Variations in the glucuronidation rate and in the composition of the endoplasmic reticulum of the wild and semi-domestic reindeer (Rangifer tarandus).

1. The activity of UDPglucuronosyltransferase was analyzed in the hepatic and renal microsomes and in the postmitochondrial supernatant fraction of the duodenal mucosa of wild and semi-domestic reindeer. 2. The total activity was about the same in the hepatic microsomes of both animal groups. When the specific activity was analyzed, the semi-domestic reindeer showed twice as high activities as the wild ones. 3. The results in the kidney and duodenum showed similar changes. 4. The protein, cholesterol and phospholipid concentrations of microsomal and postmitochondrial supernatant preparations were higher in the wild reindeer. 5. It is concluded on the basis of present results that the in vitro glucuronidation in the wild reindeer is on a lower level than in the semi-domestic ones. 6. This might be a consequence of changed membrane structure where UDPglucuronosyltransferase is located.