In canine cardiac Purkinje fibers, oxygen uptake is constant at ambient oxygen concentrations ≥60% but decreases at lower concentrations, likely due to diffusion limitations.
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May inform ex vivo models of Purkinje fiber oxygenation; leaves open relevance to clinical ischemia or conduction disease.
The rate of oxygen uptake of quiescent Purkinje fibers of the dog's heart was determined using a flow respirometer and oxygen polarography. At ambient oxygen concentrations of 60% or higher the rate of uptake was 0.739 mm 3 /mg wet weight per hr at 35 C. The temperature coefficient over the range 25–35° was 2.3. The uptake was independent of the ambient oxygen concentration at oxygen concentrations equal to or greater than 60% of an atmosphere. In lower oxygen concentrations the rate of uptake was found to be depressed. The depression of uptake in the lower oxygen tensions is probably the result of diffusion limitation; it may, however, reflect dependence of resting uptake on oxygen concentration.
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Greenspan et al. (1963) studied this question.
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