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272. The effects of head cooling on endurance and neuroendocrine responses to exercise in warm conditions
- Creator:
- Ansley, L., Marvin, G., Sharma, A., Kendall, M. J., Jones, D. A., and Bridge, M. W.
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, hypertermie, tělesná cvičení, únava, physiology, hyperthermia, exercises, fatigue, prolactin, head cooling, 14, and 612
- Language:
- English
- Description:
- The present study investigated the effects of head cooling during endurance cycling on performance and the serotonergic neuroendocrine response to exercise in the heat. Subjects exercised at 75 % VO2max to volitional fatigue on a cycle ergometer at an ambient temperature of 29±1.0 °C, with a relative humidity of approximately 50 %. Head cooling resulted in a 51 % (p<0.01) improvement in exercise time to fatigue and Borg Scale ratings of perceived exertion were significantly lower throughout the exercise period with cooling (p<0.01). There were no indications of peripheral mechanisms of fatigue either with, or without, head cooling, indicating the importance of central mechanisms. Exercise in the heat caused the release of prolactin in response to the rise in rectal temperature. Head cooling largely abolished the prolactin response while having no effect on rectal temperature. Tympanic temperature and sinus skin temperature were reduced by head cooling and remained low throughout the exercise. It is suggested that there is a co-ordinated response to exercise involving thermoregulation, neuroendocrine secretion and behavioural adaptations that may originate in the hypothalamus or associated areas of the brain. Our results are consistent with the effects of head cooling being mediated by both direct cooling of the brain and modified cerebral artery blood flow, but an action of peripheral thermoreceptors cannot be excluded., L. Ansley, G. Marvin, A. Sharma, M. J. Kendall, D. A. Jones, M. W. Bridge., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
273. The effects of pertussis toxin-treatment on integrated vasoactive response of vascular system in spontaneously hypertensive rats
- Creator:
- Soňa Čačányiová, Kristek, F., Jaroslav Kuneš, and Josef Zicha
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- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, krevní tlak, acetylcholin, physiology, blood pressure, acetylcholine, spontaneously hypertensive rats (SHR), pertussis toxin, noradrenaline, bradykinin, vasoactive responses, 14, and 612
- Language:
- English
- Description:
- We investigated the effect of pertussis toxin (PTX) on hypotensive response induced by acetylcholine (ACh) and bradykinin (BK) and on noradrenaline (NA)-induced pressor response in spontaneously hypertensive rats (SHR). Fifteen-week-old Wistar rats and age-matched SHR were used. Half of SHR received PTX (10 μg/kg/i.v.) and the experiments were performed 48 h later. After the anesthesia the right carotid artery was cannulated in order to record blood pressure (BP). The hypotensive response to ACh was enhanced in SHR compared to Wistar rats. After pretreatment of SHR with PTX the hypotensive response to ACh was reduced compared to untreated SHR and it was also diminished in comparison to Wistar rats. Similarly, the hypotensive response to BK was also decreased after PTX pretreatment. The pressor response to NA was increased in SHR compared to Wistar rats. NA-induced pressor response was considerably decreased after PTX pretreatment compared to untreated SHR. In conclusion, the enhancement of hypotensive and pressor responses in SHR was abolished after PTX pretreatment. Our results suggested that the activation of PTX-sensitive inhibitory Gi proteins is involved in the regulation of integrated vasoactive responses in SHR and PTX pretreatment could be effectively used for modification of BP regulation in this type of experimental hypertension., S. Čačányiová, F. Kristek, J. Kuneš, J. Zicha., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
274. The NADPH oxidase inhibitors iodonium diphenyl and cadmium sulphate inhibit hypoxic pulmonary vasoconstriction in isolated rat pulmonary arteries
- Creator:
- Jones, R. D., Thompson, J. S., and Alyn H. Morice
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- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, NADPH oxidase, hypoxic pulmonary vasoconstriction, iodonium diphenyl cadmium sulphate, isolated rat pulmonary artery, 14, and 612
- Language:
- English
- Description:
- Interest surrounds the role of an NADPH oxidase-like enzyme in hypoxic pulmonary vasoconstriction (HPV). We have studied the effects of the NADPH oxidase inhibitors iodonium diphenyl (ID) and cadmium sulphate (CdSO4) upon HPV of isolated rat pulmonary arteries (n = 73, internal diameter 545± 23 mm). Vessels were preconstricted with prostaglandin F2a (PGF2a, 0.5 or 5 mM) prior to a hypoxic challenge. ID (10 or 50 mM), CdSO4 (100 mM) or vehicle (50 ml) was added for 30 min before re-exposure to PGF2a and hypoxia. ID and CdSO4 significantly inhibited HPV. In vessels preconstricted with 5 mM PGF2a, ID (10 and 50 mM) reduced HPV from 37.4± 5.6 % to 9.67± 4.4 % of the contractile response elicited by 80 mM KCl (P<0.05) and from 30.1± 5.0 % to 0.63± 0.6% 80 mM KCl response (P<0.01), respectively. CdSO4 (100 mM) reduced HPV from 29.4±4.0 % to 17.1±2.2% 80 mM KCl response (P<0.05). In vessels preconstricted with 0.5 mM PGF2a, ID (10 and 50 mM) reduced HPV from 16.0± 3.15% to 3.36± 1.44 % 80 mM KCl response (P<0.01) and from 15.0± 1.67 % to 2.82± 1.40 % 80 mM KCl response (P<0.001), respectively. Constriction to PGF2a was potentiated by ID. ID and CdSO4, at concentrations previously shown to inhibit neutrophil NADPH oxidase, attenuate HPV in isolated rat pulmonary arteries. This suggests that an NADPH oxidase-like enzyme is involved in HPV and could act as the pulmonary oxygen sensor., R. D. Jones, J. S. Thompson, A. H. Morice., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
275. The origin of 7α-hydroxy-dehydroepiandrosterone and its physiological role: a history of discoveries
- Creator:
- Luboslav Stárka
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- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, 11β-hydroxysteroid dehydrogenase, CYP7B, immunomodulatory effects, occurrence, dehydroepiandrosterone, 7α-hydroxy-dehydroepiandrosterone, neurosteroid, 14, and 612
- Language:
- English
- Description:
- Nearly 60 years has elapsed since the first isolation and identification of 7α-hydroxy-dehydroepiandrosterone, and in that time much information has been gained on its occurrence, metabolism, ontogeny, immunomodulatory activity, cell proliferation, cortisol control in local tissues and neuroactivity. Additional knowledge about this steroid may elucidate its role in obesity, neurodegenerative disturbances such as Alzheimer’s disease, or psychiatric disorders such as schizophrenia or depression. This review aims to provide a comprehensive summary of the available literature on 7α-hydroxydehydroepiandrosterone., L. Stárka., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
276. The pacemaker activity of interstitial cells of Cajal and gastric electrical activity
- Creator:
- Petra Čamborová, Hubka, P., Igor Šulla, and Ivan Hulín
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, interstitial cells of Cajal, gastric electrical activity, pacemaker of the stomach, kit-receptor, electrogastrography, 14, and 612
- Language:
- English
- Description:
- Interstitial cells of Cajal (ICC) are the pacemaker cells in the gut. They have special properties that make them unique in their ability to generate and propagate slow waves in gastrointestinal muscles. The electrical slow wave activity determines the characteristic frequency of phasic contractions of the stomach, intestine and colon. Slow waves also determine the direction and velocity of propagation of peristaltic activity, in concert with the enteric nervous system. Characterization of receptors and ion channels in the ICC membrane is under way, and manipulation of slow wave activity markedly alters the movement of contents through the gut. Gastric myoelectrical slow wave activity produced by pacemaker cells (ICC) can be reflected by electrogastrography (EGG). Electrogastrography is a perspective non-invasive method that can detect gastric dysrhythmias associated with symptoms of nausea or delayed gastric emptying., P. Čamborová, P. Hubka, I. Sulková, I. Hulín., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
277. The pH-dependent and enzymatic release of cytarabine from hydrophilic polymer conjugates
- Creator:
- Pola, R., Olga Janoušková, and Tomáš Etrych
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- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, HPMA copolymers, drug delivery system, nucleoside analogues, cytarabine, 14, and 612
- Language:
- English
- Description:
- Cytarabine is one of the most efficient drugs in the treatment of hematological malignancies. In this work, we describe the synthesis and characterization of two different polymer conjugates of cytarabine that were designed for the controlled release of cytarabine within the leukemia cells. Reactive copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) and 3-(3-methacrylamidopropanoyl)thiazolidine-2-thione) or 3-(Nmethacryloylglycyl- phenylalanylleucylglycyl)thiazolidine-2-thione were used in the study as reactive polymer precursors for reaction with cytarabine. The enzymatic release of cytarabine from the conjugate containing a GFLG spacer utilizing cathepsin B was verified. In addition to enzymolysis, the pH-dependent hydrolysis of cytarabine from both copolymers was also confirmed. Approximately 40 % and 20 % of the drug was released by spontaneous hydrolysis at pH 7.4 within 72 h from the polymer conjugates with the GFLG and β-Ala spacers, respectively. At pH 6.0, the spontaneous hydrolysis slowed down, and less than 10 % of the drug was liberated within 72 h. The results of the cytotoxicity evaluation of the polymer conjugates in vitro against various cell lines showed that the cytotoxicity of the polymer conjugates is approximately three times lower in comparison to free cytarabine., R. Pola, O. Janoušková, T. Etrych., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
278. The pore architecture of the cystic fibrosis transmembrane conductance regulator channel revealed by co-mutation in pore-forming transmembrane regions
- Creator:
- Qian, Feng, Liu, Lian, Liu, Zhenzhen, and Lu, Chengbiao
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, cystic fibrosis transmembrane conductance regulator, patch clamp, site-directed mutagenesis, 14, and 612
- Language:
- English
- Description:
- The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel contains 12 transmembrane (TM) regions that are presumed to form the channel pore. However, t here is no direct evidence clearly illustrating the involvement of these transmembr ane regions in the actual CFTR pore structure. To obtain insight into the architecture of the CFTR channel pore, we used patch clamp recording techniques and a strategy of comutagenesis of two potential pore-forming transmembrane regions (TM1 and TM6) to investigate the collaboration of these two TM regions. We performed a range of specific functional assays comparing the single channel conductance, anion binding, and anion selectivity properties of the co -mutated CFTR variants, and the results indicated that TM1 and TM6 play vital roles in forming the channel pore and, thus, determine the functional properties of the channel. Furthermore, we provide d functional evidence that the amino acid threonine (T338) in TM6 has synergic effects with lysine (K95) in TM1. Therefore, we propose that these two residues have functional collaboration in the CFTR channel pore and may collectively form a selective filter ., F. Qian, L. Liu, Z. Liu, C. Lu., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
279. The role of ACTH in the pathogenesis of polycistic ovarian syndrome in rats: hormonal profiles and ovarian morphology
- Creator:
- Baravalle, C., Salvetti, N. R., Mira, G. A., Lorente, J. A., and Ortega, Hugo H.
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, vaječníky, syndrom polycystických ovarií, stres (fyziologie), krysa obecná, physiology, ovaries, polycystic ovary syndrome, stress (physiology), Rattus rattus, ACTH, ACTH (adrenocorticotrophic hormone), 14, and 612
- Language:
- English
- Description:
- Numerous hypotheses have been proposed about the pathogenesis of the polycystic ovarian syndrome (PCOS). However, hormonal control of persistent follicles has not be enestablished. The objective of the present study was to compare the follicular structure and hormonal profiles of rats treated with the adrenocor ticotrophic hormone (ACTH) with two experimental models of PCOS. ACTH-treated animals were compared with those exposed to continuous light, those treated with estradiol valerate, and with control (in proestrous and diestrous). Serum hormone levels, histomorphometrical changes, and immunoexpression of vimentin, cytokeratins, cadherins, and proliferating cell nuclear antigen (PCNA) were examined. Treatment with ACTH resulted in an elevation of corticosterone secretion with LH reduction but without changes in ovarian morphology. Although stress (or ACTH) stimulation may be only one of pathophysiological mechanisms involved in follicular cystathogenesis in other species, we do not have important evidence to suppose that this would happen in rats., C. Bavaralle, N. R. Salvetti, G. A. Mira, J. A. Lorente, H. H. Ortega., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
280. The role of membrane fluidity changes and thiobarbituric acid-reactive substrances production in the inhibition of cerebral cortex Na+/K+-ATPase activity
- Creator:
- Hana Rauchová, Zdeněk Drahota, and Jitka Koudelová
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, cerebral cortex membranes, lipid peroxidation, membrane fluidity, 14, and 612
- Language:
- English
- Description:
- Lipid peroxidation of rat cerebral cortex membranes was induced by Fe2+/ADP and ascorbate. The rate of Na+/K+-ATPase inhibition was correlated with the increase of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes (CD) and with membrane fluidity changes. Our data showed that membrane fluidity changes (evaluated by fluorescence steady-state anisotropy measurements) can participate in Na+/K+-ATPase inhibition during the initial period of lipid peroxidation process, whereas during the following period the enzyme inhibition correlates only with TBARS and CD production., H. Rauchová, Z. Drahota, J. Koudelová., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public