Effects of Hyperoxia on Heme Biosynthesis.
Summary rept., 15 Aug 71-30 Apr 72,
SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TEX
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In vitro suspensions of chicken erythrocytes, rabbit reticulocytes, and rat bone marrow cells have been used to examine the effects of oxygen tension on heme synthesis. The data indicate that heme synthesis is maximal at 10 O2 at approximately 745 torr mm. Hg. Lesser O2 levels 0, 3, 5, and 7 greatly reduce heme synthesis, while higher levels 20 and 100 moderately reduce it. Hemoglobin i.e., globin synthesis, as measured by the incorporation of H3-leucine, is unaffected by O2 tension. Although the synthesis of aminolevulinic acid ALA from glycine and succinate is considered the rate-limiting step in heme synthesis, the effects of O2 on the incorporation of glycine-C14 and ALA-C14 into heme are similar. Since 10 O2 at 745 torr approximates mean tissue PO2 at sea level, the suppression of heme synthesis at O2 levels greater than 10 may indicate the effect of hyperoxia on heme synthesis in the intact animal. Author Modified Abstract
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