RESUMO
Objective To investigate the different responses of diaphragm and peripheral muscles to cisatracurium in rabbits.Methods 8 male New zealand rabbits were anaesthetized with pentobarbital,and then the diaphragm,tibialis anterior,soleus muscles,phrenic nerves,tibial nerve,and peroneal nerve were gently freeded.The muscles were secured to force displacement transducers,and the nerves were directly stimulated by electrodes with supramaximal square waves.The isometric force of twitch tention of each muscle was recorded.The cumulative dose-response technique was separately used for obtaining the ED50and ED95 values of the cisatracurium in each muscle.Results The muscle-relaxing of cisatracurium on the three muscles in were observed in a dose-dependent manner.The ED50 values and ED95 values were: diaphragm(39.3 ± 2.5)μg/kg and(75.7 ± 4.2)μg/kg,tibialis anterior(80.6 ± 7.5)μg/kg and(123.3 ±9.3)μg/kg,soleus(80.0 ± 7.1)μg/kg and(126.9 ± 9.4)μg/kg,respectively.It had significant difference between diaphragm vs tibialis or soleus,P ＜ 0.05.Conclusions The muscle relaxant effects of cisatracurium on diaphragm and peripheral muscles were different,and diaphragm was more sensitive than peripheral muscles.