[Effect of ropivacaine on Ca function of skinned skeletal muscle]

It is well know that the amide-linked local anesthetics such as lidocaine accelerate Ca induced Ca release (CICR) rate. Since ropivacaine is a new amide-linked local anesthetic, effects of ropivacaine on Ca functions were studied using skinned skeletal muscle. The extensor digitorum longus muscle of male Hartley guinea pigs of about 500 g was prepared for this study. According to Endo's method, CICR rates were measured using chemically skinned fibers. Ropivacaine accelerated the (CICR) rate only at concentrations of 3 mM and 10 mM with pCa 5.0. Ropivacaine at a concentration of 10 mM inhibited initial rate of Ca uptake by sarcoplasmic reticulum. Ca sensitivity of the contractile system was not affected with 10 mM of ropivacaine. These results suggest that ropivacaine can be used safely in patients susceptible to malignant hyperthermia since ropivacaine 3 mM is not a concentration for clinical use.