oxygen affinity
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Vysoké nadmorské výšky vyvolávajú hypobarickú hypoxiu, ktorá mení transport kyslíka z plúc do tkanív. Autor sa v prvej časti súborného referátu zaoberá jeho transportom v pľúcach a v krvi. V úvode približuje zmeny atmosférického tiaku a parciálneho tiáku kyslíka v rozsahu výšok, kde žijú ľudia. Transport kyslíka v pľúcach závisí od pľúcnej ventilácie, prenosu kyslíka cez pľúcne tkanivo a od pľúcnej cirkulácie. Transport kyslíka v krvi závisí od počtu erytrocytov, stupňa erytropoézy a jej stimulovania erytropoetinom, objemu pretečenej krvi v cievach za časovú jednotku, artériovenóznej diferencie kyslíka, afinity hemoglobínu ku kyslíku a od deformability erytrocytov.
Higher altitudes produce a hypobaric hypoxia changing the transport of oxygen from the lungs to the tissues. In the first part of review article the author deals with its transport in the lungs and blood. In introduction he clarifies alterations of the atmospheric pressure and partial pressure of oxygen in the range of altitudes where people dwell. The oxygen transport in the lungs depends on the pulmonary ventflation, transport of oxygen through the pulmonary tissue, and on the pulmonary circulation. Transport of oxygen in the blood is dependent on the count of erytrocytes, level of erythropoiesis and its stimulation by erythropoietin, on the volume of blood flow in vessels during a time unit, arterial-venous oxygen difference, haemoglobin affinity for oxygen and on deformability of erythrocytes.
- MeSH
- erythropoetin MeSH
- hemoglobiny MeSH
- hypoxie etiologie MeSH
- kyslík MeSH
- lidé MeSH
- nadmořská výška MeSH
- plicní ventilace MeSH
- rychlost toku krve MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
- MeSH
- alanin metabolismus MeSH
- hemoglobiny abnormální analýza genetika izolace a purifikace MeSH
- kyselina asparagová metabolismus MeSH
- kyslík metabolismus MeSH
- lidé MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH
- polycytemie krev MeSH
- sekvence aminokyselin MeSH
- Check Tag
- lidé MeSH
- MeSH
- alanin metabolismus MeSH
- hemoglobiny abnormální analýza genetika izolace a purifikace MeSH
- kyselina asparagová metabolismus MeSH
- kyslík metabolismus MeSH
- lidé MeSH
- polycytemie krev MeSH
- sekvence aminokyselin MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, U.S. Gov't, P.H.S. MeSH
- Geografické názvy
- Československo MeSH
Cytochrome c oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome c affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p50 (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism.
