Meeting Abstract
Previous research has shown that skeletal muscle fibers often grow to the brink of oxygen diffusion limitation. This increase in fiber size leads to a reduction in energy consumption devoted to maintaining the membrane potential across the sarcolemma in resting muscle, since large fibers have a lower surface area to volume than small fibers. For this study we proposed that whole animal resting metabolic rate would be related to the total membrane area of the animal. We hypothesized that the standard metabolic rate in a number of fishes would be positively correlated to membrane lipid content, but unrelated to non-membrane lipid content. Metabolic rate was assessed using closed chamber respirometry, and lipid content was then assessed using thin layer chromatography. The oxygen consumption rate scaled negatively with body mass across all species. Six lipid classes were characterized: triacylglcerols (TAGs), free fatty acids (FFAs), sterol esters, cholesterol, and two classes of phospholipids, and all scaled negatively with body mass. As expected, standard metabolic rate was positively correlated with membrane lipids, and not with TAGs. These results suggest that the degree of metabolic compartmentalization has a significant impact on variation in standard metabolic rate.
