Effects of inhibitors of decarboxylase and ornithine decarboxylase on DNA synthesis in rat liver after partial hepatectomy

Deoxycytidylate deaminase activity and net synthesis of deoxyribonucleic acid (DNA) in vivo were found to increase at approximately the same time during the early stages of liver regeneration. However, deaminase activity in the regenerating liver remained at a high level for 1 day after DNA synthesis had slowed down again during the later stages of regeneration. The increase in deaminase activity was restricted as a result of exposure to 600 r X radiation during early regeneration, but this effect only became evident 11–16 hours after the irradiation. Irradiation on the second day after partial hepatectomy, when deaminase levels in control regenerating livers were relatively constant, failed to affect the deaminase activity immediately but did produce a 40–50% decrease in activity 11–16 hours later. Other antimitotic agents, e.g., colchicine, had little effect on deaminase activity.

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Inhibition of polyamine accumulation and deoxyribonucleic acid synthesis in regenerating rat liver

Biochemical Journal ◽

10.1042/bj1580485 ◽

1976 ◽

Vol 158 (2) ◽

pp. 485-488 ◽

Cited By ~ 58

Author(s):

H Pösö ◽

J Jänne

Keyword(s):

Partial Hepatectomy ◽

Ornithine Decarboxylase ◽

Rat Liver ◽

Deoxyribonucleic Acid ◽

Acid Synthesis ◽

Liver Protein ◽

Polyamine Synthesis ◽

Total Liver ◽

Regenerating Rat Liver ◽

Deoxyribonucleic Acid Synthesis

Repeated injections of 1,3-diaminopropane into rats after partial hepatectomy caused a repression-type inhibiton of liver ornithine decarboxylase (EC 4.1.1.17) and totally prevented the marked increases in liver putrescine and spermidine concentrations that normally occur in response to partial hepatectomy. The inhibition of polyamine synthesis by diaminopropane was accompanied by a profound decrease (about 80%) in the synthesis of DNA in the regenerating rat liver without any changes in the synthesis of RNA and total liver protein.

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Cholesterol metabolism in regenerating liver of the rat

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1985.249.6.g679 ◽

1985 ◽

Vol 249 (6) ◽

pp. G679-G684 ◽

Cited By ~ 1

Author(s):

F. J. Field ◽

S. N. Mathur ◽

D. R. LaBrecque

Keyword(s):

Dna Synthesis ◽

Partial Hepatectomy ◽

Rat Liver ◽

Cholesterol Synthesis ◽

Cholesterol Metabolism ◽

Reductase Activity ◽

Plasma Cholesterol ◽

Regenerating Liver ◽

Acyltransferase Activity ◽

Regenerating Rat Liver

The regenerating rat liver was used as a model to investigate the necessity for new cholesterol synthesis prior to the onset of cell division. Plasma cholesterol levels in partially hepatectomized rats were significantly decreased 24 and 48 h after surgery compared with levels in sham-operated animals. Hepatic cholesteryl ester content was also significantly increased in livers from partially hepatectomized animals, but the hepatic content of unesterified cholesterol was not affected. Hepatic triglyceride content was significantly increased within 6 h after surgery in the regenerating liver. The triglyceride levels reached a peak at 24 h, and by 72 h they had decreased back to levels that were no different from control. In the regenerating liver, microsomal 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase activity was increased 12 h after surgery. The activity of this enzyme remained significantly elevated throughout the 72-h period after surgery. In contrast, 12 h after partial hepatectomy the rate of hepatic cholesterol synthesis was significantly lower than that observed in livers from sham-operated rats. An increase in the rate of cholesterol synthesis was not observed until 48 h after partial hepatectomy, some 32 h after the start of DNA synthesis. Microsomal acyl-CoA:cholesterol acyltransferase activity was unchanged except for a 28% decrease at 72 h after partial hepatectomy. The data suggest that new cholesterol synthesis is not a requirement prior to the initiation of DNA synthesis in the regenerating rat liver.(ABSTRACT TRUNCATED AT 250 WORDS)

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