively, in the left ventricle and by 27 % and 56 % in the aorta, respectively. Captopril did not influence this decrease of cGMP concentration. Cyclic AMP concentration in the aorta of L-NAME 20 group increased by 17 %. In the L-NAME 40 group, cAMP concentration increased by 17 % in the left ventricle and by 34 % in the aorta compared to controls. This increase was enhanced in rats given L-NAME together with captopril. Captopril alone had no effect on cAMP concentration. We conclude that captopril does not affect the concentration of cGMP, however, it has more than the additive effect on the cAMP concentration increase in the cardiovascular system during long-term NO synthase inhibition., O. Pecháňová, I. Bernátová., and Obsahuje bibliografii
Angiotensin converting enzyme inhibitors are widely used in therapy of cardiovascular diseas es. However, the consensus on effects of these inhibitors in control of myocardial oxygen consumption during the process of experimental hypercholesterolemia and under the condition of endothelial dysfunction has not been reached. Here we examined effects of captopril, an angiotensin converting enzyme inhibitor, on serum lipid levels and oxygen consumption rate in mitochondria isolated from heart of rabbits treated by hypercholesterolemic diet. During the twelve-week period, th e Chinchilla male rabbits were daily treated by saline (controls); 1 % cholesterol diet; 5 mg/kg/day captopril or 1 % cholesterol + 5 mg/kg/day captopril. Total- and high-densi ty lipoprotein cholesterol and triglyceride in serum were measured spectrophotometricly. The left ventricle mitochondrial fraction was isolated and myocardial oxygen consumption was measur ed by Biological Oxygen Monitor. Mitochondria isolated from hearts of rabbits exposed to hypercholesterolemic diet sh owed significantly reduced respiration rates (state 3 and state 4) with altering adenosine diphosphate/oxygen ratio, whereas the respiratory control ratio was not affected when compared to controls. Mitochondria from cholesterol/captopril-treated animals showed significantly reduced respiration rates without altering adenosine diphosphate/oxygen ratio index or respiratory control ratio. Although captopril did not exert the favorable effect on serum lipid levels in cholesterol-treated animals, it restored the mitochondrial oxygen consumption. Further studies should be performed to define the under lying physiological and/or pathophysiological mechanisms and clinical implications., Z. Kojic ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The aim of our study was to evaluate the efficacy of FK506, mycophenolate mofetil (MM) and aminoguanidine (AMG) on infiltration of macrophages (MPHs), neutrophils (NPHs) and dendritic cells (DC) into corneal grafts during the early phases after transplantation (Tx). Tx was performed in mice (C57BL/10 to BALB/c). Therapy included FK506 (0.2 mg/kg), MM (30 mg/kg) or AMG (0.1 g/kg), started at the day of Tx and was injected i.p. daily. Corneas were excised on the 3rd and 7th day after Tx. Immunohistological evaluation using antibodies against MPHs, NPHs and DC was performed and corneal grafts were assessed in the periphery and in central part of the cornea separately. On the 3rd day after Tx, a massive infiltration of MPHs and NPHs into corneal grafts was revealed; the DC in filtration was lower in all treated groups. Treatment with FK506 and MM led to a significant reduction of NPHs in the centers of the grafts, but not of MPHs. In contrast, AMG significantly reduced MPHs migration into allografts on the third day after Tx, whereas NPHs infiltration has not been attenuated. However, immunosuppressants had no influence on the infiltration of DC during early phases after Tx., P. Bysterská, P. Svozílková, H. Farghali., and Obsahuje bibliografii a bibliografické odkazy
Stellate ganglion blockade (SGB) with a local anesthetic increases muscle sympathetic nerve activity in the tibial nerve in humans. However, whether this sympathetic excitation in the tibial nerve is due to a sympathetic blockade in the neck itself, or due to infiltration of a local anesthetic to adjacent nerves including the vagus nerve remains unknown. To rule out one mechanism, we examined the effects of cervical sympathetic trunk transection on renal sympathetic nerve activity (RSNA) in anesthetized rats. Seven rats were anesthetized with intraperitoneal urethane. RSNA together with arterial blood pressure and heart rate were recorded for 15 min before and 30 min after left cervical sympathetic trunk transection. The baroreceptor unloading RSNA obtained by decreasing arterial blood pressure with administration of sodium nitroprusside was also measured. Left cervical sympathetic trunk transection did not have any significant effects on RSNA, baroreceptor unloading RSNA, arterial blood pressure, and heart rate. These data suggest that there was no compensatory increase in RSNA when cervical sympathetic trunk was transected and that the increase in sympathetic nerve activity in the tibial nerve during SGB in humans may result from infiltration of a local anesthetic to adjacent nerves rather than a sympathetic blockade in the neck itself., T. Ikeda ... [et al.]., and Obsahuje seznam literatury
It is documented that in chronic hypertensive state there is an increased vasodepressor response to calcium channel antagonists such as the dihydropyridine derivate nifedipine. This effect is generally proportional to initial blood pressure as was demonstrated in several models of experimental hypertension. In the present study we investigated the effect of chronic nifedipine treatment on the development of cardiovascular system in young spontaneously hypertensive rats (SHR) in order to evaluate whether it could prevent the abnormalities leading to hypertensive state. Four- and eight-week-old rats were treated with nifedipine (50 mg/kg/day) for 4 weeks. Blood pressure of nifedipine-treated SHR remained at the initial level in contrast to their untreated controls where it continued to increase. In both age groups, chronic nifedipine administration reduced neurogenic contractions of isolated superior mesenteric artery, but did not significantly affect the dose-response curve to exogenous noradrenaline in 8-week-old rats. In contrast, maximum response to noradrenaline was significantly attenuated in mesenteric artery of 12-week-old nifedipine-treated SHR. We can presume that the antihypertensive effect of nifedipine is similar in both stages of spontaneous hypertension development, but the mechanisms involved might be different. It seems that chronic reduction of calcium influx during the rapid phase of pathological blood pressure increase in SHR may eliminate the effect of enhanced sympathetic tone, which may have unfavorable consequences on cardiovascular structure and function., A. Zemančíková, J. Török., and Obsahuje seznam literatury
Phenobarbital is an anticonvulsive drug widely used in newborns with hypoxic-ischemic encephalopathy. The objective of our study was to describe possible effect of frequently co-administered medications (dopamine, dobutamine, norepinephrine, furosemide, phenytoin, and analgesics) on the phenobarbital pharmacokinetics in full term newborns with hypoxic-ischemic encephalopathy. Phenobarbital pharmacokinetic parameters (standardized intravenous loading dose was 10-20 mg/kg, maintenance dose 2-6 mg/kg/day) were computed using non-compartmental analysis. Co-medication was evaluated throughout the whole treatment period up to 5 days. Volume of distribution, clearance, and half-life median values (95 % CI) for phenobarbital in the whole study population (n=37) were 0.48 (0.41-0.56) l/kg, 0.0034 (0.0028-0.0040) l/h/kg, and 93.7 (88.1-99.2) h, respectively. Phenobarbital pharmacokinetic parameters were not significantly affected by vasoactive drugs (dopamine, dobutamine, and norepinephrine), furosemide, phenytoin, or analgesics. Furthermore, no dose-dependent alteration of phenobarbital pharmacokinetic parameters was noted for vasoactive medication at doses equivalent to cumulative vasoactive-inotropic score (area under the curve in a plot of vasoactive-inotropic score against time) 143.2-8473.6, furosemide at cumulative doses of 0.2-42.9 mg/kg, or phenytoin at cumulative doses of 10.3-46.2 mg/kg. Phenobarbital pharmacokinetics was not affected by investigated co-administered drugs used in newborns with hypoxic-ischemic encephalopathy in real clinical settings., M. Šíma, P. Pokorná, K. Hronová, O. Slanař., and Obsahuje bibliografii
The objective of this study was to evaluate the effect of diet and 677 C®T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene on plasma homocyst(e)ine concentrations in an adolescent population (113 males, age: 14.2±2.4 years; 202 females, age: 14.9±2.1 years) from a region characterized by high cardiovascular mortality. Homocyst(e)ine levels did not differ between males and females (9.4±3.5 and 8.9±3.1 mmol/l, respectively). The homozygosity for the 677 C®T MTHFR mutation was found in 4.6 % of subjects. No differences in homocyst(e)ine levels were found between MTHFR genotypes. Analysis of the diet composition which was performed on a 24-hour daily recall basis and a food frequency questionnaire showed a low daily intake of vitamin B6 (males: 1.13 mg/66 % RDA; females: 0.92 mg/61 % RDA). Daily folic acid intake was 0.21 g/105 % RDA in males and 0.23 g/115 % RDA in females. The results of our study show that the high homocyst(e)ine levels in the adolescent population were not affected by the 677 C®T MTHFR mutation. We conclude that an insufficient dietary intake of vitamin B6 and folic acid is responsible for this finding. This is in accord with the recommendation that the dietary allowances for folate should be reset to the originally prescribed levels of 0.4 g/day which should be sufficient to control the homocysteine levels., K. Rašlová, A. Bederová, J. Gašparovič, P. Blažíček, B. Smolková., and Obsahuje bibliografii
a1_The effect of different muscle shortening velocity was studied during cycling at a pedalling rate of 60 and 120 rev.min-1 on the [K+]v in 21 healthy young men (aged 22.5±2.2 years, body mass 72.7±6.4 kg, VO2max 3.720±0.426 l . min-1) performing an incremental exercise test until exhaustion. The power output increased by 30 W every 3 min, using an electrically controlled ergometer Ergoline 800S (see Zoladz et al. J. Physiol. 488: 211-217, 1995). The test was performed twice: once at a cycling frequency of 60 rev.min-1 (test A) and a few days later at frequency of 120 rev.min-1 (test B). At rest and at the end of each step (i.e. the last 15 s) antecubital venous blood samples for [K+]v were taken. Gas exchange variables were measured continuously (breath-by-breath) using Oxycon Champion Jaeger. The pre-exercise [K+]v in both tests was not significantly different amounting to 4.24±0.36 mmol.l-1 in test A, and 4.37±0.45 mmol.l-1 in test B. However, the [K+]v during cycling at 120 rev.min-1 was significantly higher (p<0.001, ANOVA for repeated measurements) at each power output when compared to cycling at 60 rev.min-1. The maximal power output reached 293±31 W in test A which was significantly higher (p<0.001) than in test B, which amounted to 223±40 W. The VO2max values in both tests reached 3.720±0.426 l.min-1 vs 3.777±0.514 l.min-1. These values were not significantly different. When the [K+]v was measured during incremental cycling exercise, a linear increase in [K+]v was observed in both tests. However, a significant (p<0.05) upward shift in the [K+]v and a % VO2max relationship was detected during cycling at 120 rev.min-1. The [K+]v measured at the VO2max level in tests A and B amounted to 6.00±0.47 mmol.l-1 vs 6.04±0.41 mmol.l-1, respectively., a2_This difference was not significant. It can thus be concluded that a) generation of the same external mechanical power output during cycling at a pedaling rate of 120 rev.min-1 causes significantly higher [K+]v changes than when cycling at 60 rev.min-1, b) the increase of venous plasma potassium concentration during dynamic incremental exercise is linearly related to the metabolic cost of work expressed by the percentage of VO2max (increase as reported previously by Vollestad et al. J. Physiol. Lond. 475: 359-368, 1994), c) there is a tendency towards upward shift in the [K+]v and % VO2max relation during cycling at 120 rev.min-1 when compared to cycling at 60 rev.min-1., J. A. Zoladz, K. Duda, J. Majerczak, P. Thor., and Obsahuje bibliografii
Replacing SAFAs (saturated fatty acids) for vegetable PUFAs (polyunsaturated fatty acids) has a well documented positive effect on the lipoprotein pattern while the direct effect of dietary fatty acids composition on systemic inflammation remains to be proven. In well controlled randomised cross-over study with 15 overweight/obese postmenopausal women, the effect of dietary switch on systemic inflammation was investigated. A two 3 weeks dietary period either with predominant animal fat (SAFA, 29 caloric % SAFA) or vegetable fat (PUFA 25 % caloric % PUFA) were interrupted by wash-out period. The expected increasing effect on SAFA diet to LDL-C (low density cholesterol) and opposite effect of PUFA diet was documented following changes in fatty acid spectrum in VLDL (very low density cholesterol) particles. The switch from SAFA diet to PUFA diet produced a significant change of CRP (C-reactive protein) concentration (p<0.01) whereas similar trend of IL-18 did not reach statistical significance. In this study, previous in vitro results of different SAFA and PUFA proinflammatory effects with well documented molecular mechanisms were first proven in a clinical study. It could be stated that the substantial change of dietary fatty acid composition might influence proinflammatory effect in addition to traditional cardiovascular risk factors., I. Králová Lesná, ... [et al.]., and Obsahuje seznam literatury