DNA polymerases and Ki-67 nuclear antigen are induced in correlation with the resected mass of rat liver up to 90%.
OBJECTIVE
We studied the regeneration potential by measuring induction of DNA polymerases in the remnant rat liver after a partial hepatectomy (PHx) that is maximal but compatible with survival.


METHODS
The regenerating rat liver was obtained after the 90% PHx. The induction of activities of DNA polymerase alpha, delta, and epsilon were measured after partial purification. The Ki-67 nuclear antigen was also detected histochemically. These parameters were compared with those after both 30% and 70% PHx.


RESULTS
The 90% hepatectomy resulted in the strong inductions of DNA polymerase alpha, delta, and epsilon, at 48 h after operation, in association with increases in wet weight and total DNA in the remnant liver. The enzyme induction was much higher after 90% PHx than after 30% and 70% hepatectomy, in correlation with the resection volume. At 48 h after 90% hepatectomy, the Ki-67 positive cells increased up to 47.2% of hepatocytes in the remnant liver.


CONCLUSIONS
The higher induction of replication enzymes by 90% hepatectomy reflects more cells entering mitogenic cell cycle, which supports the fast regeneration of the remnant liver. The number of proliferating hepatocytes is stringently controlled by an unknown mechanism sensing the mass of resected liver parenchyma.
Sakaguchi
K
K
First Department of Surgery, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Japan.
Takeuchi
E
E
Suzuki
M
M
Oda
K
K
Nagino
M
M
Nimura
Y
Y
Yoshida
S
S
D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001663:Bilirubin / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D004256:DNA Polymerase I / Q000096:biosynthesis; D004257:DNA Polymerase II / Q000096:biosynthesis; D004258:DNA Polymerase III / Q000096:biosynthesis; D004259:DNA-Directed DNA Polymerase / Q000096:biosynthesis*; D004790:Enzyme Induction; D006498:Hepatectomy; D019394:Ki-67 Antigen / Q000096:biosynthesis*; D008099:Liver / Q000201:enzymology / Q000276:immunology / Q000601:surgery*; D008115:Liver Regeneration; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D019394:Ki-67 Antigen; D001219:Aspartate Aminotransferases; D004256:DNA Polymerase I; D004257:DNA Polymerase II; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D001663:Bilirubin