Effect of acute peritonitis on rocuronium-induced intraperitoneal pressure reduction and the uptake function of the sarcoplasmic reticulum

Abstract

Previous studies have reported the incomplete relaxation effect of neuromuscular blockers on skeletal muscles in acute peritonitis (AP) and other inflammatory processes; however, the underlying mechanisms responsible for this effect have not yet been satisfactorily identified. The impaired removal of cytosolic Ca²⁺ through sarcoendoplasmic Ca²⁺-ATPase (SERCA) and defects in sarcoplasmic reticulum (SR) Ca²⁺ uptake are the major contributing factors to diastolic dysfunction. Previous studies on the effects of neuromuscular blockers have primarily focused on neuromuscular transmission. Because of the reduced calcium uptake in the SR itself, even when neuromuscular transmission is fully blocked, the muscle is not able to relax effectively. In the present study, the impact of AP on rocuronium-induced intraperitoneal pressure reduction and rectus abdominal muscle relaxation, and SERCA uptake function was investigated. AP was induced via gastric perforation and changes in the intraperitoneal pressure before and after the administration of rocuronium were recorded. Muscle contractile properties, uptake and release functions and SERCA activity in the rectus abdominal muscles of AP model rats were measured. The half-relaxation time in the AP group was significantly prolonged compared with that in the control group (P<0.01). The peak rate of SR Ca²⁺ uptake for whole muscle homogenates was significantly reduced (P<0.05) in AP model rats without reduction of the rate of Ca²⁺ release evoked through AgNO₃. In conclusion, gastric perforation-induced AP attenuates the intraperitoneal pressure-reducing effect of rocuronium, and AP induces diastolic dysfunction of the rectus abdominal muscle. The SR Ca²⁺-ATPase uptake rate was also reduced by AP.

Keywords: acute peritonitis; intraperitoneal pressure; rocuronium; sarcoplasmic reticulum; uptake.

Figure 1.

Systemic cytokine levels in the three groups. ^#P<0.01 vs. control group. TNF, tumor necrosis factor; IL, interleukin. n=12.

Figure 2.

Fitted volume-pressure relationship curves in the three groups. Curves for G1 and G2 were shifted leftward significantly. *P<0.05 vs. control. n=12.

Figure 3.

Change of IAP after the administration of rocuronium. ^#P<0.01 vs. control group. IAP, intra-abdominal pressure. n=12.

Figure 4.

(A) Tetanic forces of the muscle strips in the Control group (closed circles), G1 group (closed triangles) and G2 group (closed squares). Each point represents an individual rat. The horizontal line in the middle represents the mean value of group. (B) Force-frequency relation curves in three groups. ^#P<0.01 vs. control group. All data are presented as the mean ± standard error of the mean. n=12.

Figure 5.

Calcium release and uptake from muscle homogenates. (A) Typical graph showing Ca²⁺ flux over time in SR measured with Fura-2. The maximal rates of Ca²⁺ uptake and release from the SR were calculated from this graph. (B) Peak rates of SR Ca²⁺ uptake as well as AgNO₃ stimulated release in SR of rectus abdominis muscle. (C) Maximal amounts of SR Ca²⁺ uptake as well as AgNO₃-stimulated release. (D) Activity of SERCA. All data are expressed as the mean ± standard error of the mean. *P<0.05 vs. control. SR, sarcoplasmic reticulum; SERCA, sarcoendoplasmic Ca²⁺-ATPase. n=12.