Influence of protein intake on S-adenosyl methionine decarboxylase activity in normal and chronically uremic rats

The activity of S-adenosyl methionine decarboxylase (SAM decarboxylase), an enzyme mediating polyamine biosynthesis, was measured in liver and kidney of chronically uremic rats and their pair-fed controls. Effects of protein intake were assessed in groups of rats fed either 8 or 18% casein or switched from 18 to 70% casein for 14 hours. In control rats, both hepatic and renal SAM decarboxylase activities increased with the higher levels of dietary casein. In uremic rats, SAM decarboxylase activity was not responsive to alterations in protein intake. Hepatic and renal SAM decarboxylase activity was significantly higher in control rats than in uremic rats, but this was due to increases in activity that occurred with diets containing higher amounts of protein (18 and 70% casein versus 8% casein).