The effect of bupivacaine on gastrocnemius muscle contractility in rats with diabetes

This study examined the changes in skeletal muscle contraction parameters after the injection of bupivacaine into the gastrocnemius muscle in diabetic rats. Forty male Wistar albino rats (230-270 g) were divided into four groups: Group I: Untreated healthy control; Group II: Healthy injected with Bupivacaine; Group III: Diabetic control; Group IV: Diabetic injected with bupivacaine. The diabetes was induced with streptozotocin in 0.1 M citrate buffer (pH 4.5) injection at 45 mg/kg in tail vein. On 7th day of streptozotocin injection, the rats in groups II and IV were injected with 0.25% bupivacaine at 8 mg/kg body weight into the gastrocnemius muscle. Three weeks post bupivacaine application, the animals were sacrificed and right leg gastrocnemius muscle was isolated for studying various parameters such as muscle twitch, tetanic force, contraction and relaxation time and maximum contraction and relaxation rates. The blood glucose estimation showed that the rats in group III and IV developed diabetes at two days after administration of streptozotocin. The administration of bupivacaine resulted in a significant (p<0.05) increase in the muscle twitch parameters both in Group II and Group IV. Thus, bupivacaine can increase muscle contractility in diabetic muscles also.