Effects of hypoxia on in vivo glycine-C14 incorporation into pancreatic cell proteins

Abstract

The effects of graded hypoxia on glycine-C14 incorporation into subcellular components were measured in the intact mammal. Groups of three fasted male rats were injected intraperitoneally with 5 µc of glycine-2-C14 and sacrificed at 5 (or 10), 15, 20, 30, and 45 min by decapitation. In one experimental series the environmental pO2 was maintained at 35 mm Hg for 2 hr before injection and throughout the experiment. In three other experimental series, the pO2 in the sealed chamber was maintained at 58, 48, and 38 mm Hg for 45 min before injection and for the duration of the experiment. The whole pancreases were rapidly removed, cooled, homogenized, and pooled before separation of cell fractions by ultracentrifugation. The specific activities (counts/min per µg of amino acid or protein N) were obtained for plasma and supernatant fraction ("cell sap") amino acids and for the purified proteins of zymogen granule, mitochondrial, microsomal, and cell sap fractions from micro-Kjeldahl analyses and liquid-scintillation counting. No detectable changes were found in the turnover of plasma amino acids during graded hypoxia. Amino acid incorporation into the proteins of all cell fractions was depressed stepwise with increasing degrees of hypoxia.