Continuous Oxygen Uptake Research Articles

Arterial and Mixed Venous Blood Gas Status during Apnoea of Intubation — Proof of the Christiansen-Douglas-Haldane Effect in Vivo

The Christiansen-Douglas-Haldane effect, in short the Haldane effect, describes the dependence of the CO2 binding of blood on the degree of oxygenation of haemoglobin. Under the physiological conditions of an 'open' system between blood and alveoli the partial pressure of arterial CO2 (PaCO2), must be less than that of mixed venous blood (PvCO2). During the unphysiological conditions of a 'closed' system, e.g. hyperoxic apnoea, i.e. continuous oxygen uptake without CO2 delivery by the lungs, the PaCO2 will not only approximate the PvCO2 but will even exceed it. Without the Haldane effect, rapid adjustment of PaCO2 to PvCO2 would be expected during apnoea due to the lack of CO2 excretion. If, however, as undertaken in this study, ongoing oxygenation (high alveolar PO2 (PACO2) with concomitant lack of CO2 delivery (apnoea, i.e. the CO2 concentration remains constant) lead to a continuing sufficient oxygenation of blood during its passage through the lung capillaries, then this leads to a rightwards shift of the CO2 binding curve--the Haldane effect. The resulting increase in PCO2 as shown here actually leads to an arterial-mixed venous CO2 partial pressure difference (avDPCO2) of 2.8 +/- 1.8 mmHg. The results described substantiate for the first time the existence of the Haldane effect under clinical conditions.

Ferrocyanide as electron donor to cytochrome aa3. Cytochrome c requirement for oxygen uptake

1. In the absence of cytochrome c, ferrocyanide or ferrous sulphate reduces cytochrome c oxidase (EC 1.9.3.1), but no continuous oxygen uptake ensues, as it does with N, N, N′, N′-Tetramethyl- p-phenylenediamine or reduced phenazine methosulphate as reductants, unless a substoichiometric amount of cytochrome c or an excess of clupein is present. Cytochrome c cannot be replaced by porphyrin cytochrome c. 2. Cytochrome c, porphyrin cytochrome c and clupein all stimulate the reduction of cytochrome aa 3 by ferrocyanide. 3. A model is proposed to explain these findings in which a high-affinity site for cytochrome c on the oxidase regulates the access of hydrophilic electron donors to a low-affinity site, and reduction via the high-affinity site is required for continuous oxygen uptake. 4. Furthermore, it is shown that upon reaction of oxidase with ferrocyanide, cyano-oxidase is formed.

Development of a continuous respirometer

A continuous oxygen uptake meter or continuous respirometer was developed which produced a rapid and reliable response to systemic shocks. The respirometer basically is a 101. Plexiglas laboratory activated sludge unit with a variable volume air tight side car. The feed enters the completely mixed aeration basin and is pumped into the side car. The side car is the site of the oxygen uptake measurements as indicated by a continuously monitoring dissolved oxygen probe. The system was most sensitive to changes in influent concentrations when run at an F/ M = 0.1. Response time for a change in DO of 0.1 ppm was less than 4 min. The continuous respirometer was tested employing both synthetic and raw industrial wastes.

Optically active co-ordination compounds. Part XVII. Oxygenation of cobalt(II)–dipeptide complexes

The uptake of oxygen by alkaline solutions of cobalt(II) with 19 dipeptides has been studied manometrically. The observed uptakes indicate three classes of behaviour: (i) stoicheiometry 102:4Co:8 dipeptides (e.g. with gly-L-tyr), (ii) stoicheiometry 102:2Co:4 dipeptides (e.g. with gly-gly), and (iii) continuous oxygen uptake with catalytic oxygenation of the dipeptide (e.g.gly-L-trp). Evidence for the products required by such stoicheiometries is given. The complexes present in the system are characterised and structural suggestions are made.