Biosynthesis of Guanidinoacetic Acid in Isolated Rat Hepatocytes

Guanidinoacetic acid (GAA), a precursor of creatine, is formed from arginine and glycine by transamidinationl. GAA formation in rat is not detected in liver homogenates2 or in isolated perfused livers3. Therefore, creatine synthesis in rat liver is regulated by the activity of transamidinase in the kidney4. However, recent improvements in GAA analysis reveal that the blood level is 1/4 of the value6 reported previously3. Moreover, Natelson et al. reported that isolated rat hepatocytes had GAA synthetic activity5. The details of which are not clear. Therefore, GAA synthesis in isolated rat hepatocytes was investigated quantitatively to evaluate the role of its synthesis in liver. In addition, some regulatory mechanisms in this synthesis were also investigated.