AJP - Endocrinology and Metabolism, Vol 240, Issue 3 333-E339, Copyright © 1981 by American Physiological Society
Changing activities of galactose-metabolizing enzymes during perfusion of suckling-rat liver
S. Rogers and S. Segal
The specific activities of the galactose-metabolizing enzymes,
galactokinase (EC 2.7.1.6), galactose-1-phosphate uridyltransferase (EC
2.7.7.12), and UDPgalactose 4-epimerase (EC 5.1.3.2), in suckling-rat
livers perfused for 90 min with 1 and 4 mM galactose fluctuate
significantly with a different pattern of change for each enzyme. Perfusion
for 30 min with galactose resulted in a significant increase of transferase
specific activity followed by a precipitous decline to about one-fifth of
the activity in unperfused liver at 90 min. The increase in transferase
activity was also observed when D-glucose was perfused but not when
L-glucose, D-fructose, D-xylose, or D-ribose was added to the perfusate. No
such changes in transferase activity were observed when adult-rat liver was
perfused with galactose. Epimerase activity in the suckling-rat liver was
relatively low, and the changes in its activity correlated best with the
uptake rate of galactose. The perfused suckling-rat liver may provide a
model system for examination of factors that modulate the specific activity
of galactose-metabolizing enzymes and effect the metabolism of galactose.
