Effect of Cisatracurium to Intensify Diaphragmatic Atrophy in Mechanically Ventilated Rats

  Objective   To investigate the role of cisatracurium in diaphragm atrophy in mechanically ventilated (MV) rats and its possible mechanism.

  Methods   30 adult male Sprague-Dawley (SD) rats were randomly assigned to 5 groups: Rats in the control (CON) group (n=6) were fasted for 30 h without any other intervention; rats in the MV group (n=6) were fasted for 6 h, and then mechanically ventilated for 24 h while receiving continuous infusion of sodium pentobarbital and 0.9% NaCl; rats in the MV+cisatracurium (MVC) group (n=6) were fasted for 6 h, and then mechanically ventilated for 24 h while receiving continuous infusion of sodium pentobarbital and cisatracurium; rats in the MV+chloroquine (QMV) group (n=6) and rats in the MV+cisatracurium+chloroquine (QMVC) group (n=6) received intraperitoneal injection of chloroquine (30 mg/kg), an autophagy inhibitor, at 24 h and 30 min prior to MV in addition to the treatments given to the MV group and the MVC group, respectively. The rats in each group were sacrificed 30 hours later, and costal diaphragm muscle specimens were collected. The cross-sectional area (CSA) of the diaphragm fibers was observed through HE staining, and the colocalizations of TOM20 and LC3 were assessed by immunofluorescence staining. The expression levels of PINK1, Parkin, P62 and LC3, the mitophagy-related proteins, and the expression levels of MAFbx and MURF-1, muscular-atrophy-related proteins, were evaluated by Western blot.

  Results   Respective comparisons of the MV group with the CON group and the MVC group with the MV group showed that the CSA decreased (P<0.05), the expression of MURF-1, MAFbx, PINK1, Parkin and LC3Ⅱ/Ⅰproteins increased (P<0.05), the number of co-expressed mitochondria of TOM20 and LC3 and the expression of LC3 increased and the expression of P62 protein decreased (P<0.05) in the MV and MVC groups. Respective comparisons of the QMV group with the MV group and the QMVC group with the MVC group showed that the CSA increased (P<0.05), the expression of MURF-1, MAFbx, PINK1, Parkin and LC3Ⅱ/Ⅰ proteins increased (P<0.05), the number of co-expressed mitochondria of TOM20 and LC3 and the expression of LC3 decreased and the expression of P62 protein decreased (P<0.05) in the QMV and QMVC group.

  Conclusion   Mechanical ventilation for 24 h caused diaphragm atrophy in SD rats. Cisatracurium may aggravate diaphragm atrophy in mechanically ventilated rats through the autophagy-lysosome (AL) pathway, a process that may be related to the PINK1/Parkin-mediated mitophagy, and chloroquine may reduce diaphragmatic atrophy induced by cisatracurium by blocking the AL pathway.