Muscle wasting and the temporal gene expresion pattern in a novel rat ICU model

Acute quadriplegic myopathy (AQM) or critical illness myopathy (CIM) is frequently observed in intensive care unit (ICU) patients. In order to elucidate duration-dependent effects of the ICU intervention on molecular and functional networks that control the muscle wasting and weakness in AQM, gene expression profile was analyzed at time points varying from 6 hours to 14 days in a unique experimental rat model mimicking ICU conditions, i.e., post-synaptically paralyzed, mechanically ventilated and extensively monitored animals. A total of five sham operated controls and 23 experimental female Sprague-Dawley rats were included in this study. The experimental rats were anaesthetized, treated with the neuromuscular blocker (NMBA), α-cobrotoxin, mechanically ventilated and monitored for durations varying from 6h to 4 days (n=13), from 5 to 9 days (n=4), and from 9 to 14 days (n=6). Muscle biopsies were obtained from gastrocnemius muscle (proximal part) immediately after euthanasia and were quickly frozen in liquid propane cooled by liquid nitrogen, and stored at -80°C.RNA was extracted.