Acta physiologica et pharmacologica Bulgarica (Acta Physiol Pharmacol Bulg)

Publisher: Bŭlgarska akademii︠a︡ na naukite

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Other titles Acta physiologica et pharmacologica Bulgarica
ISSN 0323-9950
OCLC 1277079
Material type Periodical
Document type Journal / Magazine / Newspaper

Publications in this journal

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    ABSTRACT: The age-related differences in the synapses of the paraventricular hypothalamic nucleus (PVN) were studied with transmission electron microscopy in young (3-month-old) and senescent (25-month-old) Wistar rats. The changes in the axodendritic (ADS) and axospinous (ASS) synapses in the PVN neuropil were determined by morphometry. The majority of synapses were of the ADS type. In senescent rats the density of both ADS and ASS was diminished. The mean area of the ASS presynaptic boutons in aged rats was more enlarged than of the boutons in the ADS. The parameters characterising synaptic vesicles (SV) were diminished in aging rats. The number of SV per synaptic bouton decline was not significantly different. The changes in the length of synaptic contact zone (SCZ) were not significant with the exception of the total SCZ length per 1000 microm2 and the total area of the SCZ per 1000 microm3 in the ADS. The decrease of the number of dendritic spines (DS) per 1000 microm2 in the neuropil was significantly age-related diminished. Moreover, the mean area of the DS was significantly enlarged.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):75-82.
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    ABSTRACT: We intended to study the effect of swimming exercise on the brain, liver and heart malondialdehyde (MDA) levels which are the last product of oxidation, and to compare them with the brain, liver and heart MDA levels of controls. The experiments were carried out on 20 Wistar rats which were fed with a standard laboratory chow diet ad libitum. Rats were distributed in two groups, control group (n = 10) and exercise group (n = 10). The exercise group rats were exposed to swimming exercise for 30 minutes. After this animals in each group were sacrificed by decapitation, their brain, liver and heart tissues were quickly removed. MDA levels of the brain, liver and heart were determined according to the method in which MDA reacts with thiobarbituric acid. Results were evaluated by the Mann-Whitney U test. The liver and heart MDA levels in the exercise group were (29.59+/-6.73 and 10.49+/-1.90 nmol/g tissue, respectively) significantly higher than in the control group (21.78+/-3.46 and 8.86+/-1.25 nmol/g tissue, p<0.01 and p<0.05, respectively). However, the brain MDA levels were similar in both groups (exercise group 19.37+/-5.50 nmol/g tissue and control group 16.58+/-2.44 nmol/g tissue; p=0.325). It is concluded that swimming exercise might cause oxidative stress.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):43-5.
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    ABSTRACT: Oxygen uptake efficiency slope (OUES) is an index meant to provide an objective measure of cardiopulmonary function at submaximal exercise. The aim was to study the exercise performance and OUES in obese children performing standardized exercise. Sixty children aged 6-17 years performed incremental treadmill exercise test. They were divided into two groups matched by age, sex and height: thirty obese subjects (15 girls/15 boys; BMI = 27.4+/-1.7 m x kg(-2)) and 30 controls (BMI = 18.8+/-1.0 m x kg(-2)). Perceived exertion was assessed by means of CR-10 Borg scale. The duration of the exercise for the obese children was significantly shorter than for controls (p = 0.010) but obese children had greater absolute values for oxygen uptake (VO2 peak mL x min(-1) = 1907+/-249 vs. 1495+/-208; p = 0.013) which, adjusted for body mass, decreased significantly (VO2/kg mL x min(-1) x kg(-1) = 29.2+/-1.4 vs. 33.6+/-1.3; p < 0.001). OUES correlated strongly with VO2 peak (r = 0.91) and oxygen pulse (r = 0.80), as well as with anthropometric variables height (r = 0.88) and age (r = 0.83). Extremely high correlation was found between OUES calculated for 100% of exercise duration and OUES at the anaerobic threshold (r = 0.979; p < 0.001). No significant differences were found between the studied groups concerning the absolute values of OUES. Obese children rated perceived exertion significantly higher than controls (Borg score 6.2+/-0.4 vs. 5.2+/-0.4; p = 0.001). In conclusion, the absolute metabolic cost of exercise and perceived exertion were higher in the obesity group. OUES is an objective measure of cardiopulmonary reserve that doesn't require a maximal effort but it is considerably dependent on anthropometric variables which impedes its interpretation as exercise index in childhood.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):59-64.
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    ABSTRACT: Angiotensin II (ANG II) significantly increased noradrenaline (NA) uptake by cortical, hypothalamic and hippocampal synaptosomes thus activating noradrenergic neurotransmission. ANG II did not affect NA uptake by striatal synaptosomes. The interaction between AT1 receptors and noradrenergic neurons and the involvement of brain noradrenergic neurotransmitter system in ANG II-induced drinking in rats is suggested by the increase of NA uptake in hypothalamus and frontal cortex which are rich in AT1 receptors and are of importance for drinking behavior. The ANG II-receptor antagonists losartan, EXP 3174, sarmesin and saralasin decreased NA uptake in all brain regions studied as compared to the uptake in the same brain regions of ANG II-injected animals thus antagonising the effect of ANG II. There is no relationship between the inhibition of ANG II-induced water intake and the changes of NA uptake under the effect of the ANG II-receptor antagonists.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):65-8.
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    ABSTRACT: An inverse relationship between HDL-c plasmatic levels and Li+ flux (Na+-Li+ exchange mediated) has been reported in normotensive individuals with hypertensive ancestors as well as in essential hypertensive subjects. This lipoprotein reaction with plasmatic membrane components induces modifications in membrane transport mechanisms as well as in cellular enzymes. In this paper we present data on Li+ flux (Na+-Li+ exchange mediated) in red blood cells from normotensive individuals without hypertensive ancestors. Kinetic analysis of Li+ efflux as a function of Na+(extracell) concentration was carried out. Vmax and Km values were determined. HDL-c plasmatic levels were also determined. Vmax showed a significant inverse correlation with HDL-c levels. No significant correlation of Km values with HDL-c levels was observed. The data presented support previous data showing that variable Vmax is sensitive to cellular environmental factors. Otherwise the Km variable not influenced by these factors is sensitive to hereditary influences.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):39-42.
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    ABSTRACT: The OLETF rat develops microangiopathic complications similar to human diabetes and is considered a useful model of Type 2 DM. Erythrocyte, platelet and leucocyte abnormalities described in diabetic patients are thought to play a role in the development of diabetic microangiopathy. This study was designed to investigate whether OLETF rats show hematological alterations and the effect of sucrose treatment on metabolic and blood parameters. Hematological parameters, body weight, food and water intake, fasting and non-fasting blood glucose (BG) and HbA1c were measured in OLETF rats treated for two months with 30% sucrose added to drinking water. Non-treated OLETF rats and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats were used as controls. In the control OLETF rats the number of platelets (Plt) and red blood cells (RBC) was higher, while the mean cell volume (MCV) and the mean cell hemoglobin content (MCH) were lower compared with LETO. Mean cell hemoglobin concentration (MCHC) was significantly higher in the diabetic rats. Sucrose administration decreased food intake and body weight and increased fasting blood glucose and HbA1c. It resulted in a decrease of RBC, Hb, Hct, MCV and MCH compared with control OLETF, while Plt count increased significantly. Our results point to significant alterations in erythrocyte count and morphology and Plt count in diabetic OLETF rats compared with non-diabetic LETO. Sucrose administration accelerated the development of diabetes, affected blood cells inducing the suppression of RBC and an increase in Plt count and some of its effects persisted after sucrose withdrawal.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):69-74.
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    ABSTRACT: This paper deals with the effects of high (microwave) and extremely high (millimetre waves, MMW) frequency electromagnetic fields on the membrane processes and ion channels, molecular complexes, excitable and other structures. Microwaves as well as millimetre waves are widely used in medical practice and in everyday life. The existence of interaction between the exogenous and endogenous electromagnetic fields with biological systems is now a subject of intense discussion. The most contentious question is the existence of a possible specific (non-thermal) effect of microwaves, unrelated to that caused by increased temperature. Although numerous data have been published on the possible non-thermal effects of the studied electromagnetic fields on different kinds of living systems, only little understanding is gained about the modes of microwave action. Here we review data, which provide evidence that non-thermal microwave effects do exist and may play a significant role. This evidence is based on research at all biological levels, from cell-free systems through cells, tissues and organs, to animal and human organisms.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):89-100.
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    ABSTRACT: The aim of the present work was to study the antioxidant activity of the new derivative of succinic acid-succinate mono[(2-dimethyl-amino) ethyl ether] of succinic acid (yackton) under conditions of hypoxic and hemic hypoxia as well as to examine in vitro the antiradical activity of this preparation. Hypoxia in the rats was modelled by: (i) allowing the rats to breath a gas mixture with 7% O2 and 93% N2 for 30 minutes (hypoxic hypoxia), and (ii) injecting the rats sodium nitrite subcutaneously in a dose of 60 mg/kg body weight (hemic hypoxia). Yackton was injected intraperitoneally to both groups 30 minutes before the extreme influence in a dose of 140 mg/kg body weight. Then in homogenates and in post-mitochondrial fractions of liver, heart, lungs, brain we studied the content of secondary products of lipid peroxidation (LPO), activity of antioxidant enzymes superoxide dismutase (SOD) and catalase, and the activity of enzymes responsible for the maintenance of reduced glutathione (GSH) glutathione reductase (GR-ase) and glutathione peroxidase (GP-ase). In vitro studies were made on the antiradical activity of yackton in reaction with the stable radical diphenylpicrylhydrazine (DPPH) as well as on the reaction velocity of the preparation with DPPH, and its period of semi-transformation in a non-radical form. It was shown that yackton treatment before hypoxic and hemic hypoxia decreased lipid peroxidation (LPO) level and increased SOD activity. After the yackton injection the state of glutathione system was normalized in comparison with its state at hypoxic and hemic hypoxia. Yackton had no antiradical properties in vitro. We concluded that yackton promotes optimization of prooxidant-antioxidant homeostasis of the organism under the hemic and hypoxic hypoxia acting as antioxidant of a non-direct action.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):53-8.
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    ABSTRACT: The aim of this study was to compare classical Balke and Bruce protocols with our modification of Balke protocol in pediatric cardiorespiratory diagnostics. The modification of Balke consists of nine stages per 1 min at a constant velocity of 5.6 km x h(-1) and increasing elevation from 6% to 22% in 2% increments. Sixty healthy children (mean age = 13.3+/-0.2 years; BMI = 18.8+/-0.6 kg x m(-2); mean +/- 95% CI), divided into three groups of 20 children each, matched by age, height and BMI performed integrative cardiopulmonary exercise testing using one of the treadmill protocols mentioned. At the end of each exercise increment and throughout the recovery period the children were asked to rate the perceived exertion (RPE) using the Borg Category Ratio scale--CR-10. Exercise results showed that Balke protocol had the longest duration (21.7+/-0.6 min.) and the lowest values for VO2/kg (34.2+/-1.8 ml x min(-1) x kg(-1)) due to the minimal workload increments. Bruce protocol had intermediate duration (14.9+/-1.1 min.) and children achieved the highest VO2/kg (48.6+/-2.7 ml x min(-1) x kg(-1)) but the test is symptom-limited which is ethically unacceptable in childhood. Exercise data revealed that our modification of the classical Balke protocol had an optimal duration (11 min.) and yielded peak VO2/kg values (39.4+/-2.3 ml x min(-1) x kg(-1)) adequate for evaluation of children's exercise capacity. Children's ratings of perceived exertion were highest in Bruce protocol (6.5+/-0.4) and lowest in the original Balke protocol (4.5+/-0.8). In conclusion, the modification of Balke protocol is suitable and reliable for screening and clinical testing in pediatric age group.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):47-51.
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    ABSTRACT: Cholecystokinin (CCK) is a classical brain-gut peptide that exerts a variety of physiological actions in the gastrointestinal tract and central nervous system. CCK occurs in several molecular forms of varying aminoacid length, the sulphated octapeptide (CCK-8) being the predominant form in the brain. CCK mediates its effects through interaction with specific receptors subdivided in two subtypes--CCK-A (present in the periphery and in few selected brain nuclei) and CCK-B (the predominant receptor subtype in the brain). CCK is implicated in variety of behavioral functions as satiety, anxiety, exploratory and locomotor activity and learning and memory. After a brief description of the distribution, molecular forms, release, inactivation, etc. of CCK in the brain, the present review summarizes the recent data on the role of CCK in learning and memory. The memory-enhancing effects of CCK have been demonstrated in various types of memory. Data showing that CCK-A receptors mediate mnemonic while CCK-B receptors mediate amnestic effects are also presented.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):83-8.
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    ABSTRACT: Natural sulfated polysaccharides (SPs) derived from brown seaweed comprise a complex group of macromolecules with a wide range of important physiological properties. SPs have been shown to bind and directly regulate the bioactivity of growth factors and cytokines such as basic fibroblast growth factor, interferon, various enzymes and transforming growth factor. Myostatin is a member of the transforming growth factor-beta (TGF-beta) family that acts as a negative regulator of skeletal muscle mass. In this work we demonstrated that SPs isolated from the brown seaweed Cystoseira canariensis bind to the myostatin protein in serum.
    Acta physiologica et pharmacologica Bulgarica 01/2003; 27(2-3):101-6.
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    ABSTRACT: The paper deals with an original approach of reconstructing the muscular force profile, in voluntary exercise of human subjects. Based on the idea that the changes within the activation of the muscle are the most relevant factors in producing the muscular force, we built a dynamic estimator of the force within the isometric dynamic tasks (ACTM), using the surface EMG as an input signal. The exercise involved mainly the Biceps and Brachioradialis muscles, together. The estimated resultant force was built taking into consideration the weighted contribution of the acting muscles. The weights were taken as to match the actual force measured at the wrist within a steady contraction, then used accordingly, during the dynamic exercise. The results show a spectacular improvement over previous attempts. This may open a practical way towards the estimation of the resultant force at the joints.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):45-8.
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    ABSTRACT: The study was undertaken to analyze the cognitive determinants of event-related potentials (ERPs) under two stimulus paradigm discrimination conditions. We were interested in how the processes of anticipation and preparation for motor action are associated with the ERPs and what is the interrelation between them. Subjects were presented in randomized order three pairs of tones: warning (S1) and imperative (S2) one with different information content. Two ERPs types were studied: (1) The acoustic evoked potentials elicited by warning and imperative stimulus. (2) The early-initial (iCNV) and late-terminal (tCNV) contingent negative variation. Our data suggested that the processing of S2 depends not only on its physical characteristics and information content but also on the prestimulus brain activity reflecting expectancy or motor preparation. The higher iCNV amplitude contralaterally to the movement side under the condition requiring motor action compared to the paradigms without movement preparation could be associated also with the response related processes.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):107-10.
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    ABSTRACT: To determine A-waves of a family with autosomal recessive form of demyelinatig hereditary motor and sensory neuropathy Lom (HMSNL). A-waves were investigated during conventional F-wave study of family members with HMSNL which had genetic testing. During routine F-wave studies A-waves were observed in all tested nerves. They appeared between M-responses and F-wave. The A-waves were with low amplitude, shorter duration and constant shape and latency than F-waves. They appeared independently of F-waves. A-waves were more often recorded as multiple waves in lower and upper extremities. More than three A-waves per nerve were found mostly in ulnar and facial nerves. In 16 cases A-waves were found in the absence of F-waves. It is assumed that the A-waves could be seen as additional signs of pathology because they were not observed in unaffected members of the family and in healthy subjects.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):55-8.
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    ABSTRACT: Analysis of motor unit (MU) activity gives an insight to relationships between physiologically activated human motoneurons (MNs). It was assumed that the investigation of recurrent inhibition under these conditions might advance our understanding of the role it plays in motor control. To allow for proper interpretation of experimental results, a series of computer simulations modeling different interactions between MNs was performed. For analysis, several modifications of crosscorrelation technique were applied. These functions complement each other and help to decide about the character of the interaction. The results show that with the same IPSP parameters, inhibition is more pronounced when the firing rate of the target MN is lower. Even IPSP of the amplitude as low as 0.05 mV has characteristic effects on all the functions applied in this study. If the effect is present only on one function, it is certainly an artifact.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):79-82.
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    ABSTRACT: The present study compared the learning of sensorimotor transformation rules in young and elderly subjects. In a first experimental session, participants executed manual tracking movements first under normal, and then under left-right reversed visual feedback. Overall, seniors' tracking performance was lower. However, both age groups responded in a quantitatively similar way to the feedback change: Tracking errors increased by a similar amount at the onset of left-right reversal, and then gradually returned to the respective baseline levels. In a second session, visual up-down reversal was added to the left-right reversal. The initial increase of tracking error was substantially smaller than in the first session, and this benefit was even more pronounced in seniors. We interpret the benefit of the second session as learning-to-learn, i.e., as enhancement of a general ability to learn new skills, and conclude that in our study, learning-to-learn was more pronounced in elderly subjects.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):89-92.
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    ABSTRACT: The study aims to clarify the effect of exposure to microwave electromagnetic field (MMW) on muscle fibre fatigue. Repetitive stimulation with interstimulus interval of 200 ms was applied on isolated frog muscle fibre to evoke intracellular action potentials and twitch contractions. After their recording muscle fibre preparation was moved in a Petri dish with radius of 28 mm on open air for one hour exposure to continuous MMW with frequency of 2.45 GHz and power density of 20 mW/cm2. Then it was again moved in the chamber with non irradiated Ringer's solution at controlled temperature for the repeated records. After MMW exposure the changes in amplitude and time parameters characterizing fatigue were attenuated and delayed vs. controls. The twitch amplitude curve described an drastic fall in the first 5 sec followed by an increase and next decrease. MMW (2.45 GHz) have a specific, non-thermal influence on muscle fibre activity resulting in some resistance to fatigue.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):37-40.
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    ABSTRACT: In the present study motor unit (MU) firing pattern was analysed during long-term static contraction in order to see if fatigue would induce rotation of activity between different MU. Surface as well as intramuscular EMG were obtained from ten subjects during a sustained hand lift for 5 minutes after performance of a 30% MVC fatiguing contraction of the extensor carpi radialis muscle. A newly developed decomposition program constituted a powerful tool to obtain detailed knowledge of long term activity pattern of MU during low force contractions. Although the muscle was highly fatigued the majority of MU showed a continuous firing pattern after recruitment and no clear incidences of rotation were found for any of the subjects. Therefore, long term, low force contractions, as performed during many occupational work tasks, may involve continuous activation of the low threshold MU and this could have mechanical as well as metabolic implications for these muscle fibers.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):73-8.
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    ABSTRACT: The excitability changes of human axons during 100-ms recovery cycles are investigated by paired stimulations. Using double cable models of normal axons and of three simulated types amyotrophic lateral sclerosis (termed as ALS1, ALS2 and ALS3, respectively), the recovery cycles are presented in the case of action potential propagation and in the case of a uniformly polarized fibre. Following the testing pulse, human axons go through an oscillating sequence of excitability changes, the recovery cycle: they are initially inexcitable (absolute refractory period), than excitable with a raised threshold (early subnormal period) and after about 2-ms they become more excitable than normal (superexcitable period). For uniformly polarized axons in the normal and ALS1 types, the superexcitable period usually followed by a late subnormal period. With increasing the degree of ALS, the length-dependent potentials propagate with complex, desynchronized amplitudes and velocities, and abnormalities in the recovery cycles are obtained for the ALS3 axonal types.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):41-4.