Capillary Density in the Isolated Perfused Guinea Pig Heart During Normoxic and High-Flow Hypoxic Perfusion
It has been shown that by taking NADH fluorescene photographs of isolated hypoxically perfused rat hearts, the pattern of anoxic zones can be visualised1. In high-flow-hypoxia (HFH) experiments, where arterial oxygen tension was reduced below an arterial PO2 of 400 mm Hg, while coronary flow increased, anoxic zones appeared with several hundred microns in extension, an order of magnitude far greater than intercapillary distances2. In fotometric experiments measuring simultaneously myoglobin O2 saturation and cytochrome aa3 redox state, it could be shown by us that with an arterial PO2 of 400 mm Hg about 30% of the tissue was anoxic3. Similar experiments performed by B. Chance, who used the cytochrome c redox potential, indicated a linear relation between reduced cytochromes and desaturated myoglobin during impaired oxygen supply. Inspite of the different O2 affinities of these intrinsic oxygen sensors, steep oxygen gradients within myocardial tissue were proved 4–6.
KeywordsIschemia Chrome Hexa Hexagonal Shrinkage
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