[The chondrotoxic and apoptotic effects of levobupivacaine and bupivacaine on the rabbit knee joint]

Abstract

Background: A single dose injection or continuous infusion of local anesthetics into the joint space is considered to be a well-defined analgesia technique. The aim of this study was to investigate the chondrotoxic and apoptotic effects of single-dose intra-articular injection of levobupivacaine and bupivacaine on rabbit knee joint tissues.

Materials and methods: The animals were allocated into two groups each containing 20 rabbits. 0.5% levobupivacaine (Group L) and 0.5% bupivacaine (Group B) were applied intra-articularly to the left posterior joints of rabbits. At the same time, normal saline was applied to the right posterior leg knee joints of rabbits in both groups and used as a control (Group S). At the end of the 7th and 28th days after the intraarticular injections, ten randomly chosen rabbits in each group were killed by applying intraperitoneal thiopental. Sections of cartilage tissue samples were stained for light microscopic examinations and the TUNEL method was used to investigate apoptotic cells.

Results: As a result of immunofluorescence microscopic examination, the number of apoptotic cells in Group B at day 7 and day 28 were both significantly higher than Group L and S (p < 0.05). Also, the number of apoptotic cells in Group L at day 7 and day 28 were both significantly higher than Group S (p < 0.05).

Conclusions: We found that bupivacaine is more chondrotoxic than other anesthetic agent and increases the number of apoptotic cells. These results indicated that bupivacaine caused high chondrotoxic damage and it led to more apoptotic activation than levobupivacaine.

Keywords: Anestésico local; Apoptose; Apoptosis; Bupivacaine; Bupivacaína; Chondrotoxicity; Condrotoxicidade; Levobupivacaine; Levobupivacaína; Local anesthetic.

Figure 1

Light microscopic view of cartilage tissue samples taken 7 days (A) and 28 days (B) after 0.9% normal saline injection. Light microscopic view of cartilage tissue samples taken 7 days (C) and 28 days (D) after 0.5% bupivacaine injection. Light microscopic view of cartilage tissue samples taken 7 days (E) and 28 days (F) after 0.5% levobupivacaine injection (H&E, ×200). Arrow: Chondrocytes, Thick arrow: Interterritorial matrix.

Figure 2

Immunofluoresence microscopic views of cartilage tissue samples taken 7 days (A) and 28 days (B) after 0.9% normal saline injection. Immunofluoresence microscopic view of cartilage tissue samples taken 7 days (C) and 28 days (D) after 0.5% bupivacaine injection. Immunofluoresence microscopic view of cartilage tissue samples taken 7 days (E) and 28 days (F) after 0.5% levobupivacaine injection (TUNEL × 40, bar = 100 μm). Arrow, Chondrocytes; Thick arrow, Interterritorial matrix; Star, Apoptotic cells.

Figure 3

Graphic of changes in the apoptotic cell numbers according to fluorescence microscopic examination.