Increased muscle oxygen consumption during electrical stimulation following endotoxin administration

In this study, skeletal muscle oxygen demand was increased by electrical stimulation to determine if restricted oxygen supply to skeletal muscle in endotoxin-treated dogs was limiting oxygen consumption. Skeletal muscle blood flow was measured directly and arterio-venous differences of oxygen were determined in hindlimb muscles by obtaining blood samples simultaneously from the carotid artery and profunda femoris veins. Hindlimb muscle stimulation did not influence the systemic hemodynamic parameters monitored in either saline or endotoxin treated animals, although endotoxin treated animals demonstrated the well-characterized hemodynamic changes. During stimulation, skeletal muscle oxygen consumption was elevated due to increased oxygen extraction and blood flow in both treatment groups. No significant difference in oxygen consumption by nonstimulated muscle was observed between treatment groups. However, muscle oxygen extraction following endotoxin was greater than either pre-treatment or saline extraction values. This study demonstrates that following endotoxin administration, oxygen extraction by skeletal muscle is not maximal, and the muscle can further increase oxygen extraction with greater oxygen demand. Thus, skeletal muscle oxygen supply is not limiting the oxygen consumption following endotoxin treatment.