Abstract
Acute ischemia–reperfusion injury in skeletal muscle is a significant clinical concern in the trauma setting. The mitochondrial permeability transition inhibitor NIM-811 has previously been shown to reduce ischemic injury in the liver and kidney. The effects of this treatment on skeletal muscle are, however, not well understood. We first used an in vitro model of muscle cell ischemia in which primary human skeletal myoblasts were exposed to hypoxic conditions (1% O2 and 5% CO2) for 6 h. Cells were treated with NIM-811 (0–20 µM). MTS assay was used to quantify cell survival and LDH assay to quantify cytotoxicity 2 h after treatment. Results indicate that NIM-811 treatment of ischemic myotubes significantly increased cell survival and decreased LDH in a dose-dependent manner. We then examined NIM-811 effects in vivo using orthodontic rubber bands (ORBs) for 90 min of single hindlimb ischemia. Mice received vehicle or NIM-811 (10 mg/kg BW) 10 min before reperfusion and 3 h later. Ischemia and reperfusion were monitored using laser speckle imaging. In vivo data demonstrate that mice treated with NIM-811 showed increased gait speed and improved Tarlov scores compared to vehicle-treated mice. The ischemic limbs of female mice treated with NIM-811 showed significantly lower levels of MCP-1, IL-23, IL-6, and IL-1α compared to limbs of vehicle-treated mice. Similarly, male mice treated with NIM-811 showed significantly lower levels of MCP-1 and IL-1a. These findings are clinically relevant as MCP-1, IL-23, IL-6, and IL-1α are all pro-inflammatory factors that are thought to contribute directly to tissue damage after ischemic injury. Results from the in vitro and in vivo experiments suggest that NIM-811 and possibly other mitochondrial permeability transition inhibitors may be effective for improving skeletal muscle salvage and survival after ischemia–reperfusion injury.
Highlights
Acute limb ischemia–reperfusion (I/R) injury is a significant clinical concern that can lead to local cell death and inflammation in skeletal m uscle[1,2,3] and to systemic changes referred to as the systemic inflammatory response[4,5]
The lactate dehydrogenase assay (LDH) data indicate that 5 μM NIM-811 was significantly more effective in ameliorating ischemic injury compared to higher doses (10–20 μM) of NIM-811 (Fig. 1B)
Skeletal muscle is highly susceptible to ischemic insult, and ischemia may cause irreversible muscle damage depending on the duration of impaired p erfusion[25]
Summary
Acute limb ischemia–reperfusion (I/R) injury is a significant clinical concern that can lead to local cell death and inflammation in skeletal m uscle[1,2,3] and to systemic changes referred to as the systemic inflammatory response[4,5]. The prolonged opening of the mPTP interrupts the mitochondrial electron transport chain (membrane depolarization), disturbs mitochondrial energy production, and induces production of reactive oxygen species (ROS)[10,11]. These actions release different molecules from the dysfunctional mitochondria that can drive cell d eath[12,13]. We tested the prediction that the positive effects of NIM-811 and mPTP inhibition on cell survival would translate to muscle-specific changes in inflammation as well as improvements in gait function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
