scholarly journals A comparison of isometallothionein synthesis in rat liver after partial hepatectomy and parenteral zinc injection

1984 ◽  
Vol 217 (1) ◽  
pp. 85-92 ◽  
Author(s):  
K Cain ◽  
B L Griffiths
Keyword(s):  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Half Life ◽  
Intraperitoneal Injection ◽  
Time Course ◽  
Regenerating Liver ◽  
Unequal Distribution ◽  
Post Operation ◽  
Zinc Levels

The time course of hepatic zinc-isometallothionein synthesis was studied in the regenerating liver and compared with that produced after the parenteral injection of zinc (6 mg of Zn2+/kg). In the regenerating liver, zinc levels rose rapidly after partial hepatectomy and reached a maximum at approx. 14h before declining to approximately normal levels at 48h post-operation. During this 48h period most of the zinc was incorporated into metallothionein. Purification of the latter into the charge-separable isometallothioneins (i.e. MT1 and MT2) showed that, in the regenerating liver, there was an unequal distribution of zinc between the two isoproteins. Thus at operation the endogenous thionein had an MT2/MT1 ratio of 1; after regeneration this ratio increased, and all times during the time course there was more MT2 than MT1. In contrast, the intraperitoneal injection of zinc produced a biphasic uptake of zinc into the liver with maxima at 10h and 32h. During the first phase of zinc uptake, metallothionein synthesis increased rapidly and, unlike the regenerating liver, the MT2/MT1 ratio of 1 remained constant. Thereafter, this ratio increased in a manner analogous to that exhibited by the regenerating liver. Half-life determinations for thionein disappearance/degradation shows that MT2 and MT1 were degraded with half-lives (t1/2) of 26.18h and 16.44h respectively in the regenerating liver and 14.75h and 9.3h after zinc injection. Thus thionein disappearance/degradation in the regenerating liver was slower than that seen after zinc injection. However, in both situations MT2 was always removed at a slower rate than MT1. Calculation of the rates of thionein synthesis (assuming the above disappearance rates were constant throughout the time course) showed that, in the regenerating liver, the rate of MT2 synthesis was approximately twice that of MT1. This was not the case after zinc injection, where both isometallothioneins were synthesized in equal amounts. These results demonstrate that the rates of synthesis of MT2 and MT1 can be altered according to the metabolic status of the cell and suggest a specific role for MT2 during liver regeneration.

DEOXYCYTIDYLATE DEAMINASE LEVELS IN REGENERATING RAT LIVER

1961 ◽  
Vol 39 (6) ◽  
pp. 1043-1054 ◽  
Author(s):  
D. K. Myers ◽  
C. Anne Hemphill ◽  
Constance M. Townsend
Keyword(s):  
Dna Synthesis ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Deoxyribonucleic Acid ◽  
Regenerating Liver ◽  
Regenerating Rat Liver ◽  
High Level ◽  
Early Regeneration

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.

scholarly journals Loss and reappearance of gap junctions in regenerating liver.

1978 ◽  
Vol 78 (2) ◽  
pp. 554-564 ◽  
Author(s):  
A G Yee ◽  
J P Revel
Keyword(s):  
Gap Junctions ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Close Association ◽  
Freeze Fracture ◽  
Regenerating Liver ◽  
Bile Canaliculi ◽  
Zonulae Occludentes ◽  
Fracture Study

Changes in intercellular junctional morphology associated with rat liver regeneration were examined in a freeze-fracture study. After a two-thirds partial hepatectomy, both gap junctions and zonulae occludentes were drastically altered. Between 0 and 20 h after partial hepatectomy, the junctions appeared virtually unchanged. 28 h after partial hepatectomy, however, the large gap junctions usually located close to the bile canaliculi and the small gap junctions enmeshed within the strands of the zonulae occudentes completely disappeared. Although the zonulae occludentes bordering the bile canaliculi apparently remained intact, numerous strands could now be found oriented perpendicular to the canaliculi. In some instances, the membrane outside the canaliculi was extensively filled with isolated junctional strands, often forming very complex configurations. About 40 h after partial hepatectomy, very many small gap junctions reappeared in close association with the zonulae occludentes. Subsequently, gap junctions increased in size and decreased in number until about 48 h after partial hepatectomy when gap junctions were indistinguishable in size and number from those of control animals. The zonulae occludentes were again predominantly located around the canalicular margins. These studies provide further evidence for the growth of gap junctions by the accretion of particles and of small gap junctions to form large maculae.

Turnover of ribosomal 28S and 18S rRNA during rat liver regeneration

1983 ◽  
Vol 3 (8) ◽  
pp. 781-788 ◽  
Author(s):  
Emil N. Nikolov ◽  
Mariane D. Dabeva
Keyword(s):  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
18S Rrna ◽  
Regenerating Liver ◽  
Experimental Procedure ◽  
Rat Liver Regeneration ◽  
Synthesis And Degradation

The turnover of 28S and 18S rRNA was studied in the course of 12 d after partial hepatectomy, including the proliferative (1st to 5th d) and post-proliferative (6th to 12th d) phases of liver regeneration. Turnover data, as the day-to-day rates of synthesis and degradation of 28S and 18S rRNA, were obtained by employing a suitable experimental procedure for the estimation of the increase of the amount of rRNA in the regenerating liver. It was found that 28S and 18S rRNA are accumulated into the cytoplasm and degraded at identical rates both in the proliferative and post proliferative phases. The turnover of both rRNA moieties is markedly slower during the first 3 d of liver regeneration.

RIBONUCLEASE ACTIVITY IN REGENERATING RAT LIVER

1967 ◽  
Vol 45 (7) ◽  
pp. 1021-1026 ◽  
Author(s):  
D. J. S. Arora ◽  
G. de Lamirande
Keyword(s):  
Enzymatic Activity ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Ribonuclease Activity ◽  
Regenerating Liver ◽  
Early Stages ◽  
Regenerating Rat Liver ◽  
Ribonucleoprotein Particles

Ribonucleoprotein particles were isolated from sham-hepatectomized and partially hepatectomized animals. The levels of ribonucleic acid and of proteins, as well as the ribosomal ribonuclease activity, have been studied in regenerating liver at periods of 4, 8, 16, 36, and 72 hours after partial hepatectomy. The results showed that the amount of ribosomes in regenerating rat liver was not affected as compared with the level observed in sham-operated rats. However, a decrease of ribonuclease activity was noticed in the early stages of liver regeneration. The ribonuclease activity was practically negligible at 16 and 36 hours. Less than 50% of the enzymatic activity was regained at the 72-hour period after partial hepatectomy.Results show that the ribosomes from regenerating liver are more stable and the stabilizing factor seems to be the absence of ribonuclease.

Effects of methotrexate on rat liver regeneration after partial hepatectomy

1992 ◽  
Vol 82 (2) ◽  
pp. 181-184 ◽  
Author(s):  
Ikuyo Tsukamoto ◽  
Shosuke Kojo
Keyword(s):  
Liver Regeneration ◽  
Thymidine Kinase ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Dihydrofolate Reductase ◽  
Thymidylate Synthase ◽  
Liver Weight ◽  
Regenerating Liver ◽  
Dna And Rna ◽  
Immunoblotting Assay

1. Methotrexate was administered immediately after partial (70%) hepatectomy, resulting in complete inhibition of dihydrofolate reductase in 24 h-regenerating liver. 2. At 48 h and 72 h after partial hepatectomy, thymidylate synthase activity was increased, whereas thymidine kinase was inhibited, by the injection of methotrexate. The DNA and RNA contents and the liver weight were also reduced in methotrexate-treated rats. 3. The immunoblotting assay showed that methotrexate stimulated the synthesis of thymidylate synthase protein in 48 h-regenerating liver. At the same time, thymidylate synthase activity was directly inhibited by methotrexate. The mechanisms of inhibition of these enzymes by methotrexate appeared to be different.

Enhanced production of dolichol, but not dolichyl phosphate, in the earliest stages of rat liver regeneration

1986 ◽  
Vol 6 (4) ◽  
pp. 409-413 ◽  
Author(s):  
M. Marino ◽  
G. Bruscalupi ◽  
S. Spagnuolo ◽  
S. Leoni ◽  
M. T. Mangiantini ◽  
...  
Keyword(s):  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Physiological Significance ◽  
Regenerating Liver ◽  
Rat Liver Regeneration ◽  
Enhanced Production ◽  
Dolichyl Phosphate

The regenerating liver presents a changed ability to use mevalonate 16 hr after partial hepatectomy. The dolichol content and its synthesis from mevalonate is increased, while no variation of dolichyl-P and ubiquinone parameters are detectable. The greater amount ofmevalonate utilized to form dolichol, but not dolichyl-P, in this proliferating system, raises some questions about the physiological significance of these isoprenoid compounds and about their biosynthetic sequence.

Effect of alpha2b interferon administration on rat liver regeneration process after partial hepatectomy

1995 ◽  
Vol 108 (4) ◽  
pp. A1186
Author(s):  
S. Theocharis ◽  
A. Margeli ◽  
N. Goutas ◽  
S. Skaltsas ◽  
A. Skopelitou ◽  
...  
Keyword(s):  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Regeneration Process ◽  
Rat Liver Regeneration

Effect of thyroparathyroidectomy on the activities of thymidylate synthetase and thymidine kinase during liver regeneration after partial hepatectomy

1987 ◽  
Vol 72 (4) ◽  
pp. 455-461 ◽  
Author(s):  
Rieko Nakata ◽  
Ikuyo Tsukamoto ◽  
Masamitsu Miyoshi ◽  
Shosuke Kojo
Keyword(s):  
Dna Synthesis ◽  
Liver Regeneration ◽  
Time Dependence ◽  
Thymidine Kinase ◽  
Partial Hepatectomy ◽  
Dna Content ◽  
Thymidylate Synthetase ◽  
High Dose ◽  
Regenerating Liver ◽  
Relative Contribution

1. Thyroparathyroidectomy (TPTX) carried out at 72 h before partial hepatectomy (PH) reduced the induction of hepatic thymidylate synthetase (TS) and thymidine kinase (TK), which are rate-determining enzymes in DNA synthesis, at 24 h after PH. 2. When TPTX was carried out at 24 h before PH, TK activity at 24 h after PH was not reduced at all, yet TS activity was reduced significantly. Thus the effect of TPTX differed in time dependence between TS and TK. 3. The depression of TK activity in rats which were subjected to TPTX at 72 h before PH, was recovered by Ca2+ supplementation. This result demonstrated that the rise of TK activity in regenerating liver is regulated by plasma Ca2+. 4. Since a high dose of tri-iodothyronine (T3) was required to cause elevation of the activities of these enzymes and DNA content in 24 h-regenerating liver of TPTX rats, the relative contribution of T3 to liver regeneration may be small.

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