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: 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 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: 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: 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: 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: 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: 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: 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: 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: 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: Coordination of voluntary discrete motor responses with ongoing background activity like tremor is investigated for the single-muscle multiple-task condition by experimental and theoretical work. It is shown that the periodic background activity entrains the discrete responses. The experimental results are described by a model of the motor execution stage, and several possible consequences of the model for the motor behavior in Parkinsonian tremor patients are discussed.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):127-30.
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    ABSTRACT: The study is an attempt to reveal the EEG frequency dynamic changes over sites covering areas reflecting the cognitive processes during movement imagery. Subjects were instructed to imagine a self-paced movement after listening to randomized sentences differing in lack of object or instrument of action. EEG was recorded over frontal, sensorimotor and temporo-parietal areas in both hemispheres. Frequency dynamics was estimated using power spectra (PS), band-pass filtering and bispectra. Two types of frequency dynamics were established: (A) a linear one, up to 24 Hz, with most pronounced oscillations in 12-14 Hz and in 16-22 Hz, synchronized first in frontal and precentral areas; (B) a nonlinear one between 24 and 63 Hz, with fractal structure and self-similarity, characterized by fractal dimension of 1.7-1.9. The narrow band of 23-26 Hz in the boundary between linear and nonlinear regimes expressed obvious synchronization and time re-distribution of oscillations among sites and sentence-types.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):115-8.
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    ABSTRACT: The contribution of nociceptive Adelta-fibres and C-fibres of the central pad of the foot to nociceptive spinal flexor reflex pathways (FRA-type) and to nociceptive excitatory reflex pathways to foot extensors (non-FRA type) was investigated in high spinal cats by blocking A-fibres completely by TTX; effects persisting after TTX were attributed to nociceptive C-fibres. The results revealed that both Adelta- and C-fibre afferents contributed to nociceptive reflexes of an FRA pattern and of a non-FRA pattern, the effects of Adelta-fibres being evoked with a distinctly shorter delay than those of C-fibres. Partly Adelta-fibres exerted a significant inhibitory influence on the C-fibre action in FRA pathways. A distinct part of the opioid action on nociceptive reflex pathways of the FRA-type and of the non-FRA-type was evidently exerted via C-fibres.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(3):193-6.
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    ABSTRACT: A method for simulating the effect of electrodes of any shape on surface detected motor unit action potentials (MUAPs) is described. The method is based on an approach we have recently proposed according to which the spatial integration of an electrode with physical dimensions is described as a two-dimensional spatial filtering of the electric potential over the skin. The effect of circular, square and bar electrodes on the frequency characteristics of surface detected MUAPs is investigated from the theoretical point of view. In particular the appearance of characteristic frequencies at which the power spectrum of the detected surface EMG signal is zero (spectral dips) is analyzed in relationship with electrode size and shape. It is shown that the physical dimensions of the electrodes may determine spectral dips in the surface EMG power spectrum but only for particular electrode shapes. Simulation results are shown to validate the theoretical considerations.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):63-6.
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    ABSTRACT: The majority of studies devoted to reveal electrophysiological correlates of words and sentences comprehension, imageability and remembering are based on the event-related potentials and frequency synchronization in different narrow frequency bands. These linear methods reveal some patterns of EEG activity in time and frequency domain. Having in mind that the activation of many cortical structures is a result of mass of nonlinearly interconnected neurons, the linear methods seem to be insufficient to discover the complexity of the information transfer. We revealed recently nonlinear dynamic transients in EEG, long before real performance of goal-directed voluntary movements with different temporal and spatial distributions over frontal, sensorimotor and parietal cortical areas (Popivanov and Dushanova, 1999). The aim of this study was to establish whether similar behavior of the nonlinear characteristics exists when the subject imagines movements of a given type. The Kolmogorov entropy computed over time after the sentence end proved to be an useful characteristic that complement the linear methods.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):119-22.
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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: We studied the influence of stance width and vision on the plantar pressures for the left and right foot during bipedal quiet standing on the pressure-sensitive insoles. The support widening shifted the left and right centers-of-foot-pressure (CFPs) laterally and forward (right foot), diminished SDs of: the left and right mean plantar pressures (MPPs), the anteroposterior and mediolateral displacements of left and right CFPs. It also decreased negative correlations between left and right MPPs and between mediolateral displacements of left and right CFP and increased positive correlation between anteroposterior displacements of left and right CFPs, more expressive with eyes-open. The later results suggested that support widening increased the weight of exploratory behaviour regarding anteroposterior equilibrium and decreased exploratory sway serving mediolateral equilibrium. Eyes' closure lead to a small left bias of the body-weight-bearing and forward shift of the left versus right CFP, thus suggesting that vision increased bilateral symmetry of stance.
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(3):137-42.
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    ABSTRACT: We studied the periodicity of a relatively slow oscillation of the muscle activation, via the surface electromyogram (EMG), recorded from the Biceps and Brachioradialis muscles, under an endurance isometric task. The peaks in the Root Mean Square (RMS) of the EMG were assigned as peaks of the muscle activation; the estimate of their periodicity was checked via correlation. 32 subjects participated in different exercises involving isometric isotonic tasks, at 25%, 50% and 75% MVC (maximal voluntary contraction). The activation of the muscle under such an exercise has an overall low frequency periodicity of between 14.29 s and 16.75 s with standard deviations (sd) between 2.97 s and 5.04 s, independent of the intensity of the task and sex. They are larger for the Brachioradialis (mean 15.08-19.6 s/sd 2.59-6.3 s) than for the Biceps (mean 11.96-16.41 s/sd 1.24-4.86 s).
    Acta physiologica et pharmacologica Bulgarica 02/2001; 26(1-2):49-52.