The effect of lipid concentration on myosin heavy chain isoform expression in cultured Weddell seal skeletal muscle cells (1102.26)

Prior studies have shown that myoglobin expression is increased when muscle cells are exposed to hypoxia and a second stimulus such as exercise. Aerobic muscle fibers expressing either Type I or IIA myosin heavy chains (MHC) have more myoglobin than other fiber types, and changes in the expression of myoglobin are usually attributed to a change in fiber type. Recently, De Miranda et al. (2012) showed that cultured Weddell seal skeletal muscle cells grown in normoxic conditions experienced an increase in myoglobin expression in response to increased lipid concentration in the culture media. The objective of this study was to determine if increasing lipid in the media would affect the expression of MHC that would underlie the increase in myoglobin expression. Weddell seal cells from primary culture were proliferated in normoxic conditions for seven days in growth media supplemented with either 2.5% or 5.0% lipid, and both treatments were differentiated for seven days in either hypoxic (0.5% oxygen) or normoxic (21% oxygen) environments. Cells were homogenized, and protein was separated via gel electrophoresis and stained with Coomassie. A difference in the presence of MHC isoforms was not detected between the 2.5% and 5.0% treatment groups, in either oxygen condition. We conclude that lipid may be acting independent of changes in MHC via another undescribed pathway to increase myoglobin expression. Grant Funding Source : Supported by Colorado State University