Abstract
Summary
Changes in hepatic hexosamine metabolism and serum seromucoid concentrations during postnatal development were investigated in the rat. A relatively low activity of hepatic L-glutamine: D-fructose-6-phosphate aminotransferase (AT) was observed within 24 hr of birth. This rapidly increased to a maximum at about 2 weeks of age, followed by a decline to adult levels after another 2 weeks. The developmental pattern of hepatic UDP-N-acetylglucosamine 2′-epimerase (EP) closely resembled that of AT. It was relatively low in the newborn, increased to a maximum at about 2 weeks and then declined to adult values after another 2 weeks. The serum seromucoid concentration was low in new born rats and then increased gradually with development to adult levels at about 50 days.
The hepatic concentrations of UDP-GlcNAc and CMP-NANA both were relatively high at 24 hr after birth compared to values observed at 50 days. The developmental pattern observed for both over this time period was quite similar and was almost the reciprocal to that for the seromucoid fraction. After 50 days the concentration of UDP-GlcNAc remained constant at adult levels as did that of the seromucoid fraction, but the concentration of CMP-NANA showed a marked increase.
It is suggested that the hepatic concentrations of these amino-sugar nucleotides during development primarily reflect the demand for the hepatic synthesis and secretion of plasma glycoproteins as reflected in the seromucoid fraction.
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. Kazunori Kawamura, The Second Department of Medicine, Miyazaki Medical College, for his advice.
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