Kainic acid, the analog of excitatory amino acid L-glutamate, interacts with specific receptors in the central nervous system. During last 25 years it has become a tool for studying many human brain disorders, for example human temporal lobe epilepsy, Huntington's chorea etc. Systemic administration of kainic acid results in neuronal death in experimental animals. The mechanism, by which kainic acid produces neuronal damage is still unclear, as well as physiological function of kainate receptors remain to be elucidate. This review attempts to survey the major achievements reached in the studies, which were publicized throw the last three decades.
- MeSH
- agonisté excitačních aminokyselin farmakologie MeSH
- degenerace nervu chemicky indukované MeSH
- kyselina kainová farmakologie MeSH
- lidé MeSH
- mozek účinky léků patofyziologie MeSH
- receptory kyseliny kainové fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- agonisté excitačních aminokyselin MeSH
- kyselina kainová MeSH
- receptory kyseliny kainové MeSH
With his experiments and findings J. Ev. Purkyne influenced 34 scientific disciplines; in some of them he is assumed to be their founder (embryophysiology, histology, pharmacological physiology, biophysics, comparative physiology). He was the pioneer in the field of neuroscience not only due to his neuroanatomical descriptions but namely due to his neurophysiological experiments. Beside the description of "Purkyne cells" and cells of other regions of the brain, Purkyne studied also the structure of neuronal processes and it is possible to attribute him the first description of dendrites. Existing material shows that Purkyne studied also the structure of hippocampus. Those and other papers prove that Purkyne recognised possible functional differences between various types of neurons and he speculated about their mutual relations. Only contemporary particularly detailed knowledge on the structure of hippocampal neuronal circuits, description of the mediator interaction and modulation together with the identification of neuroplastic processes in the hippocampus enable to accomplish the Purkyne's attempt to correlate the structure and function.
- MeSH
- dějiny 19. století MeSH
- neurony cytologie fyziologie MeSH
- neurovědy dějiny MeSH
- Check Tag
- dějiny 19. století MeSH
- Publikační typ
- anglický abstrakt MeSH
- biografie MeSH
- časopisecké články MeSH
- historické články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Československo MeSH
- O autorovi
- Purkinje, J Ev
Function of the central nervous system is based on mutual relations among the nerve cells. Description of nerve cells and their processes, including their contacts was enabled by improvement of optical features of the microscope and by the development of impregnation techniques. It is associated with the name of Antoni van Leeuwenhoek (1632-1723), J. Ev. Purkyne (1787-1869), Camillo Golgi (1843-1926), and Ramón y Cajal (1852-1934). Principal units of the neuronal network are the synapses. The term synapse was introduced into neurophysiology by Charles Scott Sherrington (1857-1952). Majority of the interactions between nerve cells is mediated by neurotransmitters acting at the receptors of the postsynaptic membrane or at the autoreceptors of the presynaptic part of the synapse. Attachment of the vesicles to the presynaptic membrane and the release of the neurotransmitter into the synaptic cleft depend on the intracellular calcium concentration and on the presence of several proteins in the presynaptic element.
- MeSH
- lidé MeSH
- nervová síť fyziologie MeSH
- neurotransmiterové látky MeSH
- synapse fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- neurotransmiterové látky MeSH
BACKGROUND: QT interval dispersion (QTd) is conventionally interpreted as a result of repolarization heterogeneity in ventricular myocardium. However, another concept of QTd origin has been discussed recently, suggesting that different projections of the repolarization vector into individual ECG leads could be responsible for the differences in QT interval duration. Moreover, the reproducibility could be influenced by factors both electrocardiographic (T wave amplitude, U wave) and extracardiac (noise, ECG measures). In the presented study we have followed the QTd in two groups of patients with proved changes of an electric heart field. METHODS AND RESULTS: Studied groups: 1. Control group, 2. Healthy pregnant women, 3. Patients treated with dosulepine. QT interval was measured from 80 unipolar chest leads used for body surface potential mapping. The QTd was significantly higher in both experimental groups in comparison with the control group (p < 0.001). Significant correlation was found between the QTd and dosulepine plasma level (p < 0.001). Also amplitude of the T wave loop was in both groups decreased and its width increased (both p < 0.001). CONCLUSIONS: If appropriate procedure of measurement is used, the QTd is significantly increased in many physiological and pathological states. Clinical relevancy of borderline increased values has to be interpreted very carefully.
- MeSH
- antidepresiva tricyklická farmakologie MeSH
- dospělí MeSH
- dothiepin farmakologie MeSH
- elektrokardiografie * účinky léků MeSH
- kardiovaskulární komplikace v těhotenství diagnóza MeSH
- lidé MeSH
- mapování potenciálů tělesného povrchu MeSH
- srdeční arytmie diagnóza MeSH
- těhotenství MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Názvy látek
- antidepresiva tricyklická MeSH
- dothiepin MeSH
BACKGROUND: In concurrence of our recent findings of the elevation of QT dispersion (QTd) in the group of pregnant women, mathematical approaches were developed aimed to give possible geometrical explanation whether the observed changes result from the rotation or from the changed position of the heart. METHODS AND RESULTS: Mathematical model of the cardiac electrical field approximated as a time variable dipole in a homogenous spatial conductor was developed. From the experimental vectocardiographic records, representing time course of the cardiac dipole, body surface potential maps were calculated on the basis of the model. To validate the adequacy of the model, the reconstructed electrocardiograms were compared with the empiric data. To determine the effects of rotation, original empiric VCG data of the control group were transformed accordingly the hypothetic pregnancy related changes. Calculated surface electrocardiograms were then compared with empiric cardiograms of the pregnant women. CONCLUSIONS: Based on the results, several conclusions can be drawn: 1) QT dispersion is associated also with the geometrical relations between the direction of cardiac vector during the terminal phase of repolarization and the direction of axes in the given system of leads. The dispersion then has its typical occurrence at the thoracic surface--minimums of the QT duration are found in the plane perpendicular to the axis of the terminal vector lead. 2) When the duration of repolarization is estimated from the classic thoracic leads within the phisiological variations of terminal-depolarization vector orientations, can exist that in some cases the minimum of QT interval is and in others it is not recorded by the lead system. Value of QT dispersion between these two extremes will be significantly different. 3) In case of the horizontal declination of the heart, the ECG signal in most of the leads of the body surface mapping has a higher voltage than in case of vertical declination due to a smaller angle between axes of the terminal vector and most of the leads. Such fact will contribute to more accurate reading of the T wave end and to the estimation of QT interval, usually with smaller value of QTd. 4) The change of the cardiac electrical field corresponding to the changed position of the heart (rotation) does not result by itself in QTd changes, if it is evaluated from the records from the whole thorax. Obversely, horizontalization of the heart contributes more to the evaluation of lower QTd values, as it is given above. 5) More then the result of geometrical changes, QT dispersion found in the group women in high level of pregnancy is an effect of changes in the T loop morphology, which was observed in this group. Another possible explanation of the observed dispersion is the non-dipolar character of the electrical field changes during pregnancy.
- MeSH
- dospělí MeSH
- elektrokardiografie * MeSH
- lidé MeSH
- mapování potenciálů tělesného povrchu MeSH
- modely kardiovaskulární * MeSH
- srdce fyziologie MeSH
- srdeční arytmie patofyziologie MeSH
- těhotenství MeSH
- vektorkardiografie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
OBJECTIVE: The effect of various degrees of hypobaric hypoxia and consequent hypothermia on lactate dehydrogenase (E.C.1.1.1.27) activity in blood serum and brain cortex in 14 day-old rats was investigated. DESIGN: Experimental study. SETTING: Institute of Physiology, 1st Med. Faculty, Charles University, Prague. METHODS: 14 day-old rats (Wistar of our own breed) were exposed to mild hypobaric hypoxia (corresponding to altitude of 7000 m, pO2 = 8.6 kPa, BP = 41.2 kPa, lasting 20 min) or strong hypobaric hypoxia (corresponding to altitude of 9000 m, pO2 = 6.4 kPa, BP = 30.7 kPa, lasting 30 min). Just after hypoxic stress the animals were killed by decapitation and on cooled block the grey cortical matter was removed. Blood serum samples as well as brain cortex homogenates were immediately incubated in three variously tempered media (38 degrees Celsius = control values, 30 degrees Celsius and 22 degrees Celsius = hypothermic conditions). The incubation was over (30 min.), and the lactate dehydrogenase (LDH) activity was followed using the Lachema test. RESULTS: The LDH activity was influenced by mild hypobaric hypoxia (7000 m) neither in blood serum nor in brain cortex. Also the values of LDH activities registered in normo or in hypothermic conditions were not different as compared with control values. The strong hypoxia (9000 m) evokes in brain cortex homogenates simultaneously with normothermia and posthypoxic hypothermia (30 degrees Celsius) significant increase of LDH activity. In blood serum the strong hypoxia increased the LDH activity; in subsequent hypothermic condition (22 degrees Celsius) the LDH activity was more lowered. CONCLUSION: The LDH activity in brain cortex as well as in blood serum of young rats (Wistar) seems to be resistent to mild hypoxia (7000 m) as well to hypothermic conditions. The strong hypoxia (9000 m) evokes quite different responses: in brain cortex the LDH activities in hypothermic conditions are higher, in blood serum lower as compared with control values (14 day-old rats stressed by hypoxia only). In control measurements the lowering temperature decreases the mentioned enzyme activity in brain cortex; in blood serum no significant differences could be found.
- MeSH
- krysa rodu Rattus MeSH
- L-laktátdehydrogenasa krev metabolismus MeSH
- mozková hypoxie enzymologie MeSH
- mozková kůra enzymologie MeSH
- nízká teplota * MeSH
- novorozená zvířata MeSH
- potkani Wistar MeSH
- techniky in vitro MeSH
- tlak vzduchu MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- L-laktátdehydrogenasa MeSH
OBJECTIVE: In the following study, possible protective effect of hypothermia (of various degree) on brain cortex metabolic activity in very young animals and adult rats was examined. DESIGN: Experimental study. SETTING: Institute of Physiology, 1st Med. Faculty, Charles University, Prague, Czech Republic. METHODS: Homogenates of brain cortex of 14-day-old and adult rats and simultaneously blood serum were examined for lactate-dehydrogenase activity (LDH), [E.C. 1.1.1.27]. Three variously tempered incubation media (38 degrees C = control values, 30 degrees C = mild hypothermia, 22 degrees C = strong hypothermia) were checked. Also the adult rats (90-120 days) were examined (in the same arrangement). RESULTS: The LDH activity in the blood serum of 14-day-old rats under hypothermic condition was unchanged as compared with control values. In their brain cortex the hypothermia evokes a significant changes in LDH activity (mukat/l). In adult rats the results are different: no significant changes in LDH activity in the brain cortex under hypothermic condition were found, but significant drop in mentioned enzyme activity in the blood serum was established. Finally: in young animals the starting LDH activity in the blood serum as well as in the brain cortex was always significantly higher as compared with values found in adult animals. CONCLUSION: The starting higher LDH activity in the blood serum as well as in the brain cortex in young rats (as compared with adults) and the different feature of LDH changes under hypothermic conditions are considered and discussed especially with the possibility of protective action of hypothermia in hypoxic and asphyxic newborns.
- MeSH
- hypotermie enzymologie MeSH
- krysa rodu Rattus MeSH
- L-laktátdehydrogenasa krev metabolismus MeSH
- mozková kůra enzymologie MeSH
- potkani Wistar MeSH
- stárnutí metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- L-laktátdehydrogenasa MeSH
The basic condition of life is capability to adapt not only to external but also to internal milieu conditions. I.e. receptors are able to change the intensity of signal transduction from the extracellular to the intracellular compartment in a short period. In a specific manner it concerns all receptor structures, both if they are located in cytoplasm or within the membrane. This review concentrates to the mechanisms existing in G protein-coupled receptors. Those protein structures can undergo a homologous or heterologous regulation. Homologous regulation means that only the properties of a receptor system influenced via extracellular signalling are changed. Heterologous regulation means, that receptor properties are changed despite that the extracellular signalling did not influence the receptor. It is possible to consider such changes as one of the level o homeostasis. Both homologous and heterologous regulations are essential for many physiological and pathophysiological processes. The most important examples of these processes, especially in the central nervous system, are reviewed here.
- MeSH
- lidé MeSH
- mozek fyziologie MeSH
- proteiny vázající GTP - regulátory fyziologie MeSH
- proteiny vázající GTP fyziologie MeSH
- receptory buněčného povrchu fyziologie MeSH
- signální transdukce * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- proteiny vázající GTP - regulátory MeSH
- proteiny vázající GTP MeSH
- receptory buněčného povrchu MeSH
- MeSH
- bludiště - učení * MeSH
- hypoxie * MeSH
- krysa rodu Rattus MeSH
- potkani Wistar MeSH
- tlak vzduchu * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
