CHANGES IN SERUM ENZYME-ACTIVITIES AFTER INJECTION OF BUPIVACAINE INTO RAT TIBIALIS ANTERIOR

This study investigated the time course of changes in serum creatine k inase (CK), aspartate aminotransferase (AST), and alanine aminotransfe rase (AST) activities after intramuscular injection of bupivacaine int o the tibialis anterior (TA) of rats. Morphological changes in muscle cells, relationships between the amount of increase in the enzyme acti vities and the muscle mass damaged, and responses of serum enzymes to additional injections of bupivacaine hydrochloride (BPVC) were also ex amined. Adult male Wistar rats (24 wk) were placed into one of four gr oups. Group A (n=7) was a control, and no injection was applied. Salin e solution (0.5 ml of 0.9%) was injected into the right TA for group B (n=5). BPVC (0.5 ml of 0.5%) was injected into the right TA for group C (n=9) and into both the right and left TA for group D (n=9). No inc reases in CK, AST, and ALT were observed for groups A and B. After BPV C injection, groups C and D showed significant (P <0.01) increases in serum enzyme activities. CK peaked 4 h after BPVC injection, and AST a nd ALT peaked 12 h postinjection, then returned to the baseline by the time infiltration of mononuclear cells into the damaged muscle cells progressed. The amount of enzyme increase was significantly larger (P <0.01) for group D compared with group C. Injection of BPVC into the r ight then into the left TA 4 h later displayed a bipolar response, and the second injection into the TA 12 wk after the first injection resu lted in smaller increase in serum enzyme activities. It appeared that increases in serum enzyme activities reflected muscle damage; however, changes in enzymes occurred in the early stage of myonecrosis.