Lidocaine modifies the effect of succinylcholine on muscle oxygen consumption in dogs

The effects of succinylcholine (SCh: 2 mg/kg) alone and in combination with lidocaine (4.5 mg/kg in two increments) on muscle oxygen consumption (VO2) and blood flow (MBF) in normal and denervated gastrocnemius muscle were studied in 18 dogs anesthetized with halothane (0.94%, end tidal) to examine the interactions of both drugs at the neuromuscular junction. In an additional five dogs with normal gastrocnemius muscle, the effects of lidocaine alone on VO2 and MBF were also studied. In normal muscle, VO2 increased as much as 150% with SCh alone, while with the combination of lidocaine and SCh, VO2 remained unchanged. MBF remained unchanged with SCh alone and the combined use of lidocaine and SCh. Neither the VO2 nor MBF was affected by lidocaine alone. In denervated muscle, VO2 increased as much as 304% with SCh alone and MBF increased 115%. With the combined use of SCh and lidocaine the VO2 in denervated muscle increased up to 360% with a 290% increase in MBF. These findings indicate different effects of lidocaine on metabolic and circulatory responses to SCh in normal and in denervated muscles in dogs.