Ketamine-xylazine-acepromazine compared with isoflurane for anesthesia during liver transplantation in rodents

Abstract

Orthotopic liver transplantation in mice and rats is used to study a wide range of scientific questions. Inhalant anesthesia is widely used in liver transplantation models in rodents, but drawbacks of inhalant anesthetics include issues of cost, safety, and ease of use. The goal here was to find an effective injection anesthesia protocol that would not directly influence metabolic or functional parameters after liver transplantation. We compared intraperitoneal injection of a ketamine-xylazine-acepromazine cocktail (KXA) with isoflurane during 50% liver transplantation in mice and rats. Anesthesia with KXA had rapid induction (5 +/- 3 min) and a long duration of surgical anesthesia (70 +/- 10 min). The 2 methods of anesthesia produced no significant differences in liver injury (histology, serum alanine aminotransferase and total bilirubin concentrations), inflammation (IL6, TNFalpha, myeloperoxidase activity), regeneration (incorporation of 5-bromo-2'-deoxyuridine, mitotic index, restitution of liver weight), or 7-d survival. In conclusion, a KXA regimen is a safe and effective injectable anesthetic for rodent liver transplantation and is a suitable substitute for currently used inhalant anesthesia. Injectable anesthetics offer advantages in terms of cost, personal safety, and ease of use and will be particularly beneficial to microsurgeons during their training period in liver transplantation.

Figure 1.

Histologic examination of graft 48 h after 50% liver transplantation in mice. (A) Sham control. (B) Mouse anesthetized with KXA. (C) Mouse anesthetized with isoflurane. Liver collected from the sham control showed no changes histologically. Liver grafts from mice anesthetized with either KXA or isoflurane exhibited a moderate and similar level of damage, characterized by sinusoidal congestion and minimal necrosis, and a similar regenerative response characterized by increased nuclear diameter and numerous mitotic figures (white arrows). Each panel is a representative image from among the 6 animals in each group.

Figure 2.

Serum levels of ALT and total bilirubin after mouse liver transplantation. Blood samples were collected from recipient mice anesthetized with either KXA or isoflurane (ISO) at 24 and 48 h posttransplantation of 50% liver grafts. Samples were assayed for (A) ALT and (B) total bilirubin. Baseline levels (mean ± SEM, n = 6) for ALT and total bilirubin were 28.67 ± 6.35 U/L and 0.07 ± 0.05 mg/L, respectively. Data from both anesthesia groups differed (P < 0.01 for both) from those from the sham group.

Figure 3.

Incorporation of BrdU in mouse liver grafts harvested 48 h after implantation. BrdU (50 mg/kg, IP) was injected 2 h before harvest, and BrdU incorporation detected immunohistologically. Liver sections from (A) sham group, (B) isoflurane (ISO)-anesthetized group, and (C) KXA-anesthetized animals. Each panel is a representative image from among the 6 animals in each group

Figure 4.

Measurement of liver graft regeneration in mice. (A) Quantification of BrdU incorporation. (B) Increase in graft weight. (C) Mitotic index. Data are given as mean ± SEM (n = 6) for all analyses. None of the measured parameters of liver regeneration differed significantly between the KXA- and isoflurane (ISO)-anesthetized groups.

Figure 5.

Inflammatory response after small-for-size liver transplantation in mice. Hepatic inflammation as defined by serum concentrations (mean ± SEM, n = 6) of (A) TNFα, (B) IL6, and (C) hepatic myeloperoxidase (MPO) was measured by ELISA. None of the measured parameters of inflammation differed significantly between the KXA- and isoflurane (ISO)-anesthetized groups.