In vitro bone lipid synthesis in air and nitrogen

Abstract

1. 1. Several investigators have reported the effects of variable oxygen tension as related to the growth, resorption, vascularization, and fracture healing of both bone and cartilage. To date, no observations have been made on lipid synthesis as affected by oxygen partial pressure. 2. 2. To this end, new-born rat calvaria were preincubated under either nitrogen or CO 2-air (5:95, v/v) m Krebs-Ringer phosphate buffer (100 mg/100 ml glucose) Bones were then incubated four hours under identical conditions in similar media containing one of the following radioactive substrates: [ 14C]acetate, [ 14C]glucose, [ 14C]choline, [ 14C] thanolamine, [ 14C]serine (100 mg/100 ml glucose was excluded from the [ 14C] glucose experiments). 3. 3. [ 14C]Acetate-labeled cholesterol and the fatty acids of different lipid classes. Radioactivity from both [ 14C]glycerol and [ 14C] glucose was incorporated into the glycerol moiety of neutral and phosphoglycerides. [ 14C]Choline, [ 14C]ethanolamine and [ 14C] serine were found in their respective phospholipids as well as occasional unidentified components. 4. 4. The radioactivity of [ 14C]acetate-, [ 14C]ethanolamine- and [ 14C]serine-labeled lipids was generally enhanced in calvaria incubated in a nitrogen atmosphere. Some elevation was also observed with [ 14C]choline. Radioactivity of [ 14C] glucose- and [ 14C]glycerol-labeled lipids was considerably less in bones incubated in nitrogen as compared to CO 2-air (5:95, v/v).