Bimodal Effect on Pancreatic b-Cells of Secretory Products From Normal or Insulin-Resistant Human Skeletal Muscle

RESEARCH DESIGN AND METHODS—Human skeletal muscle cells were cultured for up to 24 h with tumor necrosis factor (TNF)-a to induce insulin resistance, and mRNA expression for cytokines was analyzed and compared with controls (without TNF-a). Conditioned media were collected and candidate cytokines were measured by antibody array. Human and rat primary b-cells were used to explore the impact of exposure to conditioned media for 24 h on apoptosis, proliferation, short-term insulin secretion, and key signaling protein phosphorylation and expression.