Abstract
Oxygen transport within the tissue occurs by diffusion and produces an oxygen pressure field. To describe its heterogeneity histograms of local P o 2 values are used. P o 2 profiles measured with small polarographic microelectrodes demonstrate that a large heterogeneity of the amplitudes of local P o 2 changes (Δ P o 2/distance) exists. Therefore, we investigated whether the amplitudes of local P o 2 changes can be used to obtain additional information about the state of oxygen supply. Six P o 2 profiles in the renal cortex of the dog were evaluated. The frequency histograms of the local P o 2 values showed a normal oxygen supply of the kidneys. To analyze the heterogeneity of the amplitudes of the local P o 2 changes every 10 μm the (Δ P o 2/distance) values were determined. Most of the amplitudes steps are in the range of ±10 torr. The frequency histogram of the amplitudes steps shows a symmetric form: 100% are between −35 and +49 torr, 90% between −12 and +11 torr. Changes of the amplitude histogram occur if the distances between the selected adjacent points are varied. At distances larger than 100 μm the amplitude histograms became disintegrated. Interestingly, the local P o 2 histograms remained practically unchanged. Therefore we conclude, that by this measuring and evaluation technique histograms of the (Δ P o 2/μm) values are obtained by which the state of oxygen supply of local structures can be monitored, probably of the microcirculatory unit of capillary oxygen supply. The results demonstrate a well-regulated oxygen pressure field within the kidney. Similar results were obtained from P o 2 profiles measured in the brain cortex (Δ P o 2/50 μm).
Published Version
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