Abstract
Summary
Changes in hepatic UDP-GlcNAc 2'-epimerase specific activity and concentration of CMP-NANA were measured as a function of time following injury and partial hepatectomy. Injured rats exhibited an increase in the enzyme specific activity at 24 hr which reached a maximum between 3 to 5 days at 70-75% above control levels. The specific activity then declined, returning to normal values by 10 days. Partial hepatectomy resulted in a sharp increase in the enzyme specific activity to a peak of 90% above control values at 24 hr. The specific activity then declined steadily over the next 9 days, remaining significantly elevated over the normal at 10 days.
The hepatic concentration of CMP-NANA increased rapidly, showing a 40% increase at 5 days following injury, after which it slowly declined. The values were still significantly elevated above the normal at 10 days. Partial hepatectomy, on the other hand, caused a transient decrease of about 20% below the normal at 1 day. This was followed by a rapid recovery to normal levels and beyond. CMP-NANA levels were significantly elevated above normal at 10 days.
Both actinomycin D and cycloheximide administration completely blocked the increase in the enzyme activity after injury and partial hepatectomy. The expected increase in hepatic CMP-NANA concentrations was also blocked by these inhibitors.
This research was supported by Scientific Research Fund from the Ministry of Education of Japan No. 157192.
The authors wish to thank Dr. A.M. Chandler, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, for his assistance in preparation of this manuscript. The authors also express their thanks to Dr. K. Kawamura. The Second Department of Internal Medicine, Miyazaki Medical College, for his advice.
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