Abstract
1. 1. A low UDP glucuronyltransferase (4-methylumbelliferone) activity was detected in the brain, heart, retroperitoneal fat and diaphragm of the rat. No activity could be observed in the blood. An intermediate activity resided in the thymus, spleen and lung. The highest activity per unit weight was in the liver, duodenal mucosa, adrenal gland and kidney. 2. 2. The placenta from rat, rabbit and guinea pig exhibited a microsomal UDP glucuronyltransferase activity towards 4-methylumbelliferone. The activity was highest in the placenta from guinea pig, where it was about 10% of the level in the fetal liver. 3. 3. Alveolar macrophages from rat and guinea pig had low whereas those from rabbit had no UDP glucuronyltransferase activity. The alveolar macrophages evidently are not the only cells in the lungs capable of glucuronide synthesis. 4. 4. To obtain true values for the UDP glucuronyltransferase activity in the 12,000 g supernatant fractions from the spleen, thymus and lung, it was necessary to block the action of the β-glucuronidase in the incubation with d -glucaro-1,4-lactone. 5. 5. Although the activity of the UDP glucuronyltransferase is widely distributed in the different organs and tissues, the liver, gastrointestinal mucous membrane and kidney evidently are most important quantitatively, and the liver has by far the highest capacity for glucuronidation due to its size and high activity.
Published Version
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