Ceskoslovenska fysiologie最新文献

This paper describes the methodology and application of a wire myograph which has been used for the measurement of vascular reactivity. In an earlier years (pre-1970s) most of the information about the mechanical, morphological and pharmacological properties of vascular smooth muscle was confined only to larger arteries (mainly aorta). Whereas information about smaller arteries was purely inferred from perfusion experiments and histological examination. However, after mid-1970s Prof. Mulvany and Prof. Halpern developed and introduced an astonishing technique, a wire myography, to study the contractile responses of an isolated small resistance arteries (approximately 100-300 microm in internal diameter). This work describes some of the principles used in the investigation of the vessels, based on the use of the small vessel dual wire myograph. A dual myograph allows us simultaneous testing of two vessels. The technique allows segments of small arteries to be mounted as the ring preparations to the myograph chamber, and providing measurements of isometric responses. On the other hand, there are other techniques including an isobaric and isotonic mounting of arteries have been developed to date. The myograph has been used for the investigation of a variety of small and larger arteries and other tubular structures from a wide range of species. In the second part of this report we show an experimental example concerning measurement of endothelial functionality by technique described therein before.

The role of cholesterol in cell biology has been known for years. The sight of cholesteol biological function has changed after the discovery that the genetic disorder Smith-Lemli-Opitz syndrome is caused by a defect in cholesterol biosynthetic pathway. Cholesterol has an important role in regulation and modification of Hedgehog proteins, what links cholesterol to early embryonic development. Hedgehog proteins comprise a family of secreted signaling molecules that are essential for embryonic patterning and morphogenesis. The deficit of cholesterol during embryogenesis causes severe abnormalities in SLOS because of disrupt autoprocessing of hedgehog proteins. SLOS is an autosomal recessive disorder of sterol metabolism. The underlying pathogenetic basis for SLOS has been shown to be a deficiency of 7-dehydrocholesterol reductase, which catalyzes the last step in cholesterol biosynthesis. Reduced enzyme activity leads to a deficit of cholesterol and accumulation of precursor sterols. The human 7-dehydrocholesterol reductase gene (DHCR7) is localized on chromosome 11q 12-13.

Noradrenaline exerts many effects and mediates a number of functions in living organisms. Recently, the essential role of noradrenaline in the central nervous system (CNS) has emerged. Noradrenaline affects behaviors of individuals including a modulation of vigilance, arousal, attention, motivation, reward, and also learning and memory. Almost all brain noradrenergic fibers arise in brainstem nuclei designated A1-A7 (approximately half of neurons belongs to the brainstem nucleus, locus coeruleus). The effects of noradrenaline are mediated by two distinct super-families of receptors, named alpha- and beta-adrenoceptors. They are further divided into subgroups exhibiting specific roles in modulating behavior and cognition of animals. Adrenoceptors are located on the periphery as well as in the CNS and selective alpha- and beta-agonists and antagonists are used to assess their function. The purpose of this review is to summarize the findings about anatomy and physiology of the noradrenergic system in the CNS and discuss the pharmacological effects on specific adrenoceptor types. This paper also shows the importance of noradrenaline to maintain the cognitive processes such as attention, perception, and particularly the memory consolidation and retrieval. Disruption of these processes may result in symptoms of neuropsychiatric diseases and neurodegeneration.

Disodium cromoglycate (DSCG) is a compound commonly used in the treatment of allergic diseases. The effect of DSCG is due to its ability to stabilize the mast cell membrane and to prevent release of histamine and inflammatory mediators. Mast cells are also an abundant source of tissue metalloproteinases, serine proteases and growth factors, which play an important role in the processes of the tissue remodeling. In this view the DSCG is a substance which allows us to study the mechanisms of the pulmonary vascular bed remodeling in the experimental animals exposed to chronic hypoxia and in a phase of the recovery from hypoxia.

Stress and influence of stress hormones on organisms is interesting theme in many fields of study, e.g. human and veterinary medicine, zoology, ecology. Short time stress is not negative reaction, because it helps to alive. In stress response increase stress hormones levels (catecholamines, glucocorticoids), which cause elevated heart rate, blood pressure and acute elevation of blood glucose. These reactions cause better blood flow and acute utilization energy in vital organs, e.g. the brain, heart or muscles, and its cause better survive of organism. On the other hand, prolonged stress response is dangerous, e.g. chronically elevated blood pressure or levels blood glucose, sexual disorders, etc. If we know, which factor acts as stressor, we can eliminate or minimized its incidence. In case of transport its better to prefer the shortest way or better weather conditions. It's possible to improve welfare of animals in captivity, e.g. enrichment housing, physical conditions (temperature, humidity, light cycles, etc.), social structure in social animals.

In the last decades interdisciplinary research of memory takes place and it connects regions as cognitive psychology and neuroscience. Learning and memory are theoretical concepts, which enable to explain the fact that personal experience influences the behavior of the particular person. Memory has neuronal representation, which enables recollection of obtained experiences and information, and subsequently enables changes in behavior. The review describes events as registration, formation of memory trace as well as memory retrieval. Memory classification is possible according to many criteria, e.g. according to the length, its conscious recollection and the character of deposited information. Main types of memories are episodic memory (for facts and events), semantic memory (for general knowledge) and procedural memory (the ability to learn behavioral and cognitive abilities and algorithms). At present it is generally accepted that memory is a complicated process, which utilizes several brain structures at the same time that are called memory systems; according to the type of memory the experiences and information are deposited in various brain regions. The present research enables many approaches for determination of the sites of memory deposition. In the present period important role in memory localization have the brain imaging techniques. Together with the study of memory under physiological conditions, in the center of interest there is the study of memory during various life periods, under pathological conditions and diseases. The review is closed by the list of most important diseases in which we observe memory dysfunctions, including the retrograde and anterograde amnesias.

A number of vascular diseases, including hypertension, are characterised by endothelial dysfunction caused by alterations in the production and action of the endothelium-derived relaxing (EDRFs) and/or endothelium-derived contracting (EDCFs) factors. The spontaneously hypertensive rat (SHR) is one of the most widely studied animal models for human essential hypertension. Several similarities between human primary hypertension and hypertension in the SHR have been pointed out in both the pathophysiology and the clinical course of the hypertensive disease. In human hypertension as well as in SHR, endothelium-dependent relaxation may be attenuated and this endothelial dysfunction contributes to the increased peripheral resistance. However, various results concerning endothelium-dependent relaxation, including impairment, no change and improvement have been reported in experimental hypertension. Endothelial dysfunction in hypertension has been linked to decrease in NO bioavailability, reflecting the impaired generation of NO and/or the enhanced inactivation of NO by reactive oxygen species. There is evidence that increased vascular oxidative stress is present in SHR. Thus, it has been proposed that oxidative inactivation of NO may account for the endothelial dysfunction seen in SHR. On the other hand, several studies demonstrate elevated basal NO synthesis in SHR rats which may be an adapting mechanism, preventing them from excessive blood pressure elevation. However, the role of NO in hypertension in SHR and in humans remains still controversial. We hypothesize that the vascular bed studied, the effect of age as well as methodological aspects, such as "precontraction" with different vasoconstrictors as well as antioxidants added to the solution for determination of the vasoreactivity may contribute to the discrepancies among studies. Nevertheless, the involvement of endothelial function in hypertension remains subject of debate and further research is needed to complete our knowledge on the role of NO, reactive oxygen species and other endothelial factors in the regulation of vascular and cardiac function.

In the introduction we summarized basic information about memory and indicated studies, which were milestones in the study of memory. Basic studies of memory are reviewed and neurobiological approach is highlighted. The aim of this investigation is to find the relationship among basic facts about memory and what are the underlying mechanisms. This study deals with the participating brain structures, what happens on the synapses and how neurons are influenced. Substantial part of the review is devoted to synaptic plasticity and long-lasting potentiation (LTP). They represent the in vitro approaches, which help to discover mechanisms that participate in memory. The decisive role of AMPA and NMDA receptors and signaling cascades for memory are presented. The role of hippocampus and parahippocampal formation for memory storage is described in more details. Processes of memory consolidation and reconsolidation are presented as well as mechanisms, which modulate memory processes. The review is closed by the index theory, which explains complicated situation in storage and retrieval of memory.

Antioxidants and trace elements are using by hundreds millions of people. Effective are especially mixtures of antioxidants. Usually is declared only the composition of the tablets, but nowadays it is not satisfactory. Substantial is how much of the antioxidants is absorbed and where, how it increases the antioxidant capacity in the blood, which effect it has, the stability of them and who, how much, which and when they are to be used. It is also very important which antioxidants during the detoxication of free radicals react first and therefore they are soon exhausted and whether at all or how quickly can they be reduced back to an active component. In aging the antioxidant capacity decreases, it is influenced by the season, all of factors are to be taken in account. The absorption and the effect are influenced by the state of gastrointestinal tract, including the microbiological flora, pH, the size of the molecules, sometimes by partial oxygen tension in the blood. Free radicals are generated mostly after a load and therefore it is suitable to have the antioxidants capacity on a high level, it is possible to increase it during the load and it is recommended the administration of them after the load. Some authors recommend low doses of antioxidants five times a day. In some diseases the antioxidants are effluenced from the tissues to the blood and then there is a defficit in tissues of them. Important are the interferences during the absorption, their metabolism in organism; it may decrease their level or increase their effectivness, the metabolism can infuence to which tissues are the antioxidants deposited, and how long will stay the increased level of antioxidant capacity. The speed of elimination by urine and stool is also important. It is useful to know from which and how much of isomers the antioxidant is composed, because the single isomer may have a different effect. The origin of antioxidants is important, as natural antioxidants are usually more effective than the sythetic ones. The toxicity of the substances should not to be neglected. Storing of antioxidants sometimes deteriorate them, or sometimes they are contaminated by anabolic steroids. Some substances like phytates can bind them and so decrease their bioavavilability. Lipid soluble substances need lipids in the diet, some antioxidants are differently absorbed from different sources of nutrition. Genetic equipment is important as well. It is apparent that the administration of antioxidants and trace elements is not simple and that the informations of commercial preparates is usually not sufficient, probably in the future at least may be mentioned total antioxidant capacity.

Eicosanoids are twenty-carbon compounds derived from arachidonic acid. Lipoxygenases, cyclooxygenases and cytochrome P-450 enzymes contribute to their synthesis. Our review is focused on prostaglandins, leucotrienes, lipoxins, hepoxilins, hydroxyeicosatetraenoic acids, and epoxyeicosatrienoic acids. Most of these compounds have multiple functions and they also participate in blood pressure regulation and excretion of water and solutes in the kidney. They have some roles in the patogenesis of kidney disease, too. Both experimental models (mainly geneticaly modified mice and rats) and human epidemiological and genetical studies are used in the investigation of eicosanoid physiological and patophysiological functions. New information about their enzymatic regulations and receptors have already resulted in the development of new drugs, mainly antiasthmatics, but further investigation should bring about new results in the treatment of hypertension and other cardiovascular and renal diseases.