Abstract
1. Rat and guinea pig lungs were shown to possess uridinediphosphate glucuronyltransferase activity which occurs in the microsomal fraction of lung homogenates. The O-glucuronides formed were identified by using radioactive isotopes and chromatographic techniques, and by hydrolysis by β-glucuronidase.
2. UDP-glucuronyltransferase activity in the lung was 1/3–2/3 of that in the liver when calc. per mg microsomal protein, but less than 10% per unit wet weight. The activity of guinea pig lung was twice that of rat lung.
3. Digitonin enhanced the activity of the UDP-glucuronyltransferase of the lung 2–3-fold, compared with 4–5-fold in the liver of the guinea pig and 8–9-fold in liver of the rat. Digitonin increased the apparent Km value for 4-methyl-umbelliferone 5-fold both in the pulmonary and hepatic microsomes.