Safety limit of the extent of hepatectomy for rats with moderately fatty liver: experimental study concerning living liver donor safety

A Simple and Easily Reproducible Model of Reversible Obstructive Jaundice in Rats

BACKGROUND/AIM

Cholangiocarcinoma and pancreatic carcinoma are major malignancies that cause obstructive jaundice (OJ). This study aimed to develop a simple and easily reproducible rat model of reversible OJ (ROJ).

MATERIALS AND METHODS

OJ was induced by clamping the common bile duct (CBD) using a U-shaped titanium hemoclip and its base was attached by ligation using 2-cm long 4-0 polypropylene suture. An anti-adhesive sheet was placed around the CBD. OJ was mitigated by pulling the suture to remove the clip under laparotomy 3 days later. Serum chemistry and liver histopathology were compared between the ROJ group and sham surgery (SH) groups.

RESULTS

Three days after inducing OJ, serum total bilirubin, aspartate aminotransferase, and alanine aminotransferase were remarkably elevated in the ROJ group and thereafter reduced significantly after mitigating OJ. Similar findings were confirmed by histopathology.

CONCLUSION

Our rat model of reversible OJ was considered simple and easily reproducible.

Effect of Portal Vein Ligation Plus Venous Congestion on Liver Regeneration in Rats

INTRODUCTION AND AIM

We developed a rat model of portal vein ligation (PVL) with venous congestion (PVL+C) to investigate beneficial effect PVL plus congestion for regeneration of intact liver segments.

MATERIALS AND METHODS

In the PVL group, portal vein branches were ligated except the caudate lobe (CL). In the PVL + C group, the left lateral hepatic vein was ligated in addition to PVL. Chronological changes in the following variables were compared among the groups: CL weight to body weight ratio (CL/BW), embolized liver weight to body weight ratio (EL/BW), histological findings of the embolized/non-embolized liver, and expression of several mediators that affect liver regeneration in the non-embolized liver.

RESULTS

Weight regeneration of CL continued up to postoperative day (POD)7 in PVL + C, but terminated at POD2 in PVL. CL/BW at POD7 was significantly higher in PVL + C than in PVL (2.41 ± 0.33% vs. 1.22 ± 0.18%, P < 0.01). In contrast, EL/BW continued to decrease up to POD7 in PVL + C but reached nadir at POD2 in PVL. Furthermore, EL/BW at POD7 was significantly smaller in PVL + C than in PVL (0.35 ± 0.03% vs. 0.67 ± 0.08%, P < 0.01). Histologically-proven injury in the embolized liver was more severe in PVL + C than in PVL. Expression of Ki-67, IL-6, TNF -a, and HGF were greater and/or more prolonged in PVL + C than in PVL.

CONCLUSIONS

Our rat model of PVL + C was considered useful for investigating the beneficial effect of congestion in addition to PVC. PVL + C caused increased devastation of the embolized liver, and higher and more prolonged expression of factors promoting liver regeneration in the non-embolized liver than in PVL.

Role of bile in intestinal motility after massive liver resection in conscious rats

AIM

To investigate the effect of 90% partial hepatectomy (90% PHx) and the involvement of bile on ileal motility in conscious rats.

METHODS

Two strain gauge force transducers were chronically implanted in the ileum of each of 20 rats. The rats were divided into four groups, three of which underwent 90% PHx. The experiments were performed with the rats in a conscious, fasted state. After ileal motility was recorded, bile or saline was perfused into the duodenum of each rat in two of the 90% PHx groups. The effects of the perfusion on ileal motility were observed and recorded using the motility index (MI), defined as the area under the contraction cues after surgery and expressed as the ratio to the MI in the preoperational motility. The time of the first passage of stool after surgery was recorded.

RESULTS

A typical migrating motor complex (MMC) pattern was observed in normal fasted rats. Increased MMC cycle lengths and a decreased MI at 1 day and 3 days after 90% PHx were observed. The MMC after 90% PHx was characterized by an increased duration of Phase 2-like activity. The MMC cycle length, the MI, and the time of the first passage of stool after 90% PHx were improved by perfusion of bile into the duodenum through the biliary cannula but were not influenced by perfusion of saline into the duodenum through the biliary cannula.

CONCLUSION

The MMC cycle length and the MI were inhibited after 90% PHx, with the involvement of decreased bile flow into the gastrointestinal tract by liver resection.

A rat model of a repeat 70% major hepatectomy

BACKGROUND

This study investigated the effects of a repeat 70% major hepatectomy in a rat model.

MATERIALS AND METHODS

The left lateral and median lobes of the livers of 80 seven-week-old male Wistar rats were excised during primary hepatectomy, removing a total of 70% of the liver. In 40 of the rats, the regenerated right lateral lobe, comprising 70% of the remnant liver, was excised during secondary hepatectomy 7 days after the initial procedure. The survival rate, posthepatectomized regeneration ratio, and laboratory blood data were compared between the groups that had undergone initial only and repeat hepatectomies.

RESULTS

All of the rats survived for at least 7 days after each procedure. The remaining liver returned to up to about 90% of its original wet weight by 5 days in both groups. The serum glutamic-pyruvic transaminase levels peaked 12 h after hepatectomy, remained at a similar level at 36 h, and had normalized by 2 days. Serum total bilirubin levels were similar in both groups. The total cell numbers after 5 days were significantly higher in the initial hepatectomy group than in the repeat hepatectomy group.

CONCLUSIONS

We established a rat model in which an initial 70% major hepatectomy was followed by a repeat 70% major hepatectomy of the regenerated liver. The time taken to restore the integrity of the liver was longer in the rats that underwent repeat hepatectomy. We believe that this model will be useful for investigating the regenerative ability of the liver after a second major hepatectomy.