Magnetic resonance imaging has been used for evaluating of a brain edema in experimental animals to assess cytotoxic and vasogenic edema by the apparent diffusion coefficient (ADC) and T2 imaging. This paper brings information about the effectiveness of methylprednisolone (MP) on experimental brain edema. A total of 24 rats were divided into three groups of 8 animals each. Rats with cytotoxic/intracellular brain edema induced by water intoxication were assigned to the group WI. These rats also served as the additional control group CG when measured before the induction of edema. A third group (WIMP) was intraperitoneally administered with methylprednisolone 100 mg/kg during water intoxication treatment. The group WI+MP was injected with methylprednisolone 50 mg/kg into the carotid artery within two hours after the water intoxication treatment. We evaluated the results in four groups. Two control groups (CG, WI) and two experimental groups (WIMP, WI+MP). Rats were subjected to MR scanning 24 h after edema induction. We observed significantly increased ADC values in group WI in both evaluated areas - cortex and hippocampus, which proved the occurrence of experimental vasogenic edema, while ADC values in groups WIMP and WI+MP were not increased, indicating that the experimental edema was not developed and thus confirming the protective effect of MP., Petr Kozler, Vít Herynek, Dana Marešová, Pablo D. Perez, Luděk Šefc, Jaroslav Pokorný., and Obsahuje bibliografii
a1_The day-night variation of food intake and alkaline phosphatase (AP) activity was studied in the duodenum of rats neonatally treated with monosodium glutamate (MSG) and saline-treated (control) rats. The animals were kept under light-dark conditions (light phase from 09:00 h to 21:00 h) with free access to food. AP activity was cytophotometrically analyzed in the brush-border of enterocytes separated from the tip, middle and cryptal part of the villi every 6 h over a 24-hour period. In comparison with the controls, MSG-treated rats consumed about 40 % less food during the dark period and their 24-hour food intake was thus significantly lowered (P<0.001). On the other hand, the nocturnal feeding habit showed a similar pattern: food consumption was high during the night (65 % vs. 75 %) and the lowest consumption was found during the light phase (35 % vs. 25 %) in MSG-treated and control rats, respectively. In agreement with the rhythm of food intake, the highest AP activity was observed during the dark phase and was lowest during the light phase in both groups of animals. These significant day-night variations showed nearly the same pattern in the enterocytes of all observed parts along the villus axis. In comparison with the controls, a permanent increase of AP activity was observed in neonatal MSG-treated rats. This increase was more expressive during the dark phase of the day in the cryptal (P<0.001) and middle part of the villus (P<0.01). From the viewpoint of feeding, this enzyme in MSG-treated rats was enhanced in an inverse relation to the amount of food eaten i.e. despite sustained hypophagia the mean AP activity in the enterocytes along the villus axis was higher than in the control animals during all investigated periods., a2_The present results suggest that the increased AP activity in MSG-treated rats is probably not a consequence of actual day-night eating perturbations but could be a component of a more general effect of MSG. This information contributes to better understanding of the function of intestinal AP and its relation to day-night feeding changes especially in connection with the MSG syndrome., A. Martinková, Ľ. Lenhardt, Š. Mozeš., and Obsahuje bibliografii
As nitric oxide is considered a mediator of liver oxid ative metabolism during sepsis, we studied the effects of exogenous nitric oxide, produced by NO-donor, (±)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR-3), on cell viability, urea biosynthesis and oxygen consumption in rat hepatocyte cultures. Nitric oxide release from NOR-3 was studied using 4,5-diaminofluorescein diacetate. Urea levels were measured by the spectrophotometric method. Cell viability was determined by the MTT test and trypan blue exclusion test, whereas oxygen consumption was measured by a polarographic technique. After 2 h treatment, NOR-3 induced an increase in the levels of nitric oxide. After 2 h of treatment and 24 h after the end of the treatment with NOR-3, both cell viability and urea synthesis were significantly reduced in comparison to the controls for NOR-3 concentrations equal to or greater than 50 μM. A reduction in oxygen consumption was observed in hepatocytes after 40 min treatment with 100 μM NOR-3, even if the cell viability was unchanged. Reduction of oxygen consumption is an early indicator of the metabolic alterations in hepatocytes exposed to nitric oxide. These findings suggest that nitric oxide accumulation acts on hepatocyte cultures inducing cell death and reduction of urea synthesis after 2 hours., R. Chimenti, G. Martino, S. Mazzulla, S. Sesti., and Obsahuje bibliografii a bibliografické odkazy
a_1 In this study, we have determined power output reached at maximal oxygen uptake during incremental cycling exercise (PI,max) performed at low and at high pedaling rates in nineteen untrained men with various myosin heavy chain composition (MyHC) in the vastus lateralis muscle. On separate days, subjects performed two incremental exercise tests until exhaustion at 60 rev . min-1 and at 120 rev . min-1. In the studied group of subjects PI,max reached during cycling at 60 rev . min-1 was significantly higher (p=0.0001) than that at 120 rev . min-1 (287±29 vs. 215±42 W, respectively for 60 and 120 rev . min-1). For further comparisons, two groups of subjects (n=6, each) were selected according to MyHC composition in the vastus lateralis muscle: group H with higher MyHC II content (56.8±2.79 %) and group L with lower MyHC II content in this muscle (28.6±5.8 %). PI,max reached during cycling performed at 60 rev . min-1 in group H was significantly lower than in group L (p=0.03). However, during cycling at 120 rev . min-1, there was no significant difference in PI,max reached by both groups of subjects (p=0.38). Moreover, oxygen uptake (VO2), blood hydrogen ion [H+], plasma lactate [La-] and ammonia [NH3] concentrations determined at the four highest power outputs completed during the incremental cycling performed at 60 as well as 120 rev . min-1, in the group H were significantly higher than in group L. We have concluded that during an incremental exercise performed at low pedaling rates the subjects with lower content of MyHC II in the vastus lateralis muscle possess greater power generating capabilities than the subjects with higher content of MyHC II. Surprisingly, at high pedaling rate, power generating capabilities in the subjects with higher MyHC II content in the vastus lateralis muscle did not differ from those found in the subjects with lower content of MyHC II in this muscle., a_2 We have concluded that during an incremental exercise performed at low pedaling rates the subjects with lower content of MyHC II in the vastus lateralis muscle possess greater power generating capabilities than the subjects with higher content of MyHC II. Surprisingly, at high pedaling rate, power generating capabilities in the subjects with higher MyHC II content in the vastus lateralis muscle did not differ from those found in the subjects with lower content of MyHC II in this muscle, despite higher blood [H+], [La-] and [NH3] concentrations. This indicates that at high pedaling rates the subjects with higher percentage of MyHC II in the vastus lateralis muscle perform relatively better than the subjects with lower percentage of MyHC II in this muscle., J. Majerczak, Z. Szkutnik, K. Duda, M. Komorowska, I. Kolodziejski, J. Karasinski, J. A. Zoladz., and Obsahuje bibliografii a bibliografické odkazy
Alterations of calcium handling and other second messenger cascades including protein kinase C (PKC) and A (PKA) were suggested to be responsible for abnormal vascular function in spontaneously hypertensive rats (SHR). However, the relative contribution of these pathways to vasoconstriction is still not completely understood. We investigated the effect of Ro 31-8220 (PKC inhibitor) and H89 (PKA inhibitor) on vasoconstriction induced by 120 mM KCl or by addition of 10 μM noradrenaline (NA) in isolated femoral arteries of control Wistar rats and SHR. Moreover, we investigated these responses in the presence and absence of Ca2+ ions in the incubation medium in order to assess the role of calcium influx in these contractions. We observed that while the vasoconstriction in the presence of calcium was not different between Wistar and SHR, the difference between constriction elicited by NA addition in the absence and presence of external calcium was larger in SHR. The inhibition of PKC had no effect on constrictions in SHR, but diminished constrictions in Wistar rats. PKA inhibition slightly enhanced constrictions in Wistar rats, but reduced them in the presence of calcium in SHR. We conclude that vasoconstriction elicited by adrenergic stimulation is more dependent on extracellular calcium influx in SHR compared to Wistar rats. Moreover, the activation of PKA contributes to this calcium-dependent vasoconstriction in SHR but not in Wistar. On the other hand, PKC activation seems to play a less important role in vasoconstriction in SHR than in Wistar rats., M. S. Bal ... [et al.]., and Obsahuje seznam literatury
The physiological significance of serotonin released into the intestinal lumen for the regulation of motility is unknown in humans. The aim of this study was to evaluate the effect of serotonin infused into the lumen of the gastric antrum, duodenum or the jejunum, on antro-duodeno-jejunal contractility in healthy human volunteers. Manometric recordings were obtained and the effects of either a standard meal, continuous intravenous infusion of serotonin (20 nmol/kg/min) or intraluminal bolus infusions of graded doses of serotonin (2.5, 25 or 250 nmol) were compared. In addition, platelet-depleted plasma levels of serotonin, blood pressure, heart rate and electrocardiogram were evaluated. All subjects showed similar results. Intravenous serotonin increased migrating motor complex phase III frequency 3-fold and migrating velocity 2-fold. Intraluminal infusion of serotonin did not change contractile activity. Platelet-depleted-plasma levels of serotonin increased 2-fold following both intravenous and high doses of intraluminal infusions of serotonin. All subjects reported minor short-lived adverse effects following intravenous serotonin stimulation, while only half of the subjects reported minor short-lived adverse effects following intraluminal serotonin stimulations. We conclude that exogenous serotonin in the lumen of the upper part of the small intestine does not seem to change antro-duodeno-jejunal contractility significantly in healthy adult volunteers., M. B. Hansen, F. Arif, H. Gregersen, H. Bruusgaard, L. Wallin., and Obsahuje bibliografii a bibliografické odkazy
Many studies documented the relationship between elevated plasma concentrations of natriuretic peptides and cardiovascular diseases, especially heart failure. However, it is still uncertain whether physical exercise leads to a significant release of natriuretic peptide in healthy subjects. The aim of this study was to determine the effect of maximal physical activity on plasma BNP concentrations in healthy individuals within 3 hours after the short-term exercise. BNP plasma concentrations were measured in 15 healthy volunteers before, immediately after as well as 1 hour and 3 hours after bicycle spiroergometry. Maximal workload and exercise capacity were assessed in watts, wattseconds, metabolic equivalents and VO2max. Mean BNP plasma levels before, immediately after, 1 hour and 3 hours postexercise were 19.4±2.5; 30.6±4.7; 17.9±2.5 and 18.7±3.1 pg/ml, respectively. The increase of BNP concentrations immediately after exercise was statistically significant (p=0.0017) compared to baseline values. We did not find any correlation between the post-exercise increase of BNP levels and age, body mass index, maximal workload or exercise capacity. In conclusion, short-term maximal physical exercise in healthy individuals led to a fast and transient rise of plasma BNP concentrations, which remained well within normal range and far below the cut-off value for heart failure (100 pg/ml)., J. Krupička ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Activation of sublobule IX-b of the cerebellar vermis evokes hypotension, bradycardia and decrease of the phrenic nerve activity in the anesthetized animal. Cardiac performance during the isovolumic phases of systole and relaxation can be evaluated by dP/dt max, Vpm, dP/dt/DP40 and τ, respectively. In the present study, we evaluated the changes on cardiac function evoked by the stimulation of sublobule IX-b. New Zealand white rabbits were anesthetized, paralyzed and artificially ventilated. A posterior craniotomy was made to reveal and stimulate the cerebellar uvula (4 s train; 50 Hz; 1 ms; 20 μA). The femoral artery and veins were cannulated and a Swan-Ganz catheter was advanced in the upper abdominal aorta to control afterload when inflating the balloon. The left ventricle was catheterized with a Millar catheter. Blood pressure, heart rate, left ventricular pressure were monitored. Results showed a significant decrease on sublobule IX-b stimulation of all the indices of systolic function and an increase of τ indicating a decrease in the speed of the relaxation. These data provide the first evidence of the influence of sublobule IX-b on cardiac function. They may contribute to the understanding of the origin the cardiovascular changes that were observed in two patients with vermian and paravermian hemorrhage., I. Rochas, V. Gonçalves, M. J. Bettencourt, L. Silva-Carvalho., and Obsahuje bibliografii a bibliografické odkazy
We evaluated the effects of exercise on the vascular constrictor responses to α-adrenergic stimulation in the db/db mice. Twenty male db/db and their age-matched wild-type (WT) mice were exercised (1 hour/day, five days a week). Mice were anesthetized 7 weeks later, thoracic aortae were mounted in wire myograph and constrictor responses to phenylephrine (PE, 1 nM-10 μM) were obtained. Citrate synthase activity measured in the thigh adductor muscle was significantly increased in db/db mice that were exercise trained. Maximal force generated by PE was markedly greater in db/db aortae and exercise did not attenuate this augmented contractile response. Vessels were incubated with inhibitors of nitric oxide synthase (L-NAME, 200 μM), endothelin receptors (bosentan, 10 μM), protein kinase C (PKC) (calphostin C, 5 μM), cyclooxygenase (indomethacin, 10 μM) or Rho-kinase (Y-27632, 0.1 μM). Only calphostin-C normalized the augmented PE-induced constriction in db/db and db/db- exercised mice to that observed in WT (p<0.05). Cumulative additions of indolactam, a PKC activator, induced significantly greater constrictor responses in aortic rings of db/db mice compared to WT and exercise did not affect this response. Our data suggest that the augmented vasoconstriction observed in the aorta of db/db mice is likely due to increased PKC activity and that exercise do not ameliorate this increased PKC-mediated vasoconstriction., M. Khazaei, F. Moien-Afshari, T. J. Kieffer, I. Laher., and Obsahuje bibliografii a bibliiografické odkazy
Several diseases induce hypermetabolism, which is characterized by increases in rest ing energy expenditures (REE) and whole body protein loss. Exaggerated protein degradation is thought to be the driving force underlying this response. The effects of caspase and calpain inhibitors on REE in physiological and hypermetabolic conditions, how ever, are unknown. Thus, we studied whether MDL28170 (calpain inhibitor) or z-VAD-fmk (caspase inhibitor) affect REE under physiological conditions and during hypermetabolism post -burn. Rats were treated five times weekly and observed for 6 weeks. Treatmen t was started 2 h (early) or 48 h ( late) after burn. In normal rats, MDL28170 transiently increased REE to 130 % of normal during week 2-4. z-VAD-fmk reduced REE by 20-25 % throughout the observation period. Within 14 days after burns, REE increased to 13 0±5 % . Whereas MDL28170/ early treatment did not affect REE, MDL28170/ late transiently increased REE to 180±10 % of normal by week 4 post- burn. In contrast, with z -VAD -fmk/ early REE remained between 90-110 % of normal post- burn. z-VAD-fmk/ late did not affect burn-induced increases in REE. These data suggest that caspase cascades contribute to the development of hypermetabolism and that burn-induced hypermetabolism can be pharmacologically modulated. Our data point towards caspase cascades as po ssible therapeutic targets to attenuate hypermetabolism after burns, and possibly in other catabolic disease processes., P. G. Vana, H. M. LaPorte, R. H. Kennedy, R. L. Gamelli, M. Majetschak., and Obsahuje bibliografii