Enzyme levels of glucuronic acid metabolism in the liver, kidney and intestine of normal and fasted rats

Abstract

Uridine diphosphate glucose dehydrogenase activity was normally highest in the liver, followed by the intestine and kidneys. The activity was significantly lower in the liver of fasted than of fed animals. ß-Glucuronidase activity was higher in the liver and intestine of fasted than of fed rats. Glucuronidation was low in the kidney and intestine compared with the liver. Fasting resulted in a slight decrease in this process in the intestine only. Release of phosphate from uridine diphosphate glucuronic acid during incubation was normally highest in the intestine, fasting having no detectable effect. The presence of ethylene diamine tetra-acetic acid in the assay mixture resulted in a marked increase in glucuronidation and a fall in the simultaneous release of phosphate, both these effects being particularly high in the gut. Uridine diphosphate glucuronyl-transferase activity and the release of phosphate in the presence of ethylene diamine tetra-acetic acid were higher in the liver of fasted than of fed rats. Addition of saccharo-1→4-lactone, an almost specific inhibitor of β-glucuronidase, was followed by an increase of glucuronidation in the liver but not in the kidney and intestinal homogenate and there was no detectable change in the release of phosphate. Activation was observable whether ethylene diamine tetra-acetic acid was present or not, but was less marked in the fasted liver. The role of uridine diphosphate glucose dehydrogenase, uridine diphosphate glucuronyltransferase, uridine diphosphate glucuronic acid pyrophosphatase and ß-glucuronidase in the metabolism of glucuronic acid and in the glucuronide production of fed and fasted animals is discussed.