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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The success of heart transplantation is limited by the negative correlation between the length of the cold ischemic storage period and the quality of functional recovery. We use 23Na, 31P NMR spectroscopy, and hemodynamic parameters to describe temperature-dependent changes in sodium influx and the concentration of phosphorus high-energy compounds during different storage periods. Perfusion with Krebs-Henseleit solutions containing Dy(TTHA)3- permitted discrimination of intra- and extracellular sodium during cold ischemic storage. The 23Na NMR visibilities under the acquisition and processing parameters used in our experiments were 40 +/- 4% for the intracellular compartment and 97 +/- 11% for the extracellular compartment. At 4 degrees C, the intracellular Na+ accumulation exceeded that observed at 15 and 22 degrees C. The ATP and PCr depletion rates were much lower at 4 degrees C and the left ventricular contractility was higher after longer periods of storage, as the storage temperature decreased. The intracellular Na+ concentration cannot serve as a marker for the postischemic recovery probability. The relative activity of the Na/K ATPase pumps is not correlated with the preservation success. However, intracellular sodium ion accumulation is a major factor in the time lag of the reperfusion recovery.
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PMID:Sodium ion transport in rat hearts during cold ischemic storage: 23Na and 31P NMR study. 146 Nov 25

The metabolism of calcium ion (Ca2+) in myocytes in ischemia-reperfusion injury under extracorporeal circulation (ECC) was studied by cytochemistry and electron microscopy. Ten mongrel dogs were under ECC with aortic cross-clamping for 120 minutes. A cold GIK crystalloid cardioplegic solution was infused via the aortic root intermittently during ischemia, and the myocardial temperature was maintained at 5-10 degrees C with ice slush. The morphological changes of Ca(2+)-ATPase activity in myocytes were estimated using the "lead citrate method". The activities of mitochondria, which had been temporarily decreased just before reperfusion, increased immediately after reperfusion and decreased again 60 minutes later. Electromicroscopy revealed swelling of mitochondria and laceration of myofibrils as well as intracellular edema 60 minutes after reperfusion. Immediately after reperfusion and 60 minutes later, creatine phosphokinase iso-enzyme (CK-MB) release in coronary sinus blood was significantly (p < 0.01) greater than that before the start of ECC. Anaerobic metabolism immediately after reperfusion was more active than that before aortic cross-clamping, as demonstrated by changes in excess lactate (delta XL) and redox potential (delta Eh) of lactate and pyruvate (delta XL, p < 0.05; delta Eh, p < 0.01). Thus, in ischemia-reperfusion injury, alterations of Ca(2+)-ATPase activity of mitochondria reflect the functional and morphological viability of the myocardium. Immediately and 60 minutes after reperfusion, the level of thiobarbituric acid was significantly (p < 0.01) higher and the level of alpha-tocopherol was significantly (p < 0.01) less than respective levels before the start of ECC.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Metabolism of Ca2+ in myocytes and peroxidation products in ischemia-reperfusion injury under extracorporeal circulation]. 148 36

We studied changes in myofibrillar function and protein profiles after complete global ischemia with anoxia in rat hearts. Hearts were exposed to global ischemia and anoxia (CGI) for 30 or 60 minutes at 37 degrees C, and myofibrils were prepared for measurement of Ca(2+)-dependent Mg(2+)-ATPase activity at pH 7.0 and 6.5. Hearts incubated in cold saline (1 +/- 1 degrees C) and nonincubated hearts served as controls. Maximum ATPase activity was unchanged at pH 7.0 and pH 6.5 in myofibrils from hearts treated with 30 or 60 minutes of CGI. At pH 7.0, the Hill coefficient, which is an index of cooperative interactions among thin-filament proteins, was unchanged after 30 minutes of CGI but was significantly increased after 60 minutes of CGI. A similar trend for increased cooperativity was observed when myofibrillar ATPase activity was measured at pH 6.5 in myofibrils from rat hearts made ischemic for 30 or 60 minutes. Both 30 and 60 minutes of CGI resulted in increased pCa50 values (half-maximally activating free [Ca2+]) at pH 7.0 and pH 6.5. Densitometric analysis of myofibrillar proteins separated with sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that troponin I and troponin T were degraded during 60 minutes of CGI. Two new protein bands appearing in ischemia-treated myofibrils were identified as partially degraded troponin I and troponin T with Western blots. The troponin I fragment could be phosphorylated by cAMP-dependent protein kinase. In addition, we observed phosphorylation of a protein band that corresponded to myosin light chain-2 in myofibrils from CGI-treated hearts. These results suggest that degradation of thin-filament proteins may contribute to the changes in cooperativity of Ca2+ regulation of ATPase activity observed in the myofibrils from rat hearts exposed to CGI.
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PMID:Alterations in myofibrillar function and protein profiles after complete global ischemia in rat hearts. 153 Nov 86

Studies to establish the structure/function relationships of oligomycin sensitivity-conferring protein (OSCP) of mitochondrial ATP synthase were carried out using genetic engineering and biochemical approaches. A full-length cDNA clone encoding OSCP was isolated from a bovine heart cDNA library, and the mature form of OSCP was expressed in Escherichia coli using plasmid expression vector pKP1500. Recombinant OSCP was found to accumulate in the cytoplasmic inclusion bodies, by virtue of which the recombinant protein could be purified to greater than 85% purity by simple low speed centrifugation of cell lysates. Recombinant OSCP was found to be indistinguishable from OSCP isolated from mitochondria with respect to (i) apparent molecular mass on sodium dodecyl sulfate gel electrophoresis, (ii) immunological reactivity to anti-OSCP serum, (iii) biological activity in restoring oligomycin-sensitive ATPase and Pi-ATP exchange activities to OSCP-depleted ATP synthase complexes, and (iv) insensitivity of the biological activity to sulfhydryl-directed alkylating reagents. The amino-terminal sequence of the recombinant protein revealed that the initiating methionine was not removed by E. coli, although that apparently did not affect protein folding or its biological activity. Data on nested deletion mutations starting from the carboxyl terminus in OSCP demonstrated that, in each instance, the mutant form was expressed and the protein product was sequestered in cytoplasmic inclusion bodies, similar to the wild-type form. However, none of the variants, including the one in which only the last 10 residues were deleted, was able to restore cold-stable oligomycin-sensitive ATPase or Pi-ATP exchange activity in OSCP-depleted complexes. Taken together, these data suggest that amino acid residues 181-190 (or some of the residues in this region) in the OSCP sequence may be important for OSCP-F1 interactions.
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PMID:Oligomycin sensitivity-conferring protein (OSCP) of mitochondrial ATP synthase. The carboxyl-terminal region of OSCP is essential for the reconstitution of oligomycin-sensitive H(+)-ATPase. 153 27

The mechanisms of Na, K-ATPase dysfunction in red blood cells of patients suffering from glomerulonephritis and renal failure were studied by means of "functional loads" of an enzyme, enabling not only the activity but also the routine of Na, K-ATPase to be determined. Evidence is provided for the presence of immunotoxic factor on the patients' red blood cells, in the plasma of venous blood and serum of arterial blood. Its excretion from the patients' body and recovery of the routine of Na, K-ATPase have been simulated in vivo and in vitro. The cold immunoglobulin nature of the inhibitor related to the M-chains of IgM was established. It has been shown that the mechanisms of formation of the immunopathogenesis of glomerulonephritis are associated with the appearance of cold autoantibodies and their fragments on blood cell membranes, bringing about a decrease of the activity of Na, K-ATPase and modifying its routine.
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PMID:[The mechanism of Na+--K+ pump dysfunction in the erythrocytes of patients with glomerulonephritis and kidney failure]. 165 66

This paper reports the experimental research on the cold-constitution (CC) and the heat-constitution (HC). The authors have selected the CC and HC in Wistar rats, and have determined adenylate kinase (ADK) activities: energy charge and Na(+)-K(+)-ATPase activities in liver, the amounts of T3, T4, progesterone, testosterone and estradiol in serum, 17-KS in urine. The ADK activities were markedly different between the HC group and the CC group (P less than 0.01). The Na(+)-K(+)-ATPase activities were obvious different between the HC group and the CC group (P less than 0.05). The energy charge of the HC group has increased by 16.1% as compared with the CC group in cells. The contents of T3, T4 of the HC group were higher than the CC group (P less than 0.01). The content of progesterone of the HC group was higher than the CC group as well (P less than 0.01). The contents of E2 and 17-KS had no differences. These results indicated that differences between the CC and the HC were based on the basic metabolism and its regulators.
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PMID:[Experimental research on the cold-constitution and the heat-constitution (I)]. 165 98

Brown adipose tissue (Na(+)-K+)-ATPase activity, in vitro glucose uptake and 2-aminoisobutyric acid uptake, as well as mitochondrial GDP-binding and succinate dehydrogenase activity were determined in order to study the relationship between these parameters in control, cold acclimated and cafeteria-fed rats. GDP-binding, (Na(+)-K+)-ATPase and glucose uptake were increased in interscapular brown adipose tissue from cold-acclimated and cafeteria-fed rats, whereas 2-aminoisobutyric acid uptake was only increased in cafeteria-fed rats. GDP-binding and (Na(+)-K+)-ATPase activity showed a high correlation coefficient suggesting a parallel modulation of both systems, which would probably share a common regulation mechanism.
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PMID:Parallel modulation of brown adipose tissue GDP-binding, substrate uptake and (Na(+)-K+)-ATPase activity in the rat. 166 Dec 74

Na,K- and Ca,Mg-ATPase activities in the membrane of red blood cells (RBC) were determined in glutamate treated obese rats (GOR). Both activities are related oppositely. In the obese rats the Na,K-ATPase is higher but the efficiency in maintenance of Na/K-ion concentration gradients is diminished. Ca,Mg-ATPase is decreased in GOR. Under the hypermetabolic condition of cold adaption the Na,K-ATPase activity decreases and the Ca,Mg-ATPase activity rises in both animal groups. The Na,K-ATPase activity in RBC-membranes is positively related to fat accumulation and age.
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PMID:Changes of ATPase activities in erythrocytes of rats with hypothalamic obesity. 166 43

The metabolic adjustments which occur in rat liver cells during the first days of cold exposure have been investigated. We have measured both mitochondrial mass and oxidative capacities as well as ATP production after five and 10 days of cold exposure. In addition, we have measured plasma membrane Na+/K(+)-ATPase activity. Cold exposure elicited a significant increase in mitochondrial mass as well as in state 3 oxidative rates and ATP production in isolated mitochondria using various substrates. Moreover, our results show that Na(+)-pumping activity significantly increased after both five and 10 days of cold exposure. Our results suggest that during the first days of cold exposure liver cells undergo alterations which are useful for survival in the cold.
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PMID:Hepatic selective adjustments in short-term cold exposed rats. 166 84

The secA gene product is an autoregulated, membrane-associated ATPase which catalyzes protein export across the Escherichia coli plasma membrane. Previous genetic selective strategies have yielded secA mutations at a limited number of sites. In order to define additional regions of the SecA protein that are important in its biological function, we mutagenized a plasmid-encoded copy of the secA gene to create small internal deletions or duplications marked by an oligonucleotide linker. The mutagenized plasmids were screened in an E. coli strain that allowed the ready detection of dominant secA mutations by their ability to derepress a secA-lacZ protein fusion when protein export is compromised. Twelve new secA mutations were found to cluster into four regions corresponding to amino acid residues 196 to 252, 352 to 367, 626 to 653, and 783 to 808. Analysis of these alleles in wild-type and secA mutant strains indicated that three of them still maintained the essential functions of SecA, albeit at a reduced level, while the remainder abolished SecA translocation activity and caused dominant protein export defects accompanied by secA depression. Three secA alleles caused dominant, conditional-lethal, cold-sensitive phenotypes and resulted in some of the strongest defects in protein export characterized to date. The abundance of dominant secA mutations strongly favors certain biochemical models defining the function of SecA in protein translocation. These new dominant secA mutants should be useful in biochemical studies designed to elucidate SecA protein's functional sites and its precise role in catalyzing protein export across the plasma membrane.
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PMID:Isolation and analysis of dominant secA mutations in Escherichia coli. 182 69


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