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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Uptake of external glucose and production of lactate were measured in freshly-excised bovine articular cartilage under O2 concentrations ranging from 21% (air) to zero (N2-bubbled). Anoxia (O2 concentration < 1% in the gas phase) severely inhibited both glucose uptake and lactate production. The decrease in lactate formation correlated closely with the decrease in glucose uptake, in a mole ratio of 2:1. This reduction in the rate of glycolysis in anoxic conditions is seen as evidence of a negative Pasteur effect in bovine articular cartilage. Anoxia also suppressed glycolysis in articular cartilage from horse, pig and sheep. Inhibitors acting on the glycolytic pathway (2-deoxy-D-glucose, iodoacetamide or fluoride) strongly decreased aerobic lactate production and ATP concentration, consistent with the belief that articular cartilage obtains its principal supply of ATP from substrate-level phosphorylation in glycolysis. Azide or cyanide lowered the ATP concentration in aerobic cartilage to approximately the same extent as did anoxia but, because glycolysis (lactate production) was also inhibited by these treatments, the importance of any mitochondrial ATP production could not be assessed. A negative Pasteur effect would make chondrocytes particularly liable to suffer a shortage of energy under anoxic conditions. Incorporation of [35S]sulphate into proteoglycan was severely curtailed by treatments, such as anoxia, which decreased the intracellular concentration of ATP.
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PMID:Evidence for a negative Pasteur effect in articular cartilage. 900 6

The effects of cyanide, anoxia, and temperatures varying from 2 to 42 C on the cell membrane electropotential difference (PD) of washed and freshly excised corn roots have been determined. Respiration rates of freshly excised root segments in response to cyanide and to varying temperatures were also measured. The cell membrane PD of roots which had been washed for 12 to 15 hours was almost insensitive to cyanide and anoxia but sensitive to low temperature. In contrast, the cell membrane PD of freshly excised roots was reversibly depolarized by all three treatments, cyanide depolarized from -117 to -86 millivolts and the sequential imposition of anoxia further lowered the PD to -69 millivolts. Anoxia applied first depolarized maximally and the PD was not further lowered by sequential cyanide treatment. Arrhenius plot analysis of the temperature response of respiration showed an apparent transition at 13 C with an activation energy of 20.0 kilocalories per mole below and 8.8 kilocalories per mole above the transition temperatures. The energy of activation for repolarization of PD is much higher; 53.4 kilocalories per mole below 7 to 8 C and 25.4 kilocalories per mole above this apparent transition. The energy requirement for polarization of the cell membrane PD was calculated based on the temperature responses of the cell membrane PD and respiration. It was estimated that 3.5% of the energy output from respiration at 22 C is required for cell polarization. It is unlikely that ion transport is limited by energy availability below the 8 C transition in this chill sensitive species.
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PMID:An Analysis of the Relationship between Respiration and the Transmembrane Potential in Corn Roots. 1666 59