Hypoxia can cause basement membrane (BM) degradation in tissues. Matrix metalloproteinase 9 (MMP-9) is involved in various human cancers as well as BM degradation by downregulating type IV collagen (COL4). This study investigated the role of MMP9 in hypoxia-mediated BM degradation in rat bone marrow based on its regulation of collagen type IV alpha 1 chain (COL4A1). Eighty male rats were randomly divided into four groups based on exposure to hypoxic conditions at a simulated altitude of 7,000 m, control (normoxia) and 3, 7, and 10 days of hypoxia exposure. BM degradation in bone marrow was determined by transmission electron microscopy. MMP-9 levels were assessed by western blot and real-time PCR, and COL4A1 levels were assessed by western blot and immunohistochemistry. Microvessels BMs in bone marrow exposed to acute hypoxia were observed by electron microscopy. MMP-9 expression increased, COL4A1 protein expression decreased, and BM degradation occurred in the 10-, 7-, and 3-day hypoxia groups compared with that in the control group (all P<0.05). Hypoxia increased MMP-9 levels, which in turn downregulated COL4A1, thereby increasing BM degradation. MMP-9 upregulation significantly promoted BM degradation and COL4A1 downregulation. Our results suggest that MMP-9 is related to acute hypoxia-induced BM degradation in bone marrow by regulating COL4A1.
Chronic hypoxia results in hypoxic pulmonary hypertension characterized by fibrotization and muscularization of the walls of peripheral pulmonary arteries. This vessel remodeling is accompanied by an increase in the amount of lung mast cells (LMC) and the presence of small collagen cleavage products in the vessel walls. We hypothesize that hypoxia activates LMC, which release matrix metalloproteinases (MMPs) cleaving collagen and starting increased turnover of connective tissue proteins. This study was designed to determine whether in vitro hypoxia stimulates production of MMPs in rat LMC and increases their collagenolytic activity. The LMC were separated on the Percoll gradient and then were divided into two groups and cultivated for 24 h in 21 % O2 + 5 % CO2 or in 10 % O2 + 5 % CO2. Presence of the rat interstitial tissue collagenase (MMP-13) in LMC was visualized by immunohistological staining and confirmed by Western blot analysis. Total MMPs activity and tryptase activity were measured in both cultivation media and cellular extracts. Exposure to hypoxia in vitro increased the amount of cells positively labeled by anti-MMP-13 antibody as well as activities of all measured enzymes. The results therefore support the concept that LMC are an important source of increased collagenolytic activity in chronic hypoxia., H. Maxová, J. Novotná, L. Vajner, H. Tomášová, R. Vytášek, M. Vízek, L. Bačáková, V. Valoušková, T. Eliášová, J. Herget., and Obsahuje bibliografii a bibliografické odkazy
The aim of our study was to test the hypothesis, whether repeated allopurinol pre-treatment (in dose of 135 mg/kg s.c.) can influence changes of brain excitability caused by long-term hypoxia exposition in young immature rats. Rat pups were exposed together with their mother in to an intermittent hypobaric hypoxia (simulated altitude of 7 000 m) since the day of birth till the 11th day (youngest experimental group) or 17th day for 8 hours a day. Allopurinol was administered daily immediately before each hypoxia exposition. The duration of evoked afterdischarges (ADs) and the shape of evoked graphoelements were evaluated in 12, 18, 25 and 35-day-old freely moving male pups. Hypobaric hypoxia prolonged the duration of ADs in 12, 18 and 25-day-old rats. The ADs were prolonged in 35-day-old rats only after the first stimulation. Allopurinol shorted the duration of ADs only in 12-day-old pups. In older experimental group the effect of allopurinol treatment was less pronounced., K. Jandová, ... [et al.]., and Obsahuje seznam literatury
Oxygen supply was corrected in rabbits during the hepatic ischemia/reperfusion by means of different breathing mixtures: hypoxic (14.8 % O2+85.2 % N2), hyperoxic (78 % O2+20.2 % N2+ 1.8 % CO2), or hypercapnic (5 % CO2 in air). Hepatic ischemia was induced for 30 min by ligation of hepatic artery, reperfusion period lasted 120 min. Indices of blood oxygen transport (p50act, pCO2, pH, pO2, etc.) and prooxidant-antioxidant balance (Schiff bases, conjugated dienes, catalase, retinol, a-tocopherol) were measured in the blood and liver. The severity of reperfusion damage was evaluated by the activities of alanine and aspartate aminotransferases (ALT, AST) in the blood. Hepatic ischemia/reperfusion resulted in higher p50act in hepatic venous and mixed venous blood in all experimental groups. The changes of p50act were most marked in the hypercapnic group and were the weakest in the hypoxic group. The rise in p50act was accompanied by higher levels of lipid peroxidation products, ALT and AST in blood and liver homogenates, and by a simultaneous fall of α-tocopherol and retinol concentrations, except in the hypoxic group. Catalase activity at the end of reperfusion increased under normoxia, decreased under hyperoxia or hypercapnia and did not change under hypoxia. The moderate hypoxia during reperfusion was accompanied by a better balance between the mechanisms of reactive oxygen species production and inactivation that may be observed by optimal changes in p50act and reduced the hepatic damage in this pathological condition., V. V. Zinchuk, M. N. Khodosovsky, D. A. Maslakov., and Obsahuje bibliografii
Photothrombotic model of ischemia (PT) is based on free radical-mediated endothelial dysfunction followed by thrombosis. Free radicals are also involved in hypoxic preconditioning. We tested the sensitivity of PT to preconditioning with hypobaric hypoxia and to pretreatment with melatonin. In adult Wistar rats, after intravenous application of Rose Bengal, a stereo-tactically defined spot on the denuded skull was irradiated by a laser for 9 min. The first experimental group underwent hypobaric hypoxia three days before irradiation. In the second experimental group, melatonin was applied intraperitoneally one hour before irradiation. Three days after irradiation, animals were sacrificed, the brains perfused, and stained with TTC. Ischemic lesions were divided into grades (I, II, III). In the control group (where no manipulation preceded photothrombosis), most animals displayed deep damage involving the striatum (grade III). The group pre-exposed to hypoxia showed similar results. Only 28.57 % of the melatonin pretreated animals exhibited grade III lesions, and in 57.14 % no signs of lesions were detected. Pre-exposure to hypoxia was not protective in our model. Pretreatment with melatonin lead to a significant reduction of the number of large ischemic lesions. This result is probably caused by protection of endothelial cells by melatonin., I. Matějovská, K. Bernášková, D. Krýsl, J. Mareš., and Obsahuje bibliografii a bibliografické odkazy
Continuous normobaric hypoxia (CNH) renders the heart more tolerant to acute ischemia/reperfusion injury. Protein kinase C (PKC) is an important component of the protective signaling pathway, but the contribution of individual PKC isoforms under different hypoxic conditions is poorly understood. The aim of this study was to analyze the expression of PKCε after the adaptation to CNH and to clarify its role in increased cardiac ischemic tolerance with the use of PKCε inhibitory peptide KP-1633. Adult male Wistar rats were exposed to CNH (10 % O2, 3 weeks) or kept under normoxic conditions. The protein level of PKCε and its phosphorylated form was analyzed by Western blot in homogenate, cytosolic and particulate fractions; the expression of PKCε mRNA was measured by RT-PCR. The effect of KP-1633 on cell viability and lactate dehydrogenase (LDH) release was analyzed after 25-min metabolic inhibition followed by 30-min reenergization in freshly isolated left ventricular myocytes. Adaptation to CNH increased myocardial PKCε at protein and mRNA levels. The application of KP-1633 blunted the hypoxiainduced salutary effects on cell viability and LDH release, while control peptide KP-1723 had no effect. This study indicates that PKCε is involved in the cardioprotective mechanism induced by CNH., K. Holzerová, M. Hlaváčková, J. Žurmanová, G. Borchert, J. Neckář, F. Kolář, F. Novák, O. Nováková., and Obsahuje bibliografii
Carbon monoxide (CO) reversibly binds to hemoglobin forming carboxyhemoglobin (COHb). CO competes with O 2 for binding place in hemoglobin leading to tissue hypoxia. Already 30 % saturation of COHb can be deadly. Medical oxygen at atmospheric pressure as a therapy is not enough effective. Therefore hyperbaric oxygen O 2 inhalation is recommended. There was a question if partially ionized oxygen can be a better treatment at atmospheric pressure. In present study we evaluated effect of partially ionized oxygen produced by device Oxygen Ion 3000 by Dr. Engler in elimination of COHb in vitro experiments and in smokers. Diluted blood with different content of CO was purged with 5 l /min of either medicinal oxygen O 2 , negatively ionized O 2 or positively ionized O 2 for 15 min , then the COHb content was checked. In vivo study, 15 smokers inhaled o f either medicinal oxygen O 2 or negatively ionized O 2 , than we compared CO levels in expired air before and after inhalation. In both studies we found the highest elimination of CO when we used negatively ionized O 2 . These results confirmed the benefit of short inhalation of negatively ionized O 2 , in frame of Ionized Oxygen Therapy (IO 2 Th/Engler) which could be used in smokers for decreasing of COHb in blood., S. Perečinský, I. Kron, I. Engler, L. Murínová, V. Donič, M. Varga, A. Marossy, Ľ. Legáth., and Obsahuje bibliografii
Prolonged cultivation of separated rat lung mast cells (LMC) in vitro is necessary to better investigate a possible role of LMC in different stages of tissue remodeling induced by hypoxia. Rat lung mast cells (LMC) were sepa rated using a protocol including an improved proteolytic extracti on and two subsequent density gradient separations on Ficoll-P aque PLUS and a new generation of Percoll, i.e. Percoll PLUS. Instead of usual isotonic stock Percoll solution, an alternative “asymptotically isotonic” stock solution was more successful in our density separation of LMC on Percoll PLUS. Separated cells were cultivated for six days in media including stem cell factor, interleu kins IL-3 and IL-6, and one of two alternative mixtures of antibi otics. These cultivations were performed without any contaminatio n and with only rare changes in cell size and morphology. Model co-cultivation of two allogenic fractions of LMC often caused considerable rapid changes in cell morphology and size. In contrast to these observations no or rare morphological changes were found after cultivation under hypoxic conditions. In conclusions, we modified separation on Percoll PLUS to be widely used, altered LMC separation with respect to purposes of long-lasti ng cultivation and observed some model morphological changes of LMC., J. Kubrycht ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Our present focus on the hypoxic immature heart is driven by clinical urgency: cyanotic congenital cardiac malformations remain the single largest cause of mortality from congenital defects and ischemic heart disease is no more the disease of the fifth and older decades but its origin as well as risk factors are present already during early ontogeny. Moreover, the number of adult patients operated for cyanotic congenital heart disease during infancy steadily increases. This group approaches the age of the rising risk of serious cardiovascular diseases, particularly ischemic heart disease. Experimental results have clearly shown that the immature heart is significantly more tolerant to oxygen deficiency than the adult myocardium. However, the mechanisms of this difference have not yet been satisfactorily clarified; they are likely the result of developmental changes in cardiac energy metabolism, including mitochondrial function. The high resistance of the newborn heart cannot be further increased by ischemic preconditioning or adaptation to chronic hypoxia; these protective mechanisms appear only with decreasing tolerance during development. Resistance of the adult myocardium to acute oxygen deprivation may be significantly influenced by perinatal hypoxia. These results suggest that the developmental approach offers new possibilities in the studies of pathogenesis, prevention and therapy of critical cardiovascular diseases., B. Ošťádal ... [et al.]., and Obsahuje seznam literatury
Neonatal hypoxic-ischemic encephalopathy is a disorder with heterogeneous manifestation due to asphyxia during perinatal period. It affects approximately 3-12 children per 1000 live births and cause death of 1 million neonates worldwide per year. Besides, motor disabilities, seizures, impaired muscle tone and epilepsy are few of the consequences of hypoxic-ischemic encephalopathy. Despite an extensive research effort regarding various treatment strategies, therapeutic hypothermia with intensive care unit supportive treatment remains the only approved method for neonates who have suffered from moderate to severe hypoxicischemic encephalopathy. However, these protocols are only partially effective given that many infants still suffer from severe brain damage. Thus, further research to systematically test promising neuroprotective treatments in combination with hypothermia is essential. In this review, we discussed the pathophysiology of hypoxic-ischemic encephalopathy and delved into different promising treatment modalities, such as melatonin and erythropoietin. However, preclinical studies and clinical trials are still needed to further elucidate the mechanisms of action of these modalities.